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介孔炭材料应用于电化学催化的研究进展
梁振金, 洪梓博, 解明月, 顾栋
, doi: 10.1016/S1872-5805(22)60575-4
摘要(733) HTML(399) PDF(149)
摘要:
由于介孔炭材料具有高比表面、均一可调的孔径尺寸和形貌、良好的导电性和化学稳定性等优点,已被广泛应用到催化、吸附、分离和电化学储能等领域。近年来,多组分的掺杂与复合使介孔炭材料拥有可调变的功能性,已成为材料领域研究的一个热点。本文首先介绍介孔炭材料的合成,包括软模板法、硬模板法和无模板法等。接着论述介孔炭及其复合材料在电化学催化领域的应用,主要包括杂原子掺杂介孔炭材料以及介孔炭材料与金属化合物的复合材料在电化学催化氧还原(ORR)、析氧(OER)、析氢(HER)等领域的研究进展。此外还论述了此类材料在电催化有机合成上的应用。最后对介孔炭及其复合材料在电化学催化上的发展趋势进行了展望。 由于介孔炭材料具有高比表面、均一可调的孔径尺寸和形貌、良好的导电性和化学稳定性等优点,已被广泛应用到催化、吸附、分离和电化学储能等领域。近年来,多组分的掺杂与复合使介孔炭材料拥有可调变的功能性,已成为材料领域研究的一个热点。本文首先介绍介孔炭材料的合成,包括软模板法、硬模板法和无模板法等。接着论述介孔炭及其复合材料在电化学催化领域的应用,主要包括杂原子掺杂介孔炭材料以及介孔炭材料与金属化合物的复合材料在电化学催化氧还原(ORR)、析氧(OER)、析氢(HER)等领域的研究进展。此外还论述了此类材料在电催化有机合成上的应用。最后对介孔炭及其复合材料在电化学催化上的发展趋势进行了展望。
A comprehensive review on 3D printing of sp2 carbons: Materials, properties and applications
Satendra Kumar, Manoj Goswami, Netrapal Singh, Sathish Natarajan, Surender Kumar
, doi: 10.1016/S1872-5805(22)60651-6
摘要(77) HTML(25) PDF(15)
摘要:
Three dimensional (3D) printing is a modern technology in the 4th engineering revolution that has the possibility to transform existing production methods. It offers a novel production method of layered manufacturing and layer-by-layer stacking based on the forming principle, which radically simplifies the manufacturing process and enables large-scale customizable production. However, there are still numerous issues with this new technology. Except pure graphene, sp2 carbons can be 3D printed with little difficulty because of their hydrophilicity. The hydrophobic nature of pure graphene makes it difficult to print and process in water-based media. Thanks to the advancement of capillary inks, which allow for the 3D printing of pure graphene. The current review focuses on the most recent developments in 3D printing of sp2 carbons. A concise overview of 3D printing technologies is presented, followed by a summary of 3D printed sp2 carbons and their diverse applications. Finally, perspectives and opportunities for this new field are discussed. Three dimensional (3D) printing is a modern technology in the 4th engineering revolution that has the possibility to transform existing production methods. It offers a novel production method of layered manufacturing and layer-by-layer stacking based on the forming principle, which radically simplifies the manufacturing process and enables large-scale customizable production. However, there are still numerous issues with this new technology. Except pure graphene, sp2 carbons can be 3D printed with little difficulty because of their hydrophilicity. The hydrophobic nature of pure graphene makes it difficult to print and process in water-based media. Thanks to the advancement of capillary inks, which allow for the 3D printing of pure graphene. The current review focuses on the most recent developments in 3D printing of sp2 carbons. A concise overview of 3D printing technologies is presented, followed by a summary of 3D printed sp2 carbons and their diverse applications. Finally, perspectives and opportunities for this new field are discussed.
硫掺杂炭材料在钠离子电池负极中的研究进展
谢金明, 庄容, 杜宇轩, 裴永伟, 谭德明, 徐飞
, doi: 10.1016/S1872-5805(22)60630-9
摘要(858) HTML(102) PDF(78)
摘要:
钠离子电池因资源丰富及成本低等优势,在大规模储能领域备受关注。炭材料作为钠离子电池实用化进程中的关键负极材料,具有高容量、低嵌钠平台、易调控且稳定性好等特点,引起了研究者的广泛关注。掺杂原子可改善炭材料的微观与电子结构,是提升储钠性能的有效途径。常见的杂原子包括N、S、O、P、B等,其中硫原子因其较大的半径能显著扩大层间距、增加缺陷与活性位点,被广泛用于炭负极材料的掺杂改性。本文综述了近年来硫掺杂炭材料的设计制备及在钠离子电池负极中的研究进展,分析了硫掺杂对碳结构的调控机理与改善电池性能的作用机制,最后针对目前面临的挑战和可能的解决方案进行了总结和展望,以期推动硫掺杂炭负极材料在钠离子电池中的实用化进程。 钠离子电池因资源丰富及成本低等优势,在大规模储能领域备受关注。炭材料作为钠离子电池实用化进程中的关键负极材料,具有高容量、低嵌钠平台、易调控且稳定性好等特点,引起了研究者的广泛关注。掺杂原子可改善炭材料的微观与电子结构,是提升储钠性能的有效途径。常见的杂原子包括N、S、O、P、B等,其中硫原子因其较大的半径能显著扩大层间距、增加缺陷与活性位点,被广泛用于炭负极材料的掺杂改性。本文综述了近年来硫掺杂炭材料的设计制备及在钠离子电池负极中的研究进展,分析了硫掺杂对碳结构的调控机理与改善电池性能的作用机制,最后针对目前面临的挑战和可能的解决方案进行了总结和展望,以期推动硫掺杂炭负极材料在钠离子电池中的实用化进程。
石墨炔:一种新型二维炭材料的合成、改性与应用
张婷, 王宇晶, 于灵敏, 士丽敏, 柴守宁, 何炽
, doi: 10.1016/S1872-5805(22)60653-X
摘要(68) HTML(44) PDF(9)
摘要:
石墨炔是一类由sp和sp2杂化碳原子共同组成的新型二维材料。高度共轭及碳环大小可调的分子结构赋予石墨炔特异的物理化学性能,也为其功能化改性及应用提供了便利。近十年来,关于石墨炔的理论及实验研究正在广泛开展,在多个领域取得了一系列重要进展。本文首先对石墨炔性质进行了简要介绍,总结了不同形貌石墨炔的主要合成方法,包括Glaser-Hay交叉偶联、化学气相沉积法、范德华外延生长法、爆炸法、界面限域合成法及双极电化学法等。然后,对金属、非金属原子掺杂、修饰改性及其对石墨炔性能影响的理论计算和实验研究进行了综述;并就石墨炔基材料在环境、能源、生物医学等主要领域的研究进展进行了阐述和总结。最后,探讨了石墨炔发展亟待解决的问题和面临挑战。该综述能够为开展石墨炔相关研究提供有价值的前沿信息和方法参考。 石墨炔是一类由sp和sp2杂化碳原子共同组成的新型二维材料。高度共轭及碳环大小可调的分子结构赋予石墨炔特异的物理化学性能,也为其功能化改性及应用提供了便利。近十年来,关于石墨炔的理论及实验研究正在广泛开展,在多个领域取得了一系列重要进展。本文首先对石墨炔性质进行了简要介绍,总结了不同形貌石墨炔的主要合成方法,包括Glaser-Hay交叉偶联、化学气相沉积法、范德华外延生长法、爆炸法、界面限域合成法及双极电化学法等。然后,对金属、非金属原子掺杂、修饰改性及其对石墨炔性能影响的理论计算和实验研究进行了综述;并就石墨炔基材料在环境、能源、生物医学等主要领域的研究进展进行了阐述和总结。最后,探讨了石墨炔发展亟待解决的问题和面临挑战。该综述能够为开展石墨炔相关研究提供有价值的前沿信息和方法参考。
Review of chemical recycling and reuse of carbon fiber reinforced epoxy resin composites
TIAN Zi-shang, WANG Yu-qi, HOU Xiang-lin
, doi: 10.1016/S1872-5805(22)60652-8
摘要(97) HTML(52) PDF(27)
摘要:
Carbon fiber reinforced epoxy resin composites (CFRCs) have been used in automotive and aerospace fields due to their excellent mechanical properties. The recycling of CFRCs attracts attention worldwide in recent years. Chemical recycling is a more promising method, which can selectively destroy the specific bond of resin to achieve controllable degradation. Matrix epoxy resins are degraded into monomers or oligomers, and high-value carbon fibers can be recycled. Therefore, we focus on summarizing the progress of chemical recovery method, mainly including super- and subercritical fluids, oxidation, solvolysis, alcoholysis, electrochemical recycling and so on. In addition, the insertion of reversible chemical bonds into the resin to prepare recyclable resins is beneficial for recyling and reuse of components in CFRCs. Therefore, we also briefly introduce the synthesis and depolymerization mechanism of recyclable thermosetting resins. Finally, the possible development directions of chemical recovery of CFRCs and preparation of high-performance recyclable epoxy resins are proposed. Carbon fiber reinforced epoxy resin composites (CFRCs) have been used in automotive and aerospace fields due to their excellent mechanical properties. The recycling of CFRCs attracts attention worldwide in recent years. Chemical recycling is a more promising method, which can selectively destroy the specific bond of resin to achieve controllable degradation. Matrix epoxy resins are degraded into monomers or oligomers, and high-value carbon fibers can be recycled. Therefore, we focus on summarizing the progress of chemical recovery method, mainly including super- and subercritical fluids, oxidation, solvolysis, alcoholysis, electrochemical recycling and so on. In addition, the insertion of reversible chemical bonds into the resin to prepare recyclable resins is beneficial for recyling and reuse of components in CFRCs. Therefore, we also briefly introduce the synthesis and depolymerization mechanism of recyclable thermosetting resins. Finally, the possible development directions of chemical recovery of CFRCs and preparation of high-performance recyclable epoxy resins are proposed.
Electrospun carbon nanofibers for use in capacitive desalination of water
Bethwel K Tarus, Yusufu A C Jande, Karoli N Njau
, doi: 10.1016/S1872-5805(22)60645-0
摘要(198) HTML(76) PDF(22)
摘要:
Capacitive deionization (CDI) has rapidly become a promising approach for water desalination. The technique removes salt from water through applying an electric potential between two porous electrodes to cause adsorption of charged species on the electrode surfaces. The nature of CDI favors the use of nanostructured porous carbon materials with high specific surface area and appropriate surface functional groups. Electrospun carbon nanofibers (CNFs) are quite ideal as they have high specific surface area and surface characteristics for doping/grafting with electroactive agents. Compared with powdered materials, CNF electrodes are free-standing and don’t require binders that increase resistivity. Hierarchically structured CNFs with an appropriate distribution of mesopores and micropores have better desalination performance. Compositing CNFs with faradaic materials enhances ion storage by additional pseudocapacitance besides the electric double layer capacitance. Herein, the use of electrospun CNFs as electrodes for CDI is summarized with emphasis on the major precursor materials used and structure modification, and their relations to the performance in salt electrosorption. Capacitive deionization (CDI) has rapidly become a promising approach for water desalination. The technique removes salt from water through applying an electric potential between two porous electrodes to cause adsorption of charged species on the electrode surfaces. The nature of CDI favors the use of nanostructured porous carbon materials with high specific surface area and appropriate surface functional groups. Electrospun carbon nanofibers (CNFs) are quite ideal as they have high specific surface area and surface characteristics for doping/grafting with electroactive agents. Compared with powdered materials, CNF electrodes are free-standing and don’t require binders that increase resistivity. Hierarchically structured CNFs with an appropriate distribution of mesopores and micropores have better desalination performance. Compositing CNFs with faradaic materials enhances ion storage by additional pseudocapacitance besides the electric double layer capacitance. Herein, the use of electrospun CNFs as electrodes for CDI is summarized with emphasis on the major precursor materials used and structure modification, and their relations to the performance in salt electrosorption.
研究论文
Optimizing the carbon coating to eliminate electrochemical interface polarization in a high performance silicon anode for use in a lithium-ion battery
QI Zhi-yan, DAI Li-qin, WANG Zhe-fan, XIE Li-jing, CHEN Jing-peng, CHENG Jia-yao, SONG Ge, LI Xiao-ming, SUN Guo-hua, CHEN Cheng-meng
, doi: 10.1016/S1872-5805(22)60580-8
摘要(313) HTML(164) PDF(41)
摘要:
Ordered and disordered carbons have been commonly used as coating materials for silicon (Si) anodes, however the effect of carbons with different crystallinities and pore structures on their electrochemical performance remains controversial. We used pitch and phenolic resin (PR) as the precursors of ordered and disordered carbon, respectively, to prepare carbon-coated silicon (Si@C) with strictly controlled carbon contents and surface functional groups. Their electrochemical behavior was investigated. An ordered crystalline structure is favorable for electron transport, and mesopores and macropores are conducive to the diffusion of lithium ions. Such a coating with a small pore volume is an excellent buffer for the expansion of Si, and the electrode maintains structural integrity for 50 cycles. A disordered porous structure is less robust and produces a large polarization, which produces continuous volume expansion with cycling and leads to inferior electrochemical performance. As a result, the capacity and capacity retention after 100 cycles at 0.5 A g−1 of Si@C-Pitch are respectively 8 times and 1.9 times those of Si@C-PR. This study provides theoretical guidance for the selection of carbon materials used in Si@C anodes. Ordered and disordered carbons have been commonly used as coating materials for silicon (Si) anodes, however the effect of carbons with different crystallinities and pore structures on their electrochemical performance remains controversial. We used pitch and phenolic resin (PR) as the precursors of ordered and disordered carbon, respectively, to prepare carbon-coated silicon (Si@C) with strictly controlled carbon contents and surface functional groups. Their electrochemical behavior was investigated. An ordered crystalline structure is favorable for electron transport, and mesopores and macropores are conducive to the diffusion of lithium ions. Such a coating with a small pore volume is an excellent buffer for the expansion of Si, and the electrode maintains structural integrity for 50 cycles. A disordered porous structure is less robust and produces a large polarization, which produces continuous volume expansion with cycling and leads to inferior electrochemical performance. As a result, the capacity and capacity retention after 100 cycles at 0.5 A g−1 of Si@C-Pitch are respectively 8 times and 1.9 times those of Si@C-PR. This study provides theoretical guidance for the selection of carbon materials used in Si@C anodes.
Ni(OH)2/石墨相氮化碳/石墨烯三元复合材料的制备及电化学性能
王艳敏, 马倩, 刘斌, 崔金龙, 张永强, 赫文秀
, doi: 10.1016/S1872-5805(22)60625-5
摘要(59) HTML(67) PDF(30)
摘要:
通过水热法制备Ni(OH)2/石墨相氮化碳(g-C3N4)/石墨烯(RGO)三元复合材料,研究了Ni(OH)2∶g-C3N4∶RGO质量比对复合材料结构、形貌和电化学性能的影响。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅里叶转换红外光谱仪(FT-IR)、氮气物理吸脱附仪、透射电子显微镜(TEM)等测试手段表征材料的微观结构和还原程度,采用循环伏安(CV)、恒流充放电(GCD)及电化学交流阻抗(EIS)测试复合材料的电化学性能。结果表明:当Ni(OH)2∶g-C3N4∶RGO=16∶1∶1(质量比)时三元复合材料为三维片层空间互相交错结构,氧化峰和还原峰的电位差ΔE为0.218 V。当电流密度为1 A/g时,复合材料的比电容为516.9 F/g,充放电3000次循环后,容量保持率达74.3%,显示出良好的电化学性能。 通过水热法制备Ni(OH)2/石墨相氮化碳(g-C3N4)/石墨烯(RGO)三元复合材料,研究了Ni(OH)2∶g-C3N4∶RGO质量比对复合材料结构、形貌和电化学性能的影响。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅里叶转换红外光谱仪(FT-IR)、氮气物理吸脱附仪、透射电子显微镜(TEM)等测试手段表征材料的微观结构和还原程度,采用循环伏安(CV)、恒流充放电(GCD)及电化学交流阻抗(EIS)测试复合材料的电化学性能。结果表明:当Ni(OH)2∶g-C3N4∶RGO=16∶1∶1(质量比)时三元复合材料为三维片层空间互相交错结构,氧化峰和还原峰的电位差ΔE为0.218 V。当电流密度为1 A/g时,复合材料的比电容为516.9 F/g,充放电3000次循环后,容量保持率达74.3%,显示出良好的电化学性能。
Coal-based graphene as a promoter of TiO2 for photocatalytic degradation of organic dyes
LIU Guo-yang, LI Ke-ke, JIA Jia, ZHANG Ya-ting
, doi: 10.1016/S1872-5805(21)60047-1
摘要(674) HTML(377) PDF(60)
摘要:
Graphene oxide (GO) obtained by the Hummers method from coal-based graphite was composited with TiO2 by hydrothermal and wet mixing methods to obtain (H-rGO)/TiO2 and M-TiO2/rGO composites, respectively, which were used as catalysts for photocatalytic degradation of rhodamine B (Rh B) and methyl orange (MO). Compared with the M-TiO2/GO and M-TiO2/rGO composites, the TiO2 nanoparticles in H-TiO2/rGO were more uniformly decorated on both sides of rGO sheets, forming a stacked-sheet structure while apparent aggregation of TiO2 nanoparticles was found in both M-TiO2/GO and M-TiO2/rGO. H-rGO@TiO2 had the highest catalytic activity towards degradation of Rh B and MO under visible light irradiation among the three, where the incorporation of rGO into TiO2 helps to narrow the band gap of TiO2, inhibits the recombination rate of electron–hole pairs and provides conductive networks for electron transfer. Graphene oxide (GO) obtained by the Hummers method from coal-based graphite was composited with TiO2 by hydrothermal and wet mixing methods to obtain (H-rGO)/TiO2 and M-TiO2/rGO composites, respectively, which were used as catalysts for photocatalytic degradation of rhodamine B (Rh B) and methyl orange (MO). Compared with the M-TiO2/GO and M-TiO2/rGO composites, the TiO2 nanoparticles in H-TiO2/rGO were more uniformly decorated on both sides of rGO sheets, forming a stacked-sheet structure while apparent aggregation of TiO2 nanoparticles was found in both M-TiO2/GO and M-TiO2/rGO. H-rGO@TiO2 had the highest catalytic activity towards degradation of Rh B and MO under visible light irradiation among the three, where the incorporation of rGO into TiO2 helps to narrow the band gap of TiO2, inhibits the recombination rate of electron–hole pairs and provides conductive networks for electron transfer.
炭纸衬底上化学气相沉积直立型二维过渡金属硫化物及其电催化产氢性能
王克, 汤飞, 姚孝璋, HitanshuKumar, 干林
, doi: 10.1016/S1872-5805(21)60078-1
摘要(46) HTML(27) PDF(11)
摘要:
以MoS2为代表的二维过渡金属硫化物近年来在电催化水分解产氢反应(HER)中表现出良好的电催化活性而受到广泛关注。但二维过渡金属硫化物的导电性一般较差、且催化活性位常在有限的边缘位置,成为限制其催化性能的重要因素。本文通过化学气相沉积方法研究了在炭纸基底上直接生长3种过渡金属硫化物(MoS2、NbS2和WS2)构筑一体化催化电极,以提高整个电极的导电性。通过优化生长工艺,实现了炭纸表面3种过渡金属硫化物的直立型生长并对电催化产氢反应表现出良好的催化性能,尤其是WS2表现出新颖的纳米片/纳米纤维层次结构,其对产氢反应表现出最佳的催化性能。在此基础上,对炭纸上生长的过渡金属硫化物通过阴极电化学活化处理的方式引入硫缺陷,从而提高其HER活性。结合透射电子显微镜和原位电化学拉曼光谱仪研究了二维过渡金属硫化物在电化学活化前后的结构变化尤其是所产生的硫缺陷的微观结构,为其产氢性能的提升提供合理的解释。 以MoS2为代表的二维过渡金属硫化物近年来在电催化水分解产氢反应(HER)中表现出良好的电催化活性而受到广泛关注。但二维过渡金属硫化物的导电性一般较差、且催化活性位常在有限的边缘位置,成为限制其催化性能的重要因素。本文通过化学气相沉积方法研究了在炭纸基底上直接生长3种过渡金属硫化物(MoS2、NbS2和WS2)构筑一体化催化电极,以提高整个电极的导电性。通过优化生长工艺,实现了炭纸表面3种过渡金属硫化物的直立型生长并对电催化产氢反应表现出良好的催化性能,尤其是WS2表现出新颖的纳米片/纳米纤维层次结构,其对产氢反应表现出最佳的催化性能。在此基础上,对炭纸上生长的过渡金属硫化物通过阴极电化学活化处理的方式引入硫缺陷,从而提高其HER活性。结合透射电子显微镜和原位电化学拉曼光谱仪研究了二维过渡金属硫化物在电化学活化前后的结构变化尤其是所产生的硫缺陷的微观结构,为其产氢性能的提升提供合理的解释。
Preparation of Co-loaded ceramic-based microwave absorbing composites for use in microwave absorption using gangue as a reduction agent and precursor of carbon/ceramic components
LI Guo-min, SHI Shu-ping, ZHU Bao-shun, LIANG Li-ping, ZHANG Ke-wei
, doi: 10.1016/S1872-5805(21)60064-1
摘要(151) HTML(91) PDF(69)
摘要:
In the context of sustainable development, tackling the severe solid waste pollutions has become extremely urgent. Herein, the solid waste gangue was used to synthesize the ceramic-based microwave absorbing composites decorated with Co particles by a novel synthesis method, where the magnetic Co particles were uniformly loaded in the ceramic matrix by pelletizing gangue accompanied by spraying a solution containing Co2+, followed by in-situ carbothermal reduction using the fixed carbon in gangue as the reduction agent. The Co contents in ceramic composites are precisely controlled by adjusting the Co2+ concentration in the solutions. The fixed carbon in gangue is partially consumed and there are residue carbons in the composites, which have more defects as compared with that in gangue and play an important role as an dielectric constitute. Compared with gangue, the optimized composite exhibits excellent microwave absorbing properties with the minimum reflection loss value of −48.2 dB and the effective absorbing band of 4.3 GHz under a coating thickness of 1.5 mm. which is mainly attributed to the enhanced magnetic loss and multiple interface polarization in the composite. Such use of gangue in this work can effectively realize the resource utilization and production of low-cost and light-weight of microwave absorbing materials. In the context of sustainable development, tackling the severe solid waste pollutions has become extremely urgent. Herein, the solid waste gangue was used to synthesize the ceramic-based microwave absorbing composites decorated with Co particles by a novel synthesis method, where the magnetic Co particles were uniformly loaded in the ceramic matrix by pelletizing gangue accompanied by spraying a solution containing Co2+, followed by in-situ carbothermal reduction using the fixed carbon in gangue as the reduction agent. The Co contents in ceramic composites are precisely controlled by adjusting the Co2+ concentration in the solutions. The fixed carbon in gangue is partially consumed and there are residue carbons in the composites, which have more defects as compared with that in gangue and play an important role as an dielectric constitute. Compared with gangue, the optimized composite exhibits excellent microwave absorbing properties with the minimum reflection loss value of −48.2 dB and the effective absorbing band of 4.3 GHz under a coating thickness of 1.5 mm. which is mainly attributed to the enhanced magnetic loss and multiple interface polarization in the composite. Such use of gangue in this work can effectively realize the resource utilization and production of low-cost and light-weight of microwave absorbing materials.
咖啡渣成型制备生物质炭及其CH4/N2分离性能
高雨舟, 徐爽, 王成通, 张雪洁, 刘汝帅, 陆安慧
, doi: 10.1016/S1872-5805(22)60626-7
摘要(71) HTML(69) PDF(20)
摘要:
本文以咖啡渣为原料,硅酸钠为黏结剂和造孔剂,通过挤条成型技术制备柱状炭前驱体,经高温炭化活化和碱洗除硅,获得高强度柱状多孔炭吸附剂(CGCs),研究其CH4/N2的吸附分离性能。红外光谱分析结果显示CGC-1.5含有丰富的含氧官能团。CGCs的比表面积和孔容积随着前驱体中硅酸钠含量的增加而增大,其中9%硅酸钠溶液与原料质量比为1.5的样品CGC-1.5的比表面积为527 m2·g−1,总孔容为0.33 cm3·g−1。氮吸附等温线和CO2吸附等温线分析结果表明CGCs含有丰富的微孔、介孔以及(个别样品)大孔,微孔主要集中在0.48 nm左右。在298 K和0.1 MPa条件下CGC-1.5对CH4的平衡吸附量为0.87 mmol·g−1,CH4/N2 (3/7)的IAST分离选择性达到10.3,优于多数生物质基多孔炭固体吸附剂和晶态材料。双组份动态穿透测试结果证实该材料在常压和加压条件均具有优异的CH4/N2动态分离性能,298 K时0.11 MPa和0.5 MPa条件下的动态选择性分别达到10.4和17.9,经10次吸-脱附循环测试,吸附量保持不变。CGC-1.5的机械强度高达123 N·cm−1,具有潜在的工业应用前景。 本文以咖啡渣为原料,硅酸钠为黏结剂和造孔剂,通过挤条成型技术制备柱状炭前驱体,经高温炭化活化和碱洗除硅,获得高强度柱状多孔炭吸附剂(CGCs),研究其CH4/N2的吸附分离性能。红外光谱分析结果显示CGC-1.5含有丰富的含氧官能团。CGCs的比表面积和孔容积随着前驱体中硅酸钠含量的增加而增大,其中9%硅酸钠溶液与原料质量比为1.5的样品CGC-1.5的比表面积为527 m2·g−1,总孔容为0.33 cm3·g−1。氮吸附等温线和CO2吸附等温线分析结果表明CGCs含有丰富的微孔、介孔以及(个别样品)大孔,微孔主要集中在0.48 nm左右。在298 K和0.1 MPa条件下CGC-1.5对CH4的平衡吸附量为0.87 mmol·g−1,CH4/N2 (3/7)的IAST分离选择性达到10.3,优于多数生物质基多孔炭固体吸附剂和晶态材料。双组份动态穿透测试结果证实该材料在常压和加压条件均具有优异的CH4/N2动态分离性能,298 K时0.11 MPa和0.5 MPa条件下的动态选择性分别达到10.4和17.9,经10次吸-脱附循环测试,吸附量保持不变。CGC-1.5的机械强度高达123 N·cm−1,具有潜在的工业应用前景。
Oxygen-incorporated carbon nitride porous nanosheets for highly efficient photoelectrocatalytic CO2 reduction to formate
WANG Hong-zhi, ZHAO Yue-zhu, YANG Zhong-xue, BI Xin-ze, WANG Zhao-liang, WU Ming-bo
, doi: 10.1016/S1872-5805(22)60619-X
摘要(115) HTML(66) PDF(27)
摘要:
Using CO2 as a renewable carbon source for the production of high-value-added fuels and chemicals has drawn global attention lately. Photoelectrocatalytic (PEC) CO2 reduction (CO2RR) is one of the most realistic and attractive way, which can be realized effectively under sunlight illumination at low overpotential. Here, oxygen-incorporated carbon nitride (CNs) porous nanosheets were synthesized, which were used as photoanodes with Bi2CuO4 as the photocathode to realize the PEC CO2 reduction to formate. The electrical conductivity and the photoelectric response of CNs were tailored by changing the oxygen source. The oxygen obtained from the oxygen-containing precursor could improve the conductivity due to the more negative electronegativity. The oxygen obtained from the calcination atmosphere has lower photoelectric response due to the energy band structure. Under the optimal conditions, the CN has a photocurrent density of 587 μA cm−2 and an activity of PEC CO2 reduction to formate of 273.56 µmol cm−2 h−1, which is nearly 19 times higher than that of the conventional sample. Moreover, the optimal CN sample shows excellent stability with the photocurrent kept constant for 24 h. This work provides a new avenue to achieve catalysts efficient for PEC CO2 reduction to formate, which may be expanded to different PEC reactions using different cathode catalysts.ode catalysts. Using CO2 as a renewable carbon source for the production of high-value-added fuels and chemicals has drawn global attention lately. Photoelectrocatalytic (PEC) CO2 reduction (CO2RR) is one of the most realistic and attractive way, which can be realized effectively under sunlight illumination at low overpotential. Here, oxygen-incorporated carbon nitride (CNs) porous nanosheets were synthesized, which were used as photoanodes with Bi2CuO4 as the photocathode to realize the PEC CO2 reduction to formate. The electrical conductivity and the photoelectric response of CNs were tailored by changing the oxygen source. The oxygen obtained from the oxygen-containing precursor could improve the conductivity due to the more negative electronegativity. The oxygen obtained from the calcination atmosphere has lower photoelectric response due to the energy band structure. Under the optimal conditions, the CN has a photocurrent density of 587 μA cm−2 and an activity of PEC CO2 reduction to formate of 273.56 µmol cm−2 h−1, which is nearly 19 times higher than that of the conventional sample. Moreover, the optimal CN sample shows excellent stability with the photocurrent kept constant for 24 h. This work provides a new avenue to achieve catalysts efficient for PEC CO2 reduction to formate, which may be expanded to different PEC reactions using different cathode catalysts.ode catalysts.
Incorporation of TiO2 nanoparticles into multichannels of electrospun carbon fibers for enhancing adsorption of polysulfides in room temperature sodium-sulfur batteries
YE Xin, LI Zhi-qi, SUN Hao, WU Ming-xia, AN Zhong-xun, PANG Yue-peng, YANG Jun-he, ZHENG Shi-you
, doi: 10.1016/S1872-5805(22)60607-3
摘要(93) HTML(57) PDF(34)
摘要:
With the rapid development of electric vehicles and large-scale power grids, lithium-ion batteries inevitably face the dilemma in that the limited energy density and high cost fail to meet the growing demand. Room temperature sodium-sulfur (RT Na-S) batteries, which have the potential to replace lithium-ion batteries, have become the focus of attention. However, the challenging problem of poor cycling performance arising from “shuttle effect” of the reaction intermediates (sodium polysulfides) needs to be addressed. We report a method to incorporate TiO2 nano particles into multichannels of electrospun carbon fibers (TiO2@MCCFs) to stabilize sulfur compounds to produce high-performance RT Na-S batteries. The TiO2@MCCFs were prepared by electrospinning followed by heat treatment, which were infiltrated by molten sulfur to fabricate S/TiO2@MCCF cathode materials. The addition of TiO2 nanoparticles enhances the affinity to polysulfides and promotes the conversion of polysulfides to lower order products, which was verified by DFT calculations. The S/TiO2@MCCF cathode with a S content of 54% has improved electrochemical performance with a specific capacity of 445.1 mAh g−1 after 100 cycles at 0.1 A g−1 and a nearly 100% Coulombic efficiency. Even at 2 A g−1, the cathode still exhibits a capacity of 300.5 mAh g−1 after 500 cycles, demonstrating excellent rate and cycling performance. This work provides a new way to construct high performance RT Na-S battery cathodes. With the rapid development of electric vehicles and large-scale power grids, lithium-ion batteries inevitably face the dilemma in that the limited energy density and high cost fail to meet the growing demand. Room temperature sodium-sulfur (RT Na-S) batteries, which have the potential to replace lithium-ion batteries, have become the focus of attention. However, the challenging problem of poor cycling performance arising from “shuttle effect” of the reaction intermediates (sodium polysulfides) needs to be addressed. We report a method to incorporate TiO2 nano particles into multichannels of electrospun carbon fibers (TiO2@MCCFs) to stabilize sulfur compounds to produce high-performance RT Na-S batteries. The TiO2@MCCFs were prepared by electrospinning followed by heat treatment, which were infiltrated by molten sulfur to fabricate S/TiO2@MCCF cathode materials. The addition of TiO2 nanoparticles enhances the affinity to polysulfides and promotes the conversion of polysulfides to lower order products, which was verified by DFT calculations. The S/TiO2@MCCF cathode with a S content of 54% has improved electrochemical performance with a specific capacity of 445.1 mAh g−1 after 100 cycles at 0.1 A g−1 and a nearly 100% Coulombic efficiency. Even at 2 A g−1, the cathode still exhibits a capacity of 300.5 mAh g−1 after 500 cycles, demonstrating excellent rate and cycling performance. This work provides a new way to construct high performance RT Na-S battery cathodes.
Microstructures and electrochemical properties of coconut shell-based hard carbons as anode materials for potassium ion batteries
HUANG Tao, PENG Da-chun, CHEN Zui, XIA Xiao-hong, CHEN Yu-xi, LIU Hong-bo
, doi: 10.1016/S1872-5805(21)60069-0
摘要(979) HTML(477) PDF(89)
摘要:
Biomorphic hard carbons have attracted widely interest as anode materials for potassium ion batteries (PIBs) recently owing to their high reversible capacity. But, the high preparation cost and poor cycle stability significantly hinder their practical applications. In this study, coconut shell-derived hard carbon (CSHCs) were prepared from waste biomass coconut shell using a one-step carbonization method, which were used as anode materials for potassium ion batteries. The effects of the carbonization temperature on the microstructures and electrochemical properties of the CSHCs were investigated by X-ray diffraction, nitrogen adsorption, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and cyclic voltammetry, etc. Results indicate that the CSHC carbonized at 1 000 °C (CSHC-10) possesses a suitable graphite microcrystalline size, pore structure and surface defect content, which exhibits the best electrochemical performance. Specifically, it presents a high reversible specific capacity of 254 mAh·g−1 at 30 mA·g−1 with an initial Coulombic efficiency of 75.0%, and the capacity retention rates are 87.5% after 100 cycles and 75.9% after 400 cycles at 100 mA·g−1, demonstrating its excellent potassium storage performance. Biomorphic hard carbons have attracted widely interest as anode materials for potassium ion batteries (PIBs) recently owing to their high reversible capacity. But, the high preparation cost and poor cycle stability significantly hinder their practical applications. In this study, coconut shell-derived hard carbon (CSHCs) were prepared from waste biomass coconut shell using a one-step carbonization method, which were used as anode materials for potassium ion batteries. The effects of the carbonization temperature on the microstructures and electrochemical properties of the CSHCs were investigated by X-ray diffraction, nitrogen adsorption, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and cyclic voltammetry, etc. Results indicate that the CSHC carbonized at 1 000 °C (CSHC-10) possesses a suitable graphite microcrystalline size, pore structure and surface defect content, which exhibits the best electrochemical performance. Specifically, it presents a high reversible specific capacity of 254 mAh·g−1 at 30 mA·g−1 with an initial Coulombic efficiency of 75.0%, and the capacity retention rates are 87.5% after 100 cycles and 75.9% after 400 cycles at 100 mA·g−1, demonstrating its excellent potassium storage performance.
Preparation and lithium storage property of anthracite-based graphite anode materials
LI Yuan, TIAN Xiao-dong, SONG Yan, YANG Tao, WU Shi-jie, LIU Zhan-jun
, doi: 10.1016/S1872-5805(21)60057-4
摘要(301) HTML(215) PDF(75)
摘要:
In this work, graphites with various microstructures were prepared by cost-effective anthracite and industrial silicon powder as precursor and catalyst, respectively. The mechanism of catalytic reaction and the electrochemical properties of the as-prepared coal-based graphite as lithium anode were investigated. The correlation between structure and properties of graphite was discussed. The results demonstrate that the as-obtained sample with 5% silicon catalyst (G-2800-5%) exhibits the best overall lithium storage performance. In detail, G-2800-5% displays the best graphite structure with graphitization degree of 91.5%. As anode materials, a high reversible capacity of 369.0 mAh g−1 can be achieved at 0.1 A g−1. Meanwhile, the reversible capacity of 209.0 mAh g−1 can be obtained at the current density of 1 A g−1. It also delivers good cyclic stability with the retention rate of 92.2% after 200 cycles at 0.2 A g−1. The highly developed graphite structure, which is favorable to the formation of stable SEI and reduces lithium ion loss should be responsible for the superior electrochemical performance. In this work, graphites with various microstructures were prepared by cost-effective anthracite and industrial silicon powder as precursor and catalyst, respectively. The mechanism of catalytic reaction and the electrochemical properties of the as-prepared coal-based graphite as lithium anode were investigated. The correlation between structure and properties of graphite was discussed. The results demonstrate that the as-obtained sample with 5% silicon catalyst (G-2800-5%) exhibits the best overall lithium storage performance. In detail, G-2800-5% displays the best graphite structure with graphitization degree of 91.5%. As anode materials, a high reversible capacity of 369.0 mAh g−1 can be achieved at 0.1 A g−1. Meanwhile, the reversible capacity of 209.0 mAh g−1 can be obtained at the current density of 1 A g−1. It also delivers good cyclic stability with the retention rate of 92.2% after 200 cycles at 0.2 A g−1. The highly developed graphite structure, which is favorable to the formation of stable SEI and reduces lithium ion loss should be responsible for the superior electrochemical performance.
A flexible hard carbon microsphere/MXene film as a high-performance anode for sodium-ion storage
CAO Hai-liang, YANG Liang-tao, ZHAO Min, LIU Pei-zhi, GUO Chun-li, XU Bing-she, GUO Jun-jie
, doi: 10.1016/S1872-5805(22)60616-4
摘要(138) HTML(84) PDF(33)
摘要:
Hard carbon is considered the most promising anode material for sodium-ion batteries, but its volume change during sodiation/desodiation limits its cycle life. Hard carbon microspheres (HCSs) with no binder were composited with a MXene film to form an electrode and its sodium storage properties were studied. The microspheres were prepared using Shanxi aged vinegar as a liquid carbon source. Two-dimensional Ti3C2Tx MXene (T is a functional group) was used as a multifunctional conductive binder to fabricate the flexible electrodes. Remarkably, because of the three-dimensional conductive network, the HCS/Ti3C2Tx film electrode has a high capacity of 346 mAh g−1, excellent rate performance and outstanding cycling stability over 1 000 cycles. This remarkable electrochemical performance indicates that the flexible film is a very promising anode for next-generation sodium-ion batteries. Hard carbon is considered the most promising anode material for sodium-ion batteries, but its volume change during sodiation/desodiation limits its cycle life. Hard carbon microspheres (HCSs) with no binder were composited with a MXene film to form an electrode and its sodium storage properties were studied. The microspheres were prepared using Shanxi aged vinegar as a liquid carbon source. Two-dimensional Ti3C2Tx MXene (T is a functional group) was used as a multifunctional conductive binder to fabricate the flexible electrodes. Remarkably, because of the three-dimensional conductive network, the HCS/Ti3C2Tx film electrode has a high capacity of 346 mAh g−1, excellent rate performance and outstanding cycling stability over 1 000 cycles. This remarkable electrochemical performance indicates that the flexible film is a very promising anode for next-generation sodium-ion batteries.
碘化钾调控孔结构的石墨烯及其电化学电容器应用
罗明宇, 徐若谷, 石颖, 王宇作, 李峰
, doi: 10.1016/S1872-5805(23)60714-0
摘要(13) HTML(2) PDF(6)
摘要:
较低的体积能量密度限制了当前电化学电容器的应用,而提高体积能量密度的关键在于发展具有致密化储能特性的多孔碳材料。目前,毛细致密化已成为平衡多孔碳密度和孔隙率从而提高材料体积比电容的主要方法,但仍在孔结构的精细调控方面存在不足,制约了毛细致密化多孔碳与高电压离子液体的兼容性。本文提出了碘化钾辅助的毛细致密化策略,通过在石墨烯网络中预载碘化钾来控制毛细致密化过程,实现了对孔结构的有效调控。同时电化学性能表征结果表明碘化钾具有增加离子可及表面积和提供赝电容的作用。基于此,所制备的碘化钾/石墨烯材料的密度可达到0.96 g cm−3,在离子液体中的体积比电容可达到115 F cm−3。由该材料所组装的电化学电容器可以提供19.6 Wh L−1的体积能量密度。 较低的体积能量密度限制了当前电化学电容器的应用,而提高体积能量密度的关键在于发展具有致密化储能特性的多孔碳材料。目前,毛细致密化已成为平衡多孔碳密度和孔隙率从而提高材料体积比电容的主要方法,但仍在孔结构的精细调控方面存在不足,制约了毛细致密化多孔碳与高电压离子液体的兼容性。本文提出了碘化钾辅助的毛细致密化策略,通过在石墨烯网络中预载碘化钾来控制毛细致密化过程,实现了对孔结构的有效调控。同时电化学性能表征结果表明碘化钾具有增加离子可及表面积和提供赝电容的作用。基于此,所制备的碘化钾/石墨烯材料的密度可达到0.96 g cm−3,在离子液体中的体积比电容可达到115 F cm−3。由该材料所组装的电化学电容器可以提供19.6 Wh L−1的体积能量密度。
Chemically Transformed Encapsulation of Sulfur inside Hierarchical Micro-nano Carbon/Molybdenum Carbide for High-Performance Li-S batteries
CHEN Xin-Rong, YU Xiao-Fei, HE Bin, LI Wen-Cui
, doi: 10.1016/S1872-5805(23)60713-9
摘要(16) HTML(12) PDF(1)
摘要:
Tailor-made fabrication of sulfur host is very effective for solving the main challenges of lithium-sulfur (Li-S) batteries, such as the shuttle effect and sluggish redox kinetics, due to that sulfur host as a reactor for redox reactions determines the electrochemical properties of the sulfur cathode. Under this guidance, sulfur is in-situ confined in a hollow thin-walled C/Mo2C reactor with size smaller than 7 nm, in which these nanosized primary particles are connected each other to form secondary microsized particles. In such composites, the nanoscale sulfur core and continuous conductive network can facilitate lithium-ion and electron transport. Moreover, the microporous C/Mo2C shell can mitigate the outward diffusion of polysulfides via the physical/chemical obstruction and enhance redox kinetics by effectively catalytic conversion of polysulfides. Stem from these merits, the S@C/Mo2C cathode materials can achieve a high reversible capacity of 1210 mA h g−1 at 0.5 C with a low capacity fading rate of 0.127% per cycle over 300 cycles and high rate performance (780 mA h g−1 at 3.0 C). The present work may shed light on designing advanced sulfur host for Li-S batteries with high rate performance and high cycle stability. Tailor-made fabrication of sulfur host is very effective for solving the main challenges of lithium-sulfur (Li-S) batteries, such as the shuttle effect and sluggish redox kinetics, due to that sulfur host as a reactor for redox reactions determines the electrochemical properties of the sulfur cathode. Under this guidance, sulfur is in-situ confined in a hollow thin-walled C/Mo2C reactor with size smaller than 7 nm, in which these nanosized primary particles are connected each other to form secondary microsized particles. In such composites, the nanoscale sulfur core and continuous conductive network can facilitate lithium-ion and electron transport. Moreover, the microporous C/Mo2C shell can mitigate the outward diffusion of polysulfides via the physical/chemical obstruction and enhance redox kinetics by effectively catalytic conversion of polysulfides. Stem from these merits, the S@C/Mo2C cathode materials can achieve a high reversible capacity of 1210 mA h g−1 at 0.5 C with a low capacity fading rate of 0.127% per cycle over 300 cycles and high rate performance (780 mA h g−1 at 3.0 C). The present work may shed light on designing advanced sulfur host for Li-S batteries with high rate performance and high cycle stability.
Effects of Polyurethane Sizing Agent on Interfacial Properties of Carbon Fiber Reinforced Polyurethane Composites
LI Sheng-xia, YANG Chang-ling, YAO Li-li, WU Bo, LU Yong-gen
, doi: 10.1016/S1872-5805(23)60705-X
摘要(10) HTML(14) PDF(1)
摘要:
An anodized carbon fiber tow is sized continuously. The effects of aqueous polyurethane as the sizing agent for enhancing the interfacial properties of carbon fiber reinforced polyurethane composite is investigated based on interlaminar shear strength (ILSS), elemental and functional group analysis, thermal gravimetric analysis and differential scanning calorimetry. The results show the polyurethane as the sizing agent of carbon fiber can significantly improve the interfacial properties of the composites. The ILSS of the sized carbon fiber reinforced composite is increased by 17.5%, from 39.5 MPa to 46.4 MPa compared with that the oxidized carbon fiber reinforced. Treating the sized carbon fiber reinforced composite at 170 °C can further increase the ILSS by 9.5%, to 50.8 MPa. It is considered the sizing agent can form chemical binding with the oxygen-contained functional groups on the oxidized carbon fiber surface and form hydrogen bonds with the matrix resin. After heat treatment at 170 °C, the blocking groups in the sizing agent are unblocked to reveal the isocyanate roots that react with the carbamate of the matrix to form allophanate. It can be concluded that the polyurethane sizing agent is suitable for improving the interface performance of carbon fiber reinforced polyurethane resin composites. Unsealing the sizing agent at high temperature treatment after curing can further improve the interface performance of the composite. An anodized carbon fiber tow is sized continuously. The effects of aqueous polyurethane as the sizing agent for enhancing the interfacial properties of carbon fiber reinforced polyurethane composite is investigated based on interlaminar shear strength (ILSS), elemental and functional group analysis, thermal gravimetric analysis and differential scanning calorimetry. The results show the polyurethane as the sizing agent of carbon fiber can significantly improve the interfacial properties of the composites. The ILSS of the sized carbon fiber reinforced composite is increased by 17.5%, from 39.5 MPa to 46.4 MPa compared with that the oxidized carbon fiber reinforced. Treating the sized carbon fiber reinforced composite at 170 °C can further increase the ILSS by 9.5%, to 50.8 MPa. It is considered the sizing agent can form chemical binding with the oxygen-contained functional groups on the oxidized carbon fiber surface and form hydrogen bonds with the matrix resin. After heat treatment at 170 °C, the blocking groups in the sizing agent are unblocked to reveal the isocyanate roots that react with the carbamate of the matrix to form allophanate. It can be concluded that the polyurethane sizing agent is suitable for improving the interface performance of carbon fiber reinforced polyurethane resin composites. Unsealing the sizing agent at high temperature treatment after curing can further improve the interface performance of the composite.
Molecular structure effect of naphthalene-based mesophase pitches on the properties of their carbon fibers
XU Hui-tao, GUO Jian-guang, LI Wen-long, LI Xuan-ke
, doi: 10.1016/S1872-5805(23)60709-7
摘要(17) HTML(19) PDF(3)
摘要:
Mesophase pitch-based carbon fibers (MPCFs) have the characteristics of high modulus, low resistivity and high thermal conductivity, so it has broad application prospects in many fields. High-performance carbon fibers were prepared from naphthalene-based mesophase pitches synthesized by HF/BF3 catalytic one-step method (AR-MP) and AlCl3 catalytic two-step method (N-MP), respectively. These two mesophase pitches, and spun pitch fibers, pre-oxidized fibers carbonized fibers and graphitized fibers produced from them were characterized by TG-MS, FT-IR, 13 C-NMR, MALDI-TOF-MS, XRD, SEM and elemental analysis. The molecular structures and properties of mesophase pitches prepared by different catalytic polymerization processes were compared, and the effects of molecular structure differences of mesophase pitches on the structure and properties of carbon fibers were further explored. In comparison to N-MP, AR-MP possesses a rod-like semi-rigid molecular configuration containing more naphthenic structures and methyl side chains. The pre-oxidized fibers derived from AR-MP show better carbon layer orientation, thus their graphitized fibers have higher thermal conductivity of 716 W/m·K. N-MP with higher aromaticity possesses a disc-like rigid molecular configuration. Therefore, the graphitized fibers prepared from N-MP have higher tensile strength of 3.47 GPa due to their fewer resulted defects during the preparation. The molecular structures of AR-MP and N-MP have an obvious influence on the structure and properties of their graphited fibers. Mesophase pitch-based carbon fibers (MPCFs) have the characteristics of high modulus, low resistivity and high thermal conductivity, so it has broad application prospects in many fields. High-performance carbon fibers were prepared from naphthalene-based mesophase pitches synthesized by HF/BF3 catalytic one-step method (AR-MP) and AlCl3 catalytic two-step method (N-MP), respectively. These two mesophase pitches, and spun pitch fibers, pre-oxidized fibers carbonized fibers and graphitized fibers produced from them were characterized by TG-MS, FT-IR, 13 C-NMR, MALDI-TOF-MS, XRD, SEM and elemental analysis. The molecular structures and properties of mesophase pitches prepared by different catalytic polymerization processes were compared, and the effects of molecular structure differences of mesophase pitches on the structure and properties of carbon fibers were further explored. In comparison to N-MP, AR-MP possesses a rod-like semi-rigid molecular configuration containing more naphthenic structures and methyl side chains. The pre-oxidized fibers derived from AR-MP show better carbon layer orientation, thus their graphitized fibers have higher thermal conductivity of 716 W/m·K. N-MP with higher aromaticity possesses a disc-like rigid molecular configuration. Therefore, the graphitized fibers prepared from N-MP have higher tensile strength of 3.47 GPa due to their fewer resulted defects during the preparation. The molecular structures of AR-MP and N-MP have an obvious influence on the structure and properties of their graphited fibers.
Topography changes and microstructural evolution of nuclear graphite (IG-110) induced by Xe26+ irradiation
ZHANG He-yao, SONG Jin-liang, YIN Hui-qin, TANG Zhong-feng, LIU Zhan-jun, LIU Xiang-dong
, doi: 10.1016/S1872-5805(23)60708-5
摘要(7) HTML(10) PDF(0)
摘要:
As a key material in nuclear reactors, nuclear graphite is affected by the high-flux irradiation in the reactor, and its irradiation behavior is an important factor for the reactor operation. In order to understand the irradiation behavior of nuclear graphite, IG-110 nuclear graphite, as a representative of nuclear graphite, was chosen to study the evolution of morphology and microstructure caused by 7 MeV Xe26+ irradiation. The topography and microstructure changes of IG-110 were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, Raman spectroscopy and nano-indentation, respectively. The ridge-like structure on the surface of the IG-110 graphite, mainly the binder region, and the roughness increases slowly. As the irradiation damage dose increases, the ridge-like structure also appears in the filler region. The shrinkage of pores increases and its distribution is discrete. The roughness also increases rapidly as the pores close. The changes in topography and microstructure of IG-110 graphite caused by irradiation are attributed to the expansion of graphite along the C-axis direction. Defect density and the degree of in-plane disorder in the graphitic structure increases with the increase of irradiation damage dose. The mechanical properties of IG-110 graphite increase with increasing neutron fluence due to dislocation pinning and a closure of the fine pores. At higher irradiation dose, the mechanical properties reduce, which is attributed to the generation of internal porosity or amorphous structure. As a key material in nuclear reactors, nuclear graphite is affected by the high-flux irradiation in the reactor, and its irradiation behavior is an important factor for the reactor operation. In order to understand the irradiation behavior of nuclear graphite, IG-110 nuclear graphite, as a representative of nuclear graphite, was chosen to study the evolution of morphology and microstructure caused by 7 MeV Xe26+ irradiation. The topography and microstructure changes of IG-110 were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, Raman spectroscopy and nano-indentation, respectively. The ridge-like structure on the surface of the IG-110 graphite, mainly the binder region, and the roughness increases slowly. As the irradiation damage dose increases, the ridge-like structure also appears in the filler region. The shrinkage of pores increases and its distribution is discrete. The roughness also increases rapidly as the pores close. The changes in topography and microstructure of IG-110 graphite caused by irradiation are attributed to the expansion of graphite along the C-axis direction. Defect density and the degree of in-plane disorder in the graphitic structure increases with the increase of irradiation damage dose. The mechanical properties of IG-110 graphite increase with increasing neutron fluence due to dislocation pinning and a closure of the fine pores. At higher irradiation dose, the mechanical properties reduce, which is attributed to the generation of internal porosity or amorphous structure.
Synthesis and electrochemical properties of nano-Si@C nanocomposite anodes for lithium-ion batteries
YUAN Li-ye, LYU Chun-xiang, LYU Xiao-xuan, YUAN Shu-xia, ZHANG Meng, CAO Li-juan, YANG Yu
, doi: 10.1016/S1872-5805(23)60707-3
摘要(21) HTML(16) PDF(4)
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The phenolic resin was coated on the surface of nano-Si by microencapsulation technology, and then carbonized under the Ar protection to prepare nano-Si@C nanocomposite. Firstly, four mass ratios of phenolic resin to nano-Si (1∶2, 1∶4, 1∶6, 1∶8) were employed to prepare nano-Si@C nanocomposites. The obtained average thickness of amorphous carbon coating was 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when the mass ratio of phenolic resin to nano Si was 1∶4, that is, the amorphous carbon coating was 4.5 nm.. The electrochemical properties of optimized nano-Si@C nanocomposite was then evaluated comprehensively, which exhibited excellent electrochemical performance as anode material for Li-ion batteries. Under a current density of 100 mAg−1, the nano-Si@C nanocomposite delivered a first discharge specific capacity of 2382 mAhg−1, first charge specific capacity of 1667 mAhg−1, and a first coulombic efficiency of 70%. Moreover, the discharge specific capacity of 835.6 mAhg−1 could be retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, nano-Si@C nanocomposite also demonstrated superior rate performance. Under the current densities of 100, 200, 500, 1000 and 2000 mAg−1, the average discharge specific capacities were 1716.4, 1231.6, 911.7, 676.1, and 339.8 mAhg−1, respectively. When the current density returned to 100 mAg−1, the specific capacity restored to 1326.4 mAhg−1. The phenolic resin was coated on the surface of nano-Si by microencapsulation technology, and then carbonized under the Ar protection to prepare nano-Si@C nanocomposite. Firstly, four mass ratios of phenolic resin to nano-Si (1∶2, 1∶4, 1∶6, 1∶8) were employed to prepare nano-Si@C nanocomposites. The obtained average thickness of amorphous carbon coating was 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when the mass ratio of phenolic resin to nano Si was 1∶4, that is, the amorphous carbon coating was 4.5 nm.. The electrochemical properties of optimized nano-Si@C nanocomposite was then evaluated comprehensively, which exhibited excellent electrochemical performance as anode material for Li-ion batteries. Under a current density of 100 mAg−1, the nano-Si@C nanocomposite delivered a first discharge specific capacity of 2382 mAhg−1, first charge specific capacity of 1667 mAhg−1, and a first coulombic efficiency of 70%. Moreover, the discharge specific capacity of 835.6 mAhg−1 could be retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, nano-Si@C nanocomposite also demonstrated superior rate performance. Under the current densities of 100, 200, 500, 1000 and 2000 mAg−1, the average discharge specific capacities were 1716.4, 1231.6, 911.7, 676.1, and 339.8 mAhg−1, respectively. When the current density returned to 100 mAg−1, the specific capacity restored to 1326.4 mAhg−1.
A Highly Efficient, Rapid, Room Temperature Synthesis of Coal-based Water-soluble Fluorescent Carbon Dots and Its Application in Fe3+ ion Detection
CHENG Zhong-fu, WU Xue-yan, LIU Lei, HE Long, YANG Zu-guo, CAO Chang, LV Yan, GUO Ji-xi
, doi: 10.1016/S1872-5805(23)60706-1
摘要(12) HTML(9) PDF(0)
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The present manuscript reports a coal-based fluorescent CDs which fabricated at room temperature through a friendly method with mixture of hydrogen peroxide (H2O2) and formic acid (HCOOH) as an oxidant instead of concentrated acid (HNO3 or H2SO4). The prepared CDs show the excitation dependent behavior with high QY approximately 7.2%. The as-made CDs are water soluble, robust photo-stability, good resistance to salt solution, insensitive to pH in a range of 2.0-12.0. The coal-based CDs served as a very sensitive nano-probe for the turn-off sensing of Fe3+ ion with a minimum LOD as low as 600 nM in a dynamic range 2 to 100 μM. This efficient, rapid synthesis of coal-based CDs will not only increase high value-added utilization of coal, but also have potential application value in sensing and several another analytical applications. The present manuscript reports a coal-based fluorescent CDs which fabricated at room temperature through a friendly method with mixture of hydrogen peroxide (H2O2) and formic acid (HCOOH) as an oxidant instead of concentrated acid (HNO3 or H2SO4). The prepared CDs show the excitation dependent behavior with high QY approximately 7.2%. The as-made CDs are water soluble, robust photo-stability, good resistance to salt solution, insensitive to pH in a range of 2.0-12.0. The coal-based CDs served as a very sensitive nano-probe for the turn-off sensing of Fe3+ ion with a minimum LOD as low as 600 nM in a dynamic range 2 to 100 μM. This efficient, rapid synthesis of coal-based CDs will not only increase high value-added utilization of coal, but also have potential application value in sensing and several another analytical applications.
Sulfonated graphene improves wear resistance of pantograph carbon slider materials under normal and wet conditions
ZHANG Si-si, TU Chuan-jun, LI Xiang, SONG Teng-hui, XIAN Yong, LIU Xin-long, SUN Heng, CHEN Yi-xing
, doi: 10.1016/S1872-5805(23)60704-8
摘要(9) HTML(10) PDF(0)
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In this study, a novel pantograph carbon slider (PCS) was designed by incorporating a sulfonated graphene (SG). This enhanced the mechanical and wear performances of the slider. The PCS was prepared through mold pressing, hot extrusion and roasting. A mock current-carrying wear test showed that the wear rate of the PCS reinforced by 1 wt % SG was lower by 50.0% in the normal environment and 51.0% in the rainy weather environment, compared with the control group. In addition, the flexural strength of samples with SG was higher by 41.8% compared to those without SG. Moreover, the dragging effect of SG decreased that number of random cracks and increased the compactness of fracture surface of slider materials. These changes markedly inhibited the electro-erosion of the PCS, thus improving mechanical and wear resistance significantly. In this study, a novel pantograph carbon slider (PCS) was designed by incorporating a sulfonated graphene (SG). This enhanced the mechanical and wear performances of the slider. The PCS was prepared through mold pressing, hot extrusion and roasting. A mock current-carrying wear test showed that the wear rate of the PCS reinforced by 1 wt % SG was lower by 50.0% in the normal environment and 51.0% in the rainy weather environment, compared with the control group. In addition, the flexural strength of samples with SG was higher by 41.8% compared to those without SG. Moreover, the dragging effect of SG decreased that number of random cracks and increased the compactness of fracture surface of slider materials. These changes markedly inhibited the electro-erosion of the PCS, thus improving mechanical and wear resistance significantly.
Recent Progress on Optimizing the Electromagnetic Wave Absorbing Performance of Carbon-based Materials: A Review
LI Wenyi, GAO Mingyang, MIAO Yang, WANG Xiaomin
, doi: 10.1016/S1872-5805(23)60703-6
摘要(136) HTML(21) PDF(9)
摘要:
The development of high-performance electromagnetic wave absorbing materials (EWAMs) posed a prospective way to solve electromagnetic wave radiation issues in both military and civil fields. The desirable EWAMs feature strong absorption intensity, broad bandwidth, lightweight, thin thicknesses as well as other exceptional properties such as oxygen resistance, wear resistance, high-temperature resistance and high strength. In these regards, carbon-based materials, including carbon nanostructures and carbonaceous composites have become the significant participants of EWAMs, standing out for their unique structures and properties compared with the other absorption materials. In this review, we summarized the recent inspiring achievements in carbon-based EWAMs involving different dimensional (0D, 1D, 2D and 3D) carbon nanostructures and various types of carbonaceous composites (binary dielectric-carbon composite, binary magnetic-carbon composite and heterogeneous composite). Firstly, the influential factors affecting the electromagnetic microwave absorption (EWA) performances involving conductivity \begin{document}$\sigma $\end{document}, permittivity \begin{document}$\varepsilon $\end{document}and permeability \begin{document}$ \mu $\end{document} were discussed based on the EWA mechanisms. Secondly, the representative reports and corresponding mechanisms about improving the EWA performance of carbon-based EWAMs were highlighted and analyzed in detail such as self-modification and composite structure construction. Finally, the current modification strategies and research prospects of carbon-based EWAMs were summarized and outlined. The development of high-performance electromagnetic wave absorbing materials (EWAMs) posed a prospective way to solve electromagnetic wave radiation issues in both military and civil fields. The desirable EWAMs feature strong absorption intensity, broad bandwidth, lightweight, thin thicknesses as well as other exceptional properties such as oxygen resistance, wear resistance, high-temperature resistance and high strength. In these regards, carbon-based materials, including carbon nanostructures and carbonaceous composites have become the significant participants of EWAMs, standing out for their unique structures and properties compared with the other absorption materials. In this review, we summarized the recent inspiring achievements in carbon-based EWAMs involving different dimensional (0D, 1D, 2D and 3D) carbon nanostructures and various types of carbonaceous composites (binary dielectric-carbon composite, binary magnetic-carbon composite and heterogeneous composite). Firstly, the influential factors affecting the electromagnetic microwave absorption (EWA) performances involving conductivity $\sigma $, permittivity $\varepsilon $and permeability $ \mu $ were discussed based on the EWA mechanisms. Secondly, the representative reports and corresponding mechanisms about improving the EWA performance of carbon-based EWAMs were highlighted and analyzed in detail such as self-modification and composite structure construction. Finally, the current modification strategies and research prospects of carbon-based EWAMs were summarized and outlined.
The synthesis of iron-nitrogen sites embedded in electrospun carbon nanofibers with superior ORR activity in alkaline and acidic media
XU Xiang-xiang, ZHANG Nian-chao, WANG Jun-ying, WANG Jun-zhong
, doi: 10.1016/S1872-5805(22)60649-8
摘要(40) HTML(27) PDF(1)
摘要:
Metal-nitrogen carbon catalysts have received great attention in the field of gas-involving electrocatalysis due to their high activity, large specific surface area and efficient gas diffusion pathways. Carbon nanofibers embedded with iron-nitrogen active sites were synthesized through an electrospinning approach followed by high-temperature treatment. We found that the introduction of g-C3N4 can enhance the anchoring of iron-nitrogen sites in the nanofiber, thus avoiding the formation of inorganic nanoparticles during high-temperature annealing. Compare with Fe3C/CNFs prepared without g-C3N4, Fe/CNFs showed an outstanding 4e oxygen reduction reaction (ORR) activity in both alkaline and acidic media. Furthermore, as air electrodes in Zn-air batteries, Fe/CNFs catalyst exhibit excellent performance with an open-circuit voltage of up to 1.49 V, a power density of 146 mW cm−2 and a specific capacity of 703 mAh gZn−1.This work proposes an effective strategy to prepare metal-nitrogen-carbon catalysts for energy-related electrocatalytic applications. Metal-nitrogen carbon catalysts have received great attention in the field of gas-involving electrocatalysis due to their high activity, large specific surface area and efficient gas diffusion pathways. Carbon nanofibers embedded with iron-nitrogen active sites were synthesized through an electrospinning approach followed by high-temperature treatment. We found that the introduction of g-C3N4 can enhance the anchoring of iron-nitrogen sites in the nanofiber, thus avoiding the formation of inorganic nanoparticles during high-temperature annealing. Compare with Fe3C/CNFs prepared without g-C3N4, Fe/CNFs showed an outstanding 4e oxygen reduction reaction (ORR) activity in both alkaline and acidic media. Furthermore, as air electrodes in Zn-air batteries, Fe/CNFs catalyst exhibit excellent performance with an open-circuit voltage of up to 1.49 V, a power density of 146 mW cm−2 and a specific capacity of 703 mAh gZn−1.This work proposes an effective strategy to prepare metal-nitrogen-carbon catalysts for energy-related electrocatalytic applications.
Wet-composition-induced amorphous adhesion toward a high interfacial shear strength between carbon fiber and polyetherketoneketone
ZHANG Feng, LI Bo-lan, JIAO Meng-xiao, LI Yan-bo, WANG Xin, YANG Yu, YANG Yu-qiu, ZHANG Xiao-hua
, doi: 10.1016/S1872-5805(22)60646-2
摘要(92) HTML(63) PDF(16)
摘要:
Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is the key factor to affect the mechanical performances of their composites, and thus it is very critical to impregnate PEKK into CF bundles as efficiently as possible. Here we report that owing to the high dissolubility, PEKK can be introduced onto CF surfaces via a wet strategy. The excellent wettability of PEKK guarantees a full covering and tight binding on CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. Furthermore, the interior of CF bundles can be completely and uniformly filled with PEKK by the solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS can reach 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the amorphous PEKK confined in the limited spacing between CFs. Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is the key factor to affect the mechanical performances of their composites, and thus it is very critical to impregnate PEKK into CF bundles as efficiently as possible. Here we report that owing to the high dissolubility, PEKK can be introduced onto CF surfaces via a wet strategy. The excellent wettability of PEKK guarantees a full covering and tight binding on CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. Furthermore, the interior of CF bundles can be completely and uniformly filled with PEKK by the solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS can reach 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the amorphous PEKK confined in the limited spacing between CFs.
3D hierarchical Ni/NiO@carbon nanosheets on graphene sheets with high capacitance contribution for lithium-ion storage
JIANG Shang, MAO Miao-miao, PANG Ming-jun, YANG Hui, WANG Run-wei, LI Ning, PAN Qi-liang, PANG Min, ZHAO Jian-guo
, doi: 10.1016/S1872-5805(22)60647-4
摘要(90) HTML(41) PDF(9)
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In the paper, Ni/NiO nanoparticles coated with a conductive carbon layer were synthesized by hydrothermal method. They were subjected to mild gradient calcination in argon, followed by partial oxidation in oxygen. Unique 3D consecutive electron conductive network as well as synergetic effect of Ni, NiO, carbon layer and graphene sheets can effectively alleviate a large volume expansion, which can restrain the electrode crushing and aggregation, and improve the conductivity. Moreover, Ni nanoparticles can reversibly decompose Li2O during delithiation procedure, which remarkably increases the reversible capacity of Ni/NiO@C/GN anodes. Thanks to these advantages, the Ni/NiO@C/GN hybrid material has better lithium-ion storage performance than Ni/NiO/C. Compared with the initial cycle (711.6 mA h g−1), the reversible capacity of 772.1 mA h g−1 can be maintained after 300 repetitions. The property assessment enables Ni/NiO@C/GN materials to be used in the next generation of large-capacity, high-rate, stable and environmentally friendly lithium-ion batteries. In the paper, Ni/NiO nanoparticles coated with a conductive carbon layer were synthesized by hydrothermal method. They were subjected to mild gradient calcination in argon, followed by partial oxidation in oxygen. Unique 3D consecutive electron conductive network as well as synergetic effect of Ni, NiO, carbon layer and graphene sheets can effectively alleviate a large volume expansion, which can restrain the electrode crushing and aggregation, and improve the conductivity. Moreover, Ni nanoparticles can reversibly decompose Li2O during delithiation procedure, which remarkably increases the reversible capacity of Ni/NiO@C/GN anodes. Thanks to these advantages, the Ni/NiO@C/GN hybrid material has better lithium-ion storage performance than Ni/NiO/C. Compared with the initial cycle (711.6 mA h g−1), the reversible capacity of 772.1 mA h g−1 can be maintained after 300 repetitions. The property assessment enables Ni/NiO@C/GN materials to be used in the next generation of large-capacity, high-rate, stable and environmentally friendly lithium-ion batteries.
基于天然三维多孔电极电化学氧化碳点制备及其钠电应用
李瑞林, 赵宗彬, 冷昌宇, 李勇, 艾李申, 孙洋, 王旭珍, 邱介山
, doi: 10.1016/S1872-5805(22)60644-9
摘要(37) HTML(36) PDF(5)
摘要:
碳点(CDs)是一种新兴的碳纳米材料,由于其高比表面积、良好的分散性、丰富的表面官能团、低生物毒性和光致发光特性而受到了研究者的广泛关注,然而,低成本、大规模和绿色合成CDs仍然面临挑战。本工作基于生物质玉米芯特殊的天然孔隙结构,经过直接碳化制备具有定向、贯通微纳米孔道的多孔三维电极材料,内外表面同时发生电化学氧化高效制备CDs,1 A恒电流下,每克电极材料制备CDs速率达到了79.83 mg h−1 ,将制备得到的CDs与氧化石墨烯(GO)水热复合得到复合气凝胶CDs/rGO材料,经过热处理后应用于钠离子电池,在1 A g−1下循环1000圈仍保持263.3 mAh g−1的容量。从生物质玉米芯出发简单高效制备碳点,为CDs的大规模绿色制备和应用提供了新的途径和思路。 碳点(CDs)是一种新兴的碳纳米材料,由于其高比表面积、良好的分散性、丰富的表面官能团、低生物毒性和光致发光特性而受到了研究者的广泛关注,然而,低成本、大规模和绿色合成CDs仍然面临挑战。本工作基于生物质玉米芯特殊的天然孔隙结构,经过直接碳化制备具有定向、贯通微纳米孔道的多孔三维电极材料,内外表面同时发生电化学氧化高效制备CDs,1 A恒电流下,每克电极材料制备CDs速率达到了79.83 mg h−1 ,将制备得到的CDs与氧化石墨烯(GO)水热复合得到复合气凝胶CDs/rGO材料,经过热处理后应用于钠离子电池,在1 A g−1下循环1000圈仍保持263.3 mAh g−1的容量。从生物质玉米芯出发简单高效制备碳点,为CDs的大规模绿色制备和应用提供了新的途径和思路。
Synergistic Enhancement of Toughness and Viscosity of Carbon Nanotubes/Polyether Imide/Polyether Ether Ketone Nanocomposites
SONG Jiu-peng, ZHAO Yan, LI Xue-kuan, XIONG Shu, LI Shuang, WANG Kai
, doi: 10.1016/S1872-5805(22)60643-7
摘要(73) HTML(51) PDF(6)
摘要:
Polyether ether ketone (PEEK) has favorable mechanical properties. However, its high melt viscosity limits its applications because it is hard to process. In this study, PEEK nanocomposites modified with carbon nanotubes (CNTs) and polyether imide (PEI) were prepared using a direct wet powder blending method. The melt viscosity of the nanocomposites decreased by approximately 50%. Under optimal conditions, the addition of CNTs and PEI resulted in a synergistic increase in the toughness of the nanocomposites. The elongation at break increased by 129%, and the fracture energy increased by 97%. The uniformly dispersed CNTs/PEI powder reduces the processing difficulty of PEEK nanocomposites without affecting the heat resistance. The nanocomposites prepared by this method have lower melt viscosity. This improvement of the properties of PEEK would facilitate its use in the preparation of thermoplastic composites by powder impregnation or laser sintering technology. Polyether ether ketone (PEEK) has favorable mechanical properties. However, its high melt viscosity limits its applications because it is hard to process. In this study, PEEK nanocomposites modified with carbon nanotubes (CNTs) and polyether imide (PEI) were prepared using a direct wet powder blending method. The melt viscosity of the nanocomposites decreased by approximately 50%. Under optimal conditions, the addition of CNTs and PEI resulted in a synergistic increase in the toughness of the nanocomposites. The elongation at break increased by 129%, and the fracture energy increased by 97%. The uniformly dispersed CNTs/PEI powder reduces the processing difficulty of PEEK nanocomposites without affecting the heat resistance. The nanocomposites prepared by this method have lower melt viscosity. This improvement of the properties of PEEK would facilitate its use in the preparation of thermoplastic composites by powder impregnation or laser sintering technology.
碳纳米管复合纤维素水凝胶的界面光热净水性能研究
王雪, 孙洋, 赵冠宇, 王旭珍, 邱介山
, doi: 10.1016/S1872-5805(22)60621-8
摘要(218) HTML(100) PDF(43)
摘要:
基于低温溶剂法从大宗农林废弃物玉米芯中提取的纤维素,耦合具有优异吸光性能的碳纳米管(CNTs),构筑复合纤维素水凝胶(CNTs-CH),利用纤维素凝胶的高保水性、可降解性,以及碳纳米管的高效光热转换能力、优良的力学性能和生物相容性,将其用于太阳能驱动界面水蒸发净化领域。考察了吸光材料CNTs的不同添加量对CNTs-CH复合水凝胶的太阳能吸收率、机械性能及界面光热水蒸发效率的影响。最优条件下,CNTs添加量仅需0.2 wt.%,此CNTs-CH复合纤维素水凝胶的平均蒸发速率可达到~1.52 kg m−2 h−1,太阳能-蒸汽转换效率约92%;在海水中连续蒸发8 h,蒸发速率可保持在1.37 kg m−2 h−1左右,且无积盐现象,净化水质远高于WHO和EPA对饮用水的标准,说明CNTs-CH抗盐性能较强。此外,CNTs-CH水凝胶在强酸/碱性水溶液体系、染料废水和重金属离子污染水体中的蒸发速率可维持在1.30-1.40 kg m−2 h−1,太阳能-蒸汽效率可达到80-86%,对污染物及盐分截留率高达99.9%,蒸发效果稳定,说明CNTs-CH光热蒸发器在海水淡化和工业废水净化回用领域有广阔的应用前景。 基于低温溶剂法从大宗农林废弃物玉米芯中提取的纤维素,耦合具有优异吸光性能的碳纳米管(CNTs),构筑复合纤维素水凝胶(CNTs-CH),利用纤维素凝胶的高保水性、可降解性,以及碳纳米管的高效光热转换能力、优良的力学性能和生物相容性,将其用于太阳能驱动界面水蒸发净化领域。考察了吸光材料CNTs的不同添加量对CNTs-CH复合水凝胶的太阳能吸收率、机械性能及界面光热水蒸发效率的影响。最优条件下,CNTs添加量仅需0.2 wt.%,此CNTs-CH复合纤维素水凝胶的平均蒸发速率可达到~1.52 kg m−2 h−1,太阳能-蒸汽转换效率约92%;在海水中连续蒸发8 h,蒸发速率可保持在1.37 kg m−2 h−1左右,且无积盐现象,净化水质远高于WHO和EPA对饮用水的标准,说明CNTs-CH抗盐性能较强。此外,CNTs-CH水凝胶在强酸/碱性水溶液体系、染料废水和重金属离子污染水体中的蒸发速率可维持在1.30-1.40 kg m−2 h−1,太阳能-蒸汽效率可达到80-86%,对污染物及盐分截留率高达99.9%,蒸发效果稳定,说明CNTs-CH光热蒸发器在海水淡化和工业废水净化回用领域有广阔的应用前景。
Nitrogen doped hollow-shaped porous carbon fiber derived from polyacrylonitrile for Li-S batteries
NIU Jing-yi, JING De-qi, ZHANG Xing-hua, SU Wei-guo, ZHANG Shou-chun
, doi: 10.1016/S1872-5805(22)60615-2
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摘要:
Hollow-shaped porous carbon fiber for Li-S batteries electrodes is prepared by KOH activation using polyacrylonitrile (PAN) as the precursor. The obtained porous carbon fiber has a high specific surface area of 2491 m2·g−1 and a large pore volume of 1.22 cm3·g−1. And it exhibits an initial specific capacity of 330 mAh·g−1 at current density of 1 C. To further improve electrochemical performance, the fiber precursor is modified using hydrazine hydrate to prepare nitrogen doped hollow-shaped porous carbon fiber. The modified fiber shows a specific surface area of 1690 m2·g−1, a pore volume of 0.84 cm3·g−1 and a high nitrogen content of 8.81 at%. Since nitrogen doping can increase the polarity and adsorption capacity, the initial specific capacity of the nitrogen doped porous carbon fiber can be increased to 420 mAh·g−1 at current density of 1 C. Hollow-shaped porous carbon fiber for Li-S batteries electrodes is prepared by KOH activation using polyacrylonitrile (PAN) as the precursor. The obtained porous carbon fiber has a high specific surface area of 2491 m2·g−1 and a large pore volume of 1.22 cm3·g−1. And it exhibits an initial specific capacity of 330 mAh·g−1 at current density of 1 C. To further improve electrochemical performance, the fiber precursor is modified using hydrazine hydrate to prepare nitrogen doped hollow-shaped porous carbon fiber. The modified fiber shows a specific surface area of 1690 m2·g−1, a pore volume of 0.84 cm3·g−1 and a high nitrogen content of 8.81 at%. Since nitrogen doping can increase the polarity and adsorption capacity, the initial specific capacity of the nitrogen doped porous carbon fiber can be increased to 420 mAh·g−1 at current density of 1 C.
Co/N-doped carbon catalyst derived from metal-organic framework (ZIF-8@ZIF-67) for efficient oxygen reduction reaction (ORR)
ZHANG Ya-ting, LI Si-yi, ZHANG Na-na, LIN Gang, WANG Rui-qi, YANG Meng-nan, LI Ke-ke
, doi: 10.1016/S1872-5805(22)60609-7
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摘要:
Carbon-based oxygen reduction reaction (ORR) catalysts are considered a potential substitution for the expensive platinum-based ORR catalysts in the aspect of energy conversion. Recently, metal and nitrogen codoped carbon materials (M-N-C) formed by transition metals and nitrogen-doped carbon materials have attracted much attention from researchers due to their low cost and excellent activity. Herein, a cobalt- and nitrogen-codoped porous carbon material (Co-N@CNT-C800) is prepared via a simple one-step pyrolysis method by well-designed carambola-shaped MOFs (ZIF-8@ZIF-67). The obtained Co-N@CNT-C800 consists of many carbon nanotubes (CNTs) with substantial Co doping and N doping. A large surface area (428 m2·g−1) and a favorable three-dimensional structure are also observed. The obtained Co-N@CNT-C800 exhibits excellent performance in half-wave potential and limited current density in alkaline media with a value of 0.841 V and 5.07 mA·cm−2, respectively. In addition, Co-N@CNT-C800 also shows excellent electrochemical stability and methanol tolerance compared with commercial Pt/C materials. The proposed strategy inspires a effective way to fabricate low cost and high activity electrocatalysts used for energy conversion. Carbon-based oxygen reduction reaction (ORR) catalysts are considered a potential substitution for the expensive platinum-based ORR catalysts in the aspect of energy conversion. Recently, metal and nitrogen codoped carbon materials (M-N-C) formed by transition metals and nitrogen-doped carbon materials have attracted much attention from researchers due to their low cost and excellent activity. Herein, a cobalt- and nitrogen-codoped porous carbon material (Co-N@CNT-C800) is prepared via a simple one-step pyrolysis method by well-designed carambola-shaped MOFs (ZIF-8@ZIF-67). The obtained Co-N@CNT-C800 consists of many carbon nanotubes (CNTs) with substantial Co doping and N doping. A large surface area (428 m2·g−1) and a favorable three-dimensional structure are also observed. The obtained Co-N@CNT-C800 exhibits excellent performance in half-wave potential and limited current density in alkaline media with a value of 0.841 V and 5.07 mA·cm−2, respectively. In addition, Co-N@CNT-C800 also shows excellent electrochemical stability and methanol tolerance compared with commercial Pt/C materials. The proposed strategy inspires a effective way to fabricate low cost and high activity electrocatalysts used for energy conversion.
An Innovative and Efficient Preparation of Mesocarbon Microbeads by The Delayed Capillary Breakup Method and Their Electrochemical Performance
DONG Si-lin, YANG Jian-xiao, CHANG Sheng-kai, SHI Kui, LIU Yue, ZOU Jia-ling, LI Jun
, doi: 10.1016/S1872-5805(22)60606-1
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摘要:
An innovative and efficient preparation method of mesocarbon microbeads (MCMBs) was developed based on the dripping behavior and rheological theory of pitch during the melt-spinning process, named as the delayed capillary breakup (DCB) method. In this work, the MCMBs were prepared by the DCB method with different receiving solvents (water or tetrahydrofuran (THF)), and their microstructure evolutions were compared systematically. Moreover, the MCMBs were further activated with KOH at 750 °C or graphitized at 2800 °C to prepare the A-MCMBs or G-MCMBs, and their electrochemical performance as electrode materials for electronic double layer capacitors (EDLC) or lithium-ion batteries (LIB) was investigated, respectively. The results showed that both MCMB-W prepared from water and MCMB-T prepared from THF had great spherical structure with the size of 1~2 μm. In addition, A-MCMB-T had a high specific surface area (1391 m2 g−1), micropore volume (0.55 cm3 g−1) and mesopore volume (0.24 cm3 g−1), exhibiting 30% higher specific capacitance than the original material, and its capacitance retention was also significantly improved when it was used as an electrode material for EDLC. Moreover, G-MCMB-T had high graphitization degree (0.895) and orderly lamellar structure, which demonstrated high specific capacity of 353.5 mAh g−1 after 100 cycles at 100 mA g−1 when it was used as an electrode material for LIB. Therefore, this work proposed and verified a new preparation method of MCMBs, which could provide a strategy for designing and developing traditional energy storage materials. An innovative and efficient preparation method of mesocarbon microbeads (MCMBs) was developed based on the dripping behavior and rheological theory of pitch during the melt-spinning process, named as the delayed capillary breakup (DCB) method. In this work, the MCMBs were prepared by the DCB method with different receiving solvents (water or tetrahydrofuran (THF)), and their microstructure evolutions were compared systematically. Moreover, the MCMBs were further activated with KOH at 750 °C or graphitized at 2800 °C to prepare the A-MCMBs or G-MCMBs, and their electrochemical performance as electrode materials for electronic double layer capacitors (EDLC) or lithium-ion batteries (LIB) was investigated, respectively. The results showed that both MCMB-W prepared from water and MCMB-T prepared from THF had great spherical structure with the size of 1~2 μm. In addition, A-MCMB-T had a high specific surface area (1391 m2 g−1), micropore volume (0.55 cm3 g−1) and mesopore volume (0.24 cm3 g−1), exhibiting 30% higher specific capacitance than the original material, and its capacitance retention was also significantly improved when it was used as an electrode material for EDLC. Moreover, G-MCMB-T had high graphitization degree (0.895) and orderly lamellar structure, which demonstrated high specific capacity of 353.5 mAh g−1 after 100 cycles at 100 mA g−1 when it was used as an electrode material for LIB. Therefore, this work proposed and verified a new preparation method of MCMBs, which could provide a strategy for designing and developing traditional energy storage materials.
Oxidation reaction mechanism and kinetics of ethylene tar for preparation of carbonaceous precursor
GUO Tian-rui, CHEN Rong-qi, GAO Wei, WANG Yan-li, ZHAN Liang
, doi: 10.1016/S1872-5805(22)60597-3
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摘要:
To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. The oxidation process of ethylene tar was divided into three stages (350-550 K, 550-700 K and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of evolved gases at different stages were further analyzed online by mass spectrometry and infrared technology. Then, based on the thermogravimetric curve of ethylene tar at different reaction temperatures, the whole reaction process was divided into four parts to perform kinetics simulation calculation. With the help of the iso-conversional method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, the optimal reaction kinetics model for expressing oxidation process of ethylene tar was determined. The results show that: (1) In the oxidation process, the side chains of aromatic compounds firstly react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals to aromatic rings. After that, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reaction to form larger molecular. (2) The fourth-order of reaction model is adopted to describe the first three parts of the oxidation process, and the activation energies are 47.330 kJ·mol−1, 18.689 kJ·mol−1 and 9.004 kJ·mol−1 respectively. The three-dimensional diffusion model is applied to the fourth part of the oxidation process, and the activation energy is 88.369 kJ·mol−1. To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. The oxidation process of ethylene tar was divided into three stages (350-550 K, 550-700 K and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of evolved gases at different stages were further analyzed online by mass spectrometry and infrared technology. Then, based on the thermogravimetric curve of ethylene tar at different reaction temperatures, the whole reaction process was divided into four parts to perform kinetics simulation calculation. With the help of the iso-conversional method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, the optimal reaction kinetics model for expressing oxidation process of ethylene tar was determined. The results show that: (1) In the oxidation process, the side chains of aromatic compounds firstly react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals to aromatic rings. After that, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reaction to form larger molecular. (2) The fourth-order of reaction model is adopted to describe the first three parts of the oxidation process, and the activation energies are 47.330 kJ·mol−1, 18.689 kJ·mol−1 and 9.004 kJ·mol−1 respectively. The three-dimensional diffusion model is applied to the fourth part of the oxidation process, and the activation energy is 88.369 kJ·mol−1.
Se encapsulated into honeycomb 3D porous carbon with Se-C bonds as superb performance cathodes for Li-Se Batteries
XIA Zhi-gang, ZHANG Jing-jing, FAN Mei-qiang, LV Chun-ju, CHEN Zhi, LI Chao
, doi: 10.1016/S1872-5805(22)60596-1
摘要(99) HTML(59) PDF(14)
摘要:
Li-Se Batteries has been considered as promising lithium-ion batteries due to their super volumetric energy density and high electrical conductivity of Se. However, the development of Li-Se batteries application is impeded by the boring volume expansion and polyselenide dissolution of electrodes during cycling, as well as the low selenium loading. A feasible and effective approach to settle these three issues is to keep selenium into a carbon host with sufficient pore volume and simultaneously enhance the interfacial interaction between selenium and carbon. A novel cathode material of Se encapsulated into honeycomb 3D porous carbon (HPC@Se) with Se-C bonds for Li-Se Batteries is synthesized by impregnating Se into the tartrate salt derived honeycomb 3D porous carbon. The pore volume of the obtained honeycomb 3D porous carbon is up to 1.794 cm3 g−1, which allows 65%wt selenium to be uniformly encapsulated. Moreover, the strong chemical bonds between selenium and carbon are beneficial for stabilizing selenium, thus further relieving its huge volume expansion and polyselenide dissolution as well as promote the charge transfer during cycling. As expected, HPC@Se cathode presents fantastic cyclability and rate performance. After 200 cycles, its specific capacity remained at 561 mA h g−1 (83% of the theoretical specific capacity) at 0.2 C. And the capacity recession is just 0.058 percentage each cycle. Besides, HPC@Se cathode can also demonstrate a considerable capacity of 472.8 mA h g−1 under the higher current density of 5 C. Li-Se Batteries has been considered as promising lithium-ion batteries due to their super volumetric energy density and high electrical conductivity of Se. However, the development of Li-Se batteries application is impeded by the boring volume expansion and polyselenide dissolution of electrodes during cycling, as well as the low selenium loading. A feasible and effective approach to settle these three issues is to keep selenium into a carbon host with sufficient pore volume and simultaneously enhance the interfacial interaction between selenium and carbon. A novel cathode material of Se encapsulated into honeycomb 3D porous carbon (HPC@Se) with Se-C bonds for Li-Se Batteries is synthesized by impregnating Se into the tartrate salt derived honeycomb 3D porous carbon. The pore volume of the obtained honeycomb 3D porous carbon is up to 1.794 cm3 g−1, which allows 65%wt selenium to be uniformly encapsulated. Moreover, the strong chemical bonds between selenium and carbon are beneficial for stabilizing selenium, thus further relieving its huge volume expansion and polyselenide dissolution as well as promote the charge transfer during cycling. As expected, HPC@Se cathode presents fantastic cyclability and rate performance. After 200 cycles, its specific capacity remained at 561 mA h g−1 (83% of the theoretical specific capacity) at 0.2 C. And the capacity recession is just 0.058 percentage each cycle. Besides, HPC@Se cathode can also demonstrate a considerable capacity of 472.8 mA h g−1 under the higher current density of 5 C.
KOH Treated Mesocarbon Microbeads as High Rate Anode for Potassium-Ion Batteries
XIAO Nan, GUO Hong-da, XIAO Jian, WEI Yi-bo, MA Xiao-qing, ZHANG Xiao-yu, QIU Jie-shan
, doi: 10.1016/S1872-5805(21)60059-8
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摘要:
Graphite is one of the most promising anode materials for potassium-ion batteries (PIBs) due to its low cost and stable discharge plateau. However, its poor rate performance still needs to be improved. Herein, a novel graphitic anode was designed from commercial mesocarbon microbeads (MCMB) by KOH treatment. Through limited oxidation and slight intercalation, an expanded layer with enlarged interlayer spacing formed on the surface of MCMB, by which the K+ diffusion rate was significantly improved. When served as the PIB anode, this modified MCMB delivered a high plateau capacity below 0.25 V (271 mAh g−1), superior rate capability (160 mAh g−1 at 1.0 A g−1), excellent cycling stability (about 184 mAh g−1 after 100 cycles at 0.1 A g−1), and high initial coulombic efficiency with carboxymethyl cellulose as binder (79.2%). This work provides a facile strategy to prepare graphitic materials with superior potassium storage property. Graphite is one of the most promising anode materials for potassium-ion batteries (PIBs) due to its low cost and stable discharge plateau. However, its poor rate performance still needs to be improved. Herein, a novel graphitic anode was designed from commercial mesocarbon microbeads (MCMB) by KOH treatment. Through limited oxidation and slight intercalation, an expanded layer with enlarged interlayer spacing formed on the surface of MCMB, by which the K+ diffusion rate was significantly improved. When served as the PIB anode, this modified MCMB delivered a high plateau capacity below 0.25 V (271 mAh g−1), superior rate capability (160 mAh g−1 at 1.0 A g−1), excellent cycling stability (about 184 mAh g−1 after 100 cycles at 0.1 A g−1), and high initial coulombic efficiency with carboxymethyl cellulose as binder (79.2%). This work provides a facile strategy to prepare graphitic materials with superior potassium storage property.