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doi: 10.1016/S1872-5805(24)60841-3
摘要:
The development of advanced aircrafts relies on high performance thermal-structural materials and composites of carbon/carbon (C/C) with ultrahigh-temperature ceramics are ideal candidates. However, traditional routes of compositing are either inefficient and expensive or lead to non-uniform distribution of ceramics in the matrix. Here, vacuum filtration of ZrB2 was successfully applied to introduce ZrB2-ZrC-SiC into C/C as a supplement for reactive melt infiltration ZrSi2, which contributed to the content increase and uniform distribution of the introduced ceramic phases. The mass and linear ablation rates of the composites were reduced by 68.9% and 29.7%, respectively, compared to those of C/C-ZrC-SiC composites prepared through reactive melt infiltration. The ablation performance was improved because of the volatilization of B2O3, taking a part of the heat away, and more uniformly distributed ZrO2 that could promote the formation of ZrO2-SiO2 continuous protective layer. This efficiently resisted the mechanical denudation and hindered the oxygen infiltration.
The development of advanced aircrafts relies on high performance thermal-structural materials and composites of carbon/carbon (C/C) with ultrahigh-temperature ceramics are ideal candidates. However, traditional routes of compositing are either inefficient and expensive or lead to non-uniform distribution of ceramics in the matrix. Here, vacuum filtration of ZrB2 was successfully applied to introduce ZrB2-ZrC-SiC into C/C as a supplement for reactive melt infiltration ZrSi2, which contributed to the content increase and uniform distribution of the introduced ceramic phases. The mass and linear ablation rates of the composites were reduced by 68.9% and 29.7%, respectively, compared to those of C/C-ZrC-SiC composites prepared through reactive melt infiltration. The ablation performance was improved because of the volatilization of B2O3, taking a part of the heat away, and more uniformly distributed ZrO2 that could promote the formation of ZrO2-SiO2 continuous protective layer. This efficiently resisted the mechanical denudation and hindered the oxygen infiltration.
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doi: 10.1016/S1872-5805(24)60845-0
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It is imperative to design the suitable anode materials of both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) with high-rate performance and ultralong cycling life. Herein, we fabricate a MoO2/MoS2 heterostructure that is homogeneously distributed in N,S-doped carbon nanofibers (MoO2/MoS2@NSC) by electrospinning technique and sulfuration engineering. The one-dimensional carbon fiber skeleton serves as a conductive frame to decrease the diffusion pathway of Li+/Na+. The doping of N/S heteroatoms in carbon fibers creates abundant active sites and significantly enhances ion diffusion kinetics. Moreover, the in situ formation of MoS2 nanosheets on the MoO2 phase bulk intensifies the heterointerface, and the construction of heterointerface between MoO2 and MoS2 enables the fast Li+/Na+ transport, which is crucial for achieving the high efficiency energy storage. Consequently, as the anode for LIBs, MoO2/MoS2@NSC delivers fantabulous cycle stability of 640 mAh g−1 upon 2000 cycles under 5.0 A g−1 with an ultralow average capacity drop rate of 0.002% per cycle and exceptional rate capability of 614 mAh g−1 at 10.0 A g−1. In SIBs, it still renders the significantly enhanced electrochemical performance (reversible capacity of 242 mAh g−1 under 2.0 A g−1 upon 2000 loops and 261 mAh g−1 under 5.0 A g−1). The current work exploits a novel interface manipulation strategy to rationally develop anode materials, achieving rapid Li+/Na+ storage kinetics and durable cycling performance.
It is imperative to design the suitable anode materials of both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) with high-rate performance and ultralong cycling life. Herein, we fabricate a MoO2/MoS2 heterostructure that is homogeneously distributed in N,S-doped carbon nanofibers (MoO2/MoS2@NSC) by electrospinning technique and sulfuration engineering. The one-dimensional carbon fiber skeleton serves as a conductive frame to decrease the diffusion pathway of Li+/Na+. The doping of N/S heteroatoms in carbon fibers creates abundant active sites and significantly enhances ion diffusion kinetics. Moreover, the in situ formation of MoS2 nanosheets on the MoO2 phase bulk intensifies the heterointerface, and the construction of heterointerface between MoO2 and MoS2 enables the fast Li+/Na+ transport, which is crucial for achieving the high efficiency energy storage. Consequently, as the anode for LIBs, MoO2/MoS2@NSC delivers fantabulous cycle stability of 640 mAh g−1 upon 2000 cycles under 5.0 A g−1 with an ultralow average capacity drop rate of 0.002% per cycle and exceptional rate capability of 614 mAh g−1 at 10.0 A g−1. In SIBs, it still renders the significantly enhanced electrochemical performance (reversible capacity of 242 mAh g−1 under 2.0 A g−1 upon 2000 loops and 261 mAh g−1 under 5.0 A g−1). The current work exploits a novel interface manipulation strategy to rationally develop anode materials, achieving rapid Li+/Na+ storage kinetics and durable cycling performance.
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doi: 10.1016/S1872-5805(24)60846-2
摘要:
Electrocatalytic oxygen reduction by a two-electron pathway enables the instantaneous synthesis of hydrogen peroxide, which is far superior to the conventional anthraquinone process. In recent years, the electrocatalytic synthesis of hydrogen peroxide using carbon electrodes has attracted more and more attention due to its excellent catalytic performance and superior stability. In this paper, the relationship between material modification, wettability adjustment and the rate of hydrogen peroxide synthesis, service life is considered together with the three-phase interface. The structure of carbon electrodes and the principle of electrocatalytic hydrogen peroxide synthesis are first introduced. Then, four main catalysts are reviewed, namely, monolithic carbon materials, metal-free catalysts, noble metal catalysts and non-precious metal catalysts. The effects of metal anode and electrolyte on the three-phase interface are described. Next, the relationship between carbon electrode wettability and the three-phase interface is described, pointing out that modification focusing on the improvement of the selectivity of the two-electron pathway can also impact electrode wettability. In addition, the relationship between the rational design of the components in the electrochemical system and the enhancement of the efficient of hydrogen peroxide synthesis at carbon electrodes is also discussed. Finally, we present our viewpoints on the current problems in the electrocatalytic synthesis of hydrogen peroxide at carbon electrodes and future research directions.
Electrocatalytic oxygen reduction by a two-electron pathway enables the instantaneous synthesis of hydrogen peroxide, which is far superior to the conventional anthraquinone process. In recent years, the electrocatalytic synthesis of hydrogen peroxide using carbon electrodes has attracted more and more attention due to its excellent catalytic performance and superior stability. In this paper, the relationship between material modification, wettability adjustment and the rate of hydrogen peroxide synthesis, service life is considered together with the three-phase interface. The structure of carbon electrodes and the principle of electrocatalytic hydrogen peroxide synthesis are first introduced. Then, four main catalysts are reviewed, namely, monolithic carbon materials, metal-free catalysts, noble metal catalysts and non-precious metal catalysts. The effects of metal anode and electrolyte on the three-phase interface are described. Next, the relationship between carbon electrode wettability and the three-phase interface is described, pointing out that modification focusing on the improvement of the selectivity of the two-electron pathway can also impact electrode wettability. In addition, the relationship between the rational design of the components in the electrochemical system and the enhancement of the efficient of hydrogen peroxide synthesis at carbon electrodes is also discussed. Finally, we present our viewpoints on the current problems in the electrocatalytic synthesis of hydrogen peroxide at carbon electrodes and future research directions.
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doi: 10.1016/S1872-5805(24)60838-3
摘要:
Lithium-sulfur (Li-S) batteries are among the most promising next-generation electrochemical energy-storage systems due to their exceptional theoretical specific capacity, inexpensive production cost and environmental friendliness. However, the poor conductivity of S and Li2S, severe polysulfides shuttling and sluggish redox kinetics of phase transformation greatly hinder the practical commercialization of Li-S batteries. Carbonaceous materials could potentially rescue Li-S batteries from this predicament by leveraging the inherently high specific surface area, excellent electrical conductivity, and structural diversity. However, non-polar carbon materials are unable to interact closely with highly polar polysulfides, resulting in a low sulfur utilization and serious shuttle effect. Due to the advantages of strong polarity and rich adsorption sites of transition metal oxides (TMOs), integrating TMOs with carbon-based materials (CM) is essential to enhance chemical adsorption and electrochemical reaction activity for lithium polysulfides (LiPSs). In this review, first, the working principles and main challenges in Li-S batteries are discussed followed by the recent research progress of ex-situ and in-situ synthesis strategies of TMOs-CM. Subsequently, the overall structural construction of TMOs-CM with different dimensionalities from 1D to 3D are reviewed. Moreover, the representative works and working mechanisms of modulation strategies including heterostructures design, vacancies engineering and facets manipulating are overviewed in detail. Finally, an outlook of TMOs-CM in Li-S batteries is proposed based on the review's conclusions.
Lithium-sulfur (Li-S) batteries are among the most promising next-generation electrochemical energy-storage systems due to their exceptional theoretical specific capacity, inexpensive production cost and environmental friendliness. However, the poor conductivity of S and Li2S, severe polysulfides shuttling and sluggish redox kinetics of phase transformation greatly hinder the practical commercialization of Li-S batteries. Carbonaceous materials could potentially rescue Li-S batteries from this predicament by leveraging the inherently high specific surface area, excellent electrical conductivity, and structural diversity. However, non-polar carbon materials are unable to interact closely with highly polar polysulfides, resulting in a low sulfur utilization and serious shuttle effect. Due to the advantages of strong polarity and rich adsorption sites of transition metal oxides (TMOs), integrating TMOs with carbon-based materials (CM) is essential to enhance chemical adsorption and electrochemical reaction activity for lithium polysulfides (LiPSs). In this review, first, the working principles and main challenges in Li-S batteries are discussed followed by the recent research progress of ex-situ and in-situ synthesis strategies of TMOs-CM. Subsequently, the overall structural construction of TMOs-CM with different dimensionalities from 1D to 3D are reviewed. Moreover, the representative works and working mechanisms of modulation strategies including heterostructures design, vacancies engineering and facets manipulating are overviewed in detail. Finally, an outlook of TMOs-CM in Li-S batteries is proposed based on the review's conclusions.
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doi: 10.1016/S1872-5805(24)60844-9
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The efficient electrocatalysts with low cost, high activity and good durability plays a crucial role in the application of direct formic acid fuel cells. Herein, Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCN) embedded in N-doped graphene (NG) with three-dimensional (3D) layered porous configuration by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Owing to the unique 3D interconnected layered porous configuration doped with nitrogen atoms, Pd/NHCN@NG catalyst with smaller Pd nanoparticle size shows large catalytic active surface area, superior electrocatalytic activity, high steady-state current density, strong ability to resist CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. By optimizing the HCN/GO ratio, it is found that when the HCN/GO mass ratio is 1∶1, Pd/NHCN@NG catalyst has the most outstanding performance in catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work has developed a superior carbon-based support material for electrocatalysts, which brings broad application prospects for the development of fuel cells.
The efficient electrocatalysts with low cost, high activity and good durability plays a crucial role in the application of direct formic acid fuel cells. Herein, Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCN) embedded in N-doped graphene (NG) with three-dimensional (3D) layered porous configuration by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Owing to the unique 3D interconnected layered porous configuration doped with nitrogen atoms, Pd/NHCN@NG catalyst with smaller Pd nanoparticle size shows large catalytic active surface area, superior electrocatalytic activity, high steady-state current density, strong ability to resist CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. By optimizing the HCN/GO ratio, it is found that when the HCN/GO mass ratio is 1∶1, Pd/NHCN@NG catalyst has the most outstanding performance in catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work has developed a superior carbon-based support material for electrocatalysts, which brings broad application prospects for the development of fuel cells.
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doi: 10.1016/S1872-5805(24)60835-8
摘要:
Graphene often tends to be horizontally oriented during processing owing to its two-dimensional layer structure with a high aspect ratio. As a consequence, thermal interface materials (TIM) composed of polymer and graphene often have elevated in-plane (IP) thermal conductivities (K), however, the restricted TP conductivity (K) renders them less favorable for practical implementations. This study presents the development of vertically aligned skeletons of high-quality polyimide/graphite nanosheets (PG) in order to enhance the TP K of polymer-based composites using a straightforward directional freezing technique. Notably, the graphene-based graphite nanosheets (GNs) are obtained by crushing from highly thermally conductive graphene film scraps. Water-soluble polyamic acid salt solution is used for direct dispersion of hydrophobic GNs fillers to achieve directional freezing. The polyimide, which facilitated the directional alignment of GNs, underwent graphitization and was subsequently transformed to graphite. Moreover, the introduction of GNs enhances the orderliness and density of the PG, thus further improving the strength and heat performance of its polydimethylsiloxane (PDMS) composite. The obtained PDMS/PG composite (PG: 21.1%, mass fraction) exhibits an impressive TP K of 14.56 W·m−1·K−1, 81 times that of pure PDMS. This facile polyimide-assisted graphene alignment method provides ideas for the widespread fabrication of anisotropic TIM and enables the reuse of graphene film scraps.
Graphene often tends to be horizontally oriented during processing owing to its two-dimensional layer structure with a high aspect ratio. As a consequence, thermal interface materials (TIM) composed of polymer and graphene often have elevated in-plane (IP) thermal conductivities (K), however, the restricted TP conductivity (K) renders them less favorable for practical implementations. This study presents the development of vertically aligned skeletons of high-quality polyimide/graphite nanosheets (PG) in order to enhance the TP K of polymer-based composites using a straightforward directional freezing technique. Notably, the graphene-based graphite nanosheets (GNs) are obtained by crushing from highly thermally conductive graphene film scraps. Water-soluble polyamic acid salt solution is used for direct dispersion of hydrophobic GNs fillers to achieve directional freezing. The polyimide, which facilitated the directional alignment of GNs, underwent graphitization and was subsequently transformed to graphite. Moreover, the introduction of GNs enhances the orderliness and density of the PG, thus further improving the strength and heat performance of its polydimethylsiloxane (PDMS) composite. The obtained PDMS/PG composite (PG: 21.1%, mass fraction) exhibits an impressive TP K of 14.56 W·m−1·K−1, 81 times that of pure PDMS. This facile polyimide-assisted graphene alignment method provides ideas for the widespread fabrication of anisotropic TIM and enables the reuse of graphene film scraps.
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doi: 10.1016/S1872-5805(24)60830-9
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A nascent two-dimensional (2D) carbon molecule called graphdiyne (GDY) has gained prominence recently and is expected to have supplications in the expulsion of contaminants from aqueous medium. GDY demonstrates superior conjugation, peculiar and tunable electronic properties, and exceptional chemical and thermal endurance because it is the framework of sp and sp2 hybridized carbon atoms that are combined to produce benzene rings and diacetylenic bonds in a two-dimensional symmetrical network. GDY’s molecular chemistry encompasses carbon-carbon triple bonds, along with its regular distribution of triangle pores in structure, which provides reaction sites and various reaction pathways. Here, GDY is considered to exhibits an adsorption phenomenon this can serve as an adsorbent, demonstrating excellent efficiency for the removal of oil, organic pollutants, dyes, and metals from contaminated water. There is limited evidence of GDY being used as an adsorbent in the literature review. This review's objective is to offer a modern perspective on the application of GDY as an adsorbent material.
A nascent two-dimensional (2D) carbon molecule called graphdiyne (GDY) has gained prominence recently and is expected to have supplications in the expulsion of contaminants from aqueous medium. GDY demonstrates superior conjugation, peculiar and tunable electronic properties, and exceptional chemical and thermal endurance because it is the framework of sp and sp2 hybridized carbon atoms that are combined to produce benzene rings and diacetylenic bonds in a two-dimensional symmetrical network. GDY’s molecular chemistry encompasses carbon-carbon triple bonds, along with its regular distribution of triangle pores in structure, which provides reaction sites and various reaction pathways. Here, GDY is considered to exhibits an adsorption phenomenon this can serve as an adsorbent, demonstrating excellent efficiency for the removal of oil, organic pollutants, dyes, and metals from contaminated water. There is limited evidence of GDY being used as an adsorbent in the literature review. This review's objective is to offer a modern perspective on the application of GDY as an adsorbent material.
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doi: 10.1016/S1872-5805(24)60842-5
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Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g−1 at 20 mA g−1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g−1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.
Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g−1 at 20 mA g−1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g−1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.
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doi: 10.1016/S1872-5805(24)60840-1
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通信技术在为人类的生活带来便利的同时,其产生的电磁辐射对社会安全、人体健康产生的危害也受到了社会各界的广泛关注,宽屏蔽范围、高吸收效率和高稳定性的电磁屏蔽材料逐渐成为研究热点。石墨烯是一种导电性高、比表面积大且可调控性高的轻质材料,可有效实现电磁衰减,保护精密电子设备和人体健康,在电磁屏蔽领域具有广阔的应用前景。本文从电磁屏蔽的基本原理与石墨烯基材料的结构特性出发,阐述了石墨烯及其衍生物的电磁屏蔽特点,总结了结构调控以及表面异质化、复合化策略在电磁屏蔽领域的应用。结构调控有利于提高石墨烯基材料对电磁波的吸收损耗和多重反射损耗;表面异质化和复合化策略有利于提高石墨烯基材料的界面极化和磁特性,从而加强对电磁波的吸收损耗和磁损耗。本文总结了石墨烯基电磁屏蔽材料的改性方法,旨在为开发新一代绿色、轻薄、高屏蔽带宽的电磁屏蔽材料提供启发,指明石墨烯基电磁屏蔽材料的未来发展方向。
通信技术在为人类的生活带来便利的同时,其产生的电磁辐射对社会安全、人体健康产生的危害也受到了社会各界的广泛关注,宽屏蔽范围、高吸收效率和高稳定性的电磁屏蔽材料逐渐成为研究热点。石墨烯是一种导电性高、比表面积大且可调控性高的轻质材料,可有效实现电磁衰减,保护精密电子设备和人体健康,在电磁屏蔽领域具有广阔的应用前景。本文从电磁屏蔽的基本原理与石墨烯基材料的结构特性出发,阐述了石墨烯及其衍生物的电磁屏蔽特点,总结了结构调控以及表面异质化、复合化策略在电磁屏蔽领域的应用。结构调控有利于提高石墨烯基材料对电磁波的吸收损耗和多重反射损耗;表面异质化和复合化策略有利于提高石墨烯基材料的界面极化和磁特性,从而加强对电磁波的吸收损耗和磁损耗。本文总结了石墨烯基电磁屏蔽材料的改性方法,旨在为开发新一代绿色、轻薄、高屏蔽带宽的电磁屏蔽材料提供启发,指明石墨烯基电磁屏蔽材料的未来发展方向。
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doi: 10.1016/S1872-5805(24)60827-9
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光热驱动的海水淡化技术被认为是最具潜力的解决全球淡水资源短缺难题的方法之一。其中,太阳能界面水蒸发(SVG)是海水淡化效率的核心过程,是保证光热海水淡化技术具有能量转换效率高、设备简单、成本效益高的关键。在所有高效SVG候选材料中,三维整体式碳基光热转换材料具有成本低、吸光效率高、结构可调性好、水蒸发速率高、无二次污染等优点。本综述首先简述了SVG 的基本原理,以此为依据介绍了高效 SVG 材料的工作机制和设计原则,最后系统归纳和概述了四种不同类型的三维整体式碳基光热转换材料的研究进展。所以本综述为未来三维整体式碳基光热转换材料的构建及其在SVG领域的应用研究提供理论基础和研究指导。
光热驱动的海水淡化技术被认为是最具潜力的解决全球淡水资源短缺难题的方法之一。其中,太阳能界面水蒸发(SVG)是海水淡化效率的核心过程,是保证光热海水淡化技术具有能量转换效率高、设备简单、成本效益高的关键。在所有高效SVG候选材料中,三维整体式碳基光热转换材料具有成本低、吸光效率高、结构可调性好、水蒸发速率高、无二次污染等优点。本综述首先简述了SVG 的基本原理,以此为依据介绍了高效 SVG 材料的工作机制和设计原则,最后系统归纳和概述了四种不同类型的三维整体式碳基光热转换材料的研究进展。所以本综述为未来三维整体式碳基光热转换材料的构建及其在SVG领域的应用研究提供理论基础和研究指导。
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doi: 10.1016/S1872-5805(24)60825-5
摘要:
锂硫电池因其高能量密度和低成本而成为最有发展前景的电化学储能器件之一。然而,多硫化物的“穿梭效应”、硫导电率低是锂硫电池商业化进程面临的主要挑战。本工作中,以九水合硝酸铁(Fe(NO)3·9H2O)为铁源,氟化铵(NH4F)为表面活性剂,通过简单的水热及煅烧处理制备了Fe2O3纳米棒修饰炭布(CC)的柔性Fe2O3/CC复合材料。其中,Fe2O3中介孔的存在有利于电解质的渗透和充放电过程中锂离子的传输和扩散,同时其密集阵列暴露出的丰富活性位点可以实现多硫化物的高效吸附和快速转化,降低多硫化物的穿梭效应。电化学分析显示:Fe2O3/CC正极在0.1 C(1 C=1672 mA g−1)的电流密度下具有1250 mAh g−1的高放电比容量,经过100圈循环后比容量保持在789 mAh g−1。在2 C的倍率下循环1000圈后仍能实现576 mAh g−1的放电比容量,容量保持率为70%,明显优于对比样品。上述结果表明,Fe2O3/CC能够很好地抑制多硫化物的穿梭,提高电池倍率性能和循环稳定性。
锂硫电池因其高能量密度和低成本而成为最有发展前景的电化学储能器件之一。然而,多硫化物的“穿梭效应”、硫导电率低是锂硫电池商业化进程面临的主要挑战。本工作中,以九水合硝酸铁(Fe(NO)3·9H2O)为铁源,氟化铵(NH4F)为表面活性剂,通过简单的水热及煅烧处理制备了Fe2O3纳米棒修饰炭布(CC)的柔性Fe2O3/CC复合材料。其中,Fe2O3中介孔的存在有利于电解质的渗透和充放电过程中锂离子的传输和扩散,同时其密集阵列暴露出的丰富活性位点可以实现多硫化物的高效吸附和快速转化,降低多硫化物的穿梭效应。电化学分析显示:Fe2O3/CC正极在0.1 C(1 C=1672 mA g−1)的电流密度下具有1250 mAh g−1的高放电比容量,经过100圈循环后比容量保持在789 mAh g−1。在2 C的倍率下循环1000圈后仍能实现576 mAh g−1的放电比容量,容量保持率为70%,明显优于对比样品。上述结果表明,Fe2O3/CC能够很好地抑制多硫化物的穿梭,提高电池倍率性能和循环稳定性。
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doi: 10.1016/S1872-5805(24)60823-1
摘要:
Micro-supercapacitors (MSCs) have garnered significant interest thanks to their high power density and excellent cyclic performance, offering a broad array of potential applications. However, preparing MSCs electrodes with extremely high areal capacitance and energy density remains a challenging pursuit. In this study, reduced graphene oxide aerogel (GA) and MoS2 were used as active materials, combined with 3D printing and surface modification methods, to construct MSCs electrodes with ultra-high area capacitance and energy density. Through 3D printing technology, we obtained electrodes with stable macro structure and GA crosslinked micropore structure. In addition, we used the solution method to load molybdenum disulfide nanosheets on the surface of the 3D printed electrode, further improving the electrochemical performance. The surface capacitance of the prepared electrode reached 3.99 F cm−2, the power density was 194 µW cm−2, and the energy density was 1997 mWh cm−2, attesting the excellent electrochemical performance and cycle stability. This work provides a simple and efficient method for preparing MSC electrodes with high areal capacitance and energy density, making them ideal for portable electronic devices. This research holds crucial innovative significance in the field of MSCs electrodes.
Micro-supercapacitors (MSCs) have garnered significant interest thanks to their high power density and excellent cyclic performance, offering a broad array of potential applications. However, preparing MSCs electrodes with extremely high areal capacitance and energy density remains a challenging pursuit. In this study, reduced graphene oxide aerogel (GA) and MoS2 were used as active materials, combined with 3D printing and surface modification methods, to construct MSCs electrodes with ultra-high area capacitance and energy density. Through 3D printing technology, we obtained electrodes with stable macro structure and GA crosslinked micropore structure. In addition, we used the solution method to load molybdenum disulfide nanosheets on the surface of the 3D printed electrode, further improving the electrochemical performance. The surface capacitance of the prepared electrode reached 3.99 F cm−2, the power density was 194 µW cm−2, and the energy density was 1997 mWh cm−2, attesting the excellent electrochemical performance and cycle stability. This work provides a simple and efficient method for preparing MSC electrodes with high areal capacitance and energy density, making them ideal for portable electronic devices. This research holds crucial innovative significance in the field of MSCs electrodes.
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doi: 10.1016/S1872-5805(24)60826-7
摘要:
The mesophase-pitch-based carbon fibers (MPCFs) were prepared by controlling the spinning temperature under a constant extrusion flowrate of pitch in an industrial equipment to investigate the influence of the spinning temperature on their microstructures, mechanical properties and thermal conductivities. Results show that the graphite layer of MPCFs shifts from a fine-and-folded radial-split structure to a large-and-flat radial-split structure and exhibits an improved perfection of graphite microcrystallites with increasing the spinning temperature from 309 to 320 °C. Meanwhile, the thermal conductivity and tensile strength of MPCFs increase, respectively, from 704 W·m−1·K−1 and 2.16 GPa at 309 °C to 1078 W·m−1·K−1 and 3.23 GPa at 320 °C. The lower viscosity and the weaker die-swell effect of mesophase pitch at the outlets of spinnerets at the higher spinning temperature contribute to the improved orientation of mesophase pitch molecules in the pitch fibers, which plays a positive role in improving the crystal size and orientation of MPCFs.
The mesophase-pitch-based carbon fibers (MPCFs) were prepared by controlling the spinning temperature under a constant extrusion flowrate of pitch in an industrial equipment to investigate the influence of the spinning temperature on their microstructures, mechanical properties and thermal conductivities. Results show that the graphite layer of MPCFs shifts from a fine-and-folded radial-split structure to a large-and-flat radial-split structure and exhibits an improved perfection of graphite microcrystallites with increasing the spinning temperature from 309 to 320 °C. Meanwhile, the thermal conductivity and tensile strength of MPCFs increase, respectively, from 704 W·m−1·K−1 and 2.16 GPa at 309 °C to 1078 W·m−1·K−1 and 3.23 GPa at 320 °C. The lower viscosity and the weaker die-swell effect of mesophase pitch at the outlets of spinnerets at the higher spinning temperature contribute to the improved orientation of mesophase pitch molecules in the pitch fibers, which plays a positive role in improving the crystal size and orientation of MPCFs.
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doi: 10.1016/S1872-5805(22)60597-3
摘要:
To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. Meanwhile, a high softening point pitch was produced to apply to the coating modification of the graphite anode in lithium-ion batteries. The oxidation process of ethylene tar was divided into 3 stages (350-550, 550-700 and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of the 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 calculations. 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 the oxidation process of ethylene tar was determined. The results show that: 1) In the oxidation process, the side chains of aromatic compounds react with oxygen to form alcohols and aldehydes first, leaving peroxy-radicals to aromatic rings. Subsequently, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reactions to form larger molecules. 2) The fourth-order reaction model is adopted to describe the first 3 parts of the oxidation process, and the activation energies are 47.330, 18.689 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. 3) After the coating modification, the capacity retention rate grows from 51.54% to 79.07% after 300 cycles.
To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. Meanwhile, a high softening point pitch was produced to apply to the coating modification of the graphite anode in lithium-ion batteries. The oxidation process of ethylene tar was divided into 3 stages (350-550, 550-700 and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of the 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 calculations. 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 the oxidation process of ethylene tar was determined. The results show that: 1) In the oxidation process, the side chains of aromatic compounds react with oxygen to form alcohols and aldehydes first, leaving peroxy-radicals to aromatic rings. Subsequently, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reactions to form larger molecules. 2) The fourth-order reaction model is adopted to describe the first 3 parts of the oxidation process, and the activation energies are 47.330, 18.689 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. 3) After the coating modification, the capacity retention rate grows from 51.54% to 79.07% after 300 cycles.
当前状态:
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doi: 10.1016/S1872-5805(24)60843-7
摘要:
随着新能源汽车迅速发展,动力锂离子电池应用越来越广泛,大量锂电池也迎来退役高峰期,废旧锂电池的回收综合利用已经引起世界各国高度关注。废旧锂电池石墨负极因其层状结构基本未变化,不需高温石墨化,只关注其内部杂质的去除。本文将废旧石墨负极热处理、超声分离和酸浸处理后,创新性地采用电化学处理将内部金属杂质深度去除。对比不同回收阶段的石墨,发现石墨中有机杂质的存在会严重影响各项电化学性能,微量Cu、Fe等无机杂质的存在对初始放电比容量影响不大,但会降低石墨的循环稳定性。最终回收的石墨内部主要金属杂质含量低于20 mg/kg,在0.1 C倍率下放电比容量达到358.7 mAh/g,循环150圈后容量保持率为95.85%。对比已报道的废旧石墨回收方法,此方法可深度去除石墨负极内部杂质,解决了目前酸碱用量大、除杂不彻底、能耗高等问题,回收再生石墨负极电化学性能较好,为废旧锂电池石墨负极提供了一条新的回收再生路径。
随着新能源汽车迅速发展,动力锂离子电池应用越来越广泛,大量锂电池也迎来退役高峰期,废旧锂电池的回收综合利用已经引起世界各国高度关注。废旧锂电池石墨负极因其层状结构基本未变化,不需高温石墨化,只关注其内部杂质的去除。本文将废旧石墨负极热处理、超声分离和酸浸处理后,创新性地采用电化学处理将内部金属杂质深度去除。对比不同回收阶段的石墨,发现石墨中有机杂质的存在会严重影响各项电化学性能,微量Cu、Fe等无机杂质的存在对初始放电比容量影响不大,但会降低石墨的循环稳定性。最终回收的石墨内部主要金属杂质含量低于20 mg/kg,在0.1 C倍率下放电比容量达到358.7 mAh/g,循环150圈后容量保持率为95.85%。对比已报道的废旧石墨回收方法,此方法可深度去除石墨负极内部杂质,解决了目前酸碱用量大、除杂不彻底、能耗高等问题,回收再生石墨负极电化学性能较好,为废旧锂电池石墨负极提供了一条新的回收再生路径。
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doi: 10.1016/S1872-5805(23)60741-3
摘要:
It is meaningful to find a toughener with a low dosage and effective improvement of interlaminar toughness in carbon fiber composites. In this paper, the toughening effect of phenolphthalein-based poly (ether sulfone) (PES-C) on E51/ DETDA epoxy and its carbon fiber composites (CFCs) was investigated. The SEM results showed that PES-C/epoxy blends formed sea-island phase and bicontinuous phase structure, which were associated with reaction-induced phase separation. After adding 15 phr PES-C, the glass transition temperature (Tg) of blends was increased by 51.5 °C. Meanwhile, the flexural strength, impact strength and fracture toughness of the blends were improved by 41.1%, 186.2% and 42.7%, respectively. These improvements could be attributed to the phase separation structure of the PES-C/epoxy system. Moreover, PES-C film was used to improve the mode-II fracture toughness (GIIC) of CFCs. GIIC value of the 7 μm PES-C film toughened laminate was improved by 80.3% than that of control laminate. The increase in GIIC could be attributed to cohesive failure and plastic deformation in the interleaving region.
It is meaningful to find a toughener with a low dosage and effective improvement of interlaminar toughness in carbon fiber composites. In this paper, the toughening effect of phenolphthalein-based poly (ether sulfone) (PES-C) on E51/ DETDA epoxy and its carbon fiber composites (CFCs) was investigated. The SEM results showed that PES-C/epoxy blends formed sea-island phase and bicontinuous phase structure, which were associated with reaction-induced phase separation. After adding 15 phr PES-C, the glass transition temperature (Tg) of blends was increased by 51.5 °C. Meanwhile, the flexural strength, impact strength and fracture toughness of the blends were improved by 41.1%, 186.2% and 42.7%, respectively. These improvements could be attributed to the phase separation structure of the PES-C/epoxy system. Moreover, PES-C film was used to improve the mode-II fracture toughness (GIIC) of CFCs. GIIC value of the 7 μm PES-C film toughened laminate was improved by 80.3% than that of control laminate. The increase in GIIC could be attributed to cohesive failure and plastic deformation in the interleaving region.
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doi: 10.1016/S1872-5805(22)60646-2
摘要:
Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. Therefore, it is of great importance 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 formation of amorphous PEKK confined in the limited spacing between CFs.
Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. Therefore, it is of great importance 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 formation of amorphous PEKK confined in the limited spacing between CFs.
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doi: 10.1016/S1872-5805(22)60643-7
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.
2024, 39(1): 1-16.
doi: 10.1016/S1872-5805(24)60831-0
摘要:
Electrocatalytic water splitting is a promising strategy to generate hydrogen using renewable energy under mild conditions. Carbon-based materials have attracted attention in electrocatalytic water splitting because of their distinctive features such as high specific area, high electron mobility and abundant natural resources. Hydrogen produced by industrial electrocatalytic water splitting in a large quantity requires electrocatalysis at a low overpotential at a large current density. Substantial efforts focused on fundamental research have been made, while much less attention has been paid to the high-current-density test. There are many distinct differences in electrocatalysis to split water using low and high current densities such as the bubble phenomenon, local environment around active sites, and stability. Recent research progress on carbon-based electrocatalysts for water splitting at low and high current densities is summarized, significant challenges and prospects for carbon-based electrocatalysts are discussed, and promising strategies are proposed.
Electrocatalytic water splitting is a promising strategy to generate hydrogen using renewable energy under mild conditions. Carbon-based materials have attracted attention in electrocatalytic water splitting because of their distinctive features such as high specific area, high electron mobility and abundant natural resources. Hydrogen produced by industrial electrocatalytic water splitting in a large quantity requires electrocatalysis at a low overpotential at a large current density. Substantial efforts focused on fundamental research have been made, while much less attention has been paid to the high-current-density test. There are many distinct differences in electrocatalysis to split water using low and high current densities such as the bubble phenomenon, local environment around active sites, and stability. Recent research progress on carbon-based electrocatalysts for water splitting at low and high current densities is summarized, significant challenges and prospects for carbon-based electrocatalysts are discussed, and promising strategies are proposed.
2024, 39(1): 17-41.
doi: 10.1016/S1872-5805(24)60833-4
摘要:
Electrocatalytic carbon dioxide (CO2) reduction is an important way to achieve carbon neutrality by converting CO2 into high-value-added chemicals using electric energy. Carbon-based materials are widely used in various electrochemical reactions, including electrocatalytic CO2 reduction, due to their low cost and high activity. In recent years, defect engineering has attracted wide attention by constructing asymmetric defect centers in the materials, which can optimize the physicochemical properties of the material and improve its electrocatalytic activity. This review summarizes the types, methods of formation and defect characterization techniques of defective carbon-based materials. The advantages of defect engineering and the advantages and disadvantages of various defect formation methods and characterization techniques are also evaluated. Finally, the challenges of using defective carbon-based materials in electrocatalytic CO2 reduction are investigated and opportunities for their use are discussed. It is believed that this review will provide suggestions and guidance for developing defective carbon-based materials for CO2 reduction.
Electrocatalytic carbon dioxide (CO2) reduction is an important way to achieve carbon neutrality by converting CO2 into high-value-added chemicals using electric energy. Carbon-based materials are widely used in various electrochemical reactions, including electrocatalytic CO2 reduction, due to their low cost and high activity. In recent years, defect engineering has attracted wide attention by constructing asymmetric defect centers in the materials, which can optimize the physicochemical properties of the material and improve its electrocatalytic activity. This review summarizes the types, methods of formation and defect characterization techniques of defective carbon-based materials. The advantages of defect engineering and the advantages and disadvantages of various defect formation methods and characterization techniques are also evaluated. Finally, the challenges of using defective carbon-based materials in electrocatalytic CO2 reduction are investigated and opportunities for their use are discussed. It is believed that this review will provide suggestions and guidance for developing defective carbon-based materials for CO2 reduction.
2024, 39(1): 42-63.
doi: 10.1016/S1872-5805(24)60836-X
摘要:
Electrocatalysis is a key component of many clean energy technologies that has the potential to store renewable electricity in chemical form. Currently, noble metal-based catalysts are most widely used for improving the conversion efficiency of reactants during the electrocatalytic process. However, drawbacks such as high cost and poor stability seriously hinder their large-scale use in this process and in sustainable energy devices. Carbon-based metal-free catalysts (CMFCs) have received growing attention due to their enormous potential for improving the catalytic performance. This review gives a concise comprehensive overview of recent developments in CMFCs for electrosynthesis. First, the fundamental catalytic mechanisms and design strategies of CMFCs are presented and discussed. Then, a brief overview of various electrosynthesis processes, including the synthesis of hydrogen peroxide, ammonia, chlorine, as well as various carbon- and nitrogen-based compounds is given. Finally, current challenges and prospects for CMFCs are highlighted.
Electrocatalysis is a key component of many clean energy technologies that has the potential to store renewable electricity in chemical form. Currently, noble metal-based catalysts are most widely used for improving the conversion efficiency of reactants during the electrocatalytic process. However, drawbacks such as high cost and poor stability seriously hinder their large-scale use in this process and in sustainable energy devices. Carbon-based metal-free catalysts (CMFCs) have received growing attention due to their enormous potential for improving the catalytic performance. This review gives a concise comprehensive overview of recent developments in CMFCs for electrosynthesis. First, the fundamental catalytic mechanisms and design strategies of CMFCs are presented and discussed. Then, a brief overview of various electrosynthesis processes, including the synthesis of hydrogen peroxide, ammonia, chlorine, as well as various carbon- and nitrogen-based compounds is given. Finally, current challenges and prospects for CMFCs are highlighted.
2024, 39(1): 64-77.
doi: 10.1016/S1872-5805(24)60829-2
摘要:
Producing organic electro-oxidation and hydrogen evolution reactions (HER) simultaneously in an electrolytic cell is an appealing method for generating valuable chemicals at the anode while also producing H2 at the cathode. Within this framework, the task of designing energy-saving electrocatalysts with high selectivity and stability is a considerable challenge. Carbon-based catalysts, along with their supports, have emerged as promising candidates due to their diverse sources, large specific surface area, high porosity and multidimensional characteristics. This review summarizes progress from 2012 to 2022, in the use of carbon-based catalysts and their supports for organic electrooxidation and HER. It delves into outer-sphere electrooxidation mechanisms involving molecule-mediated oxidation and oxidative radical coupling reactions, as well as inner-sphere electrooxidation mechanisms, encompassing both acidic and alkaline electrolytes. The review also explores prospective research directions within this domain, addressing various aspects such as the design of electrocatalytic materials, the study of the relationship between the structure and properties of electrocatalysts, as well as examining their potential industrial applications.
Producing organic electro-oxidation and hydrogen evolution reactions (HER) simultaneously in an electrolytic cell is an appealing method for generating valuable chemicals at the anode while also producing H2 at the cathode. Within this framework, the task of designing energy-saving electrocatalysts with high selectivity and stability is a considerable challenge. Carbon-based catalysts, along with their supports, have emerged as promising candidates due to their diverse sources, large specific surface area, high porosity and multidimensional characteristics. This review summarizes progress from 2012 to 2022, in the use of carbon-based catalysts and their supports for organic electrooxidation and HER. It delves into outer-sphere electrooxidation mechanisms involving molecule-mediated oxidation and oxidative radical coupling reactions, as well as inner-sphere electrooxidation mechanisms, encompassing both acidic and alkaline electrolytes. The review also explores prospective research directions within this domain, addressing various aspects such as the design of electrocatalytic materials, the study of the relationship between the structure and properties of electrocatalysts, as well as examining their potential industrial applications.
2024, 39(1): 78-99.
doi: 10.1016/S1872-5805(24)60828-0
摘要:
Because of the demand for clean and sustainable energy sources, nanocarbons, modified carbons and their composite materials derived from metal-organic frameworks (MOFs) are emerging as distinct catalysts for electrocatalytic energy conversion. These materials not only inherit the advantages of MOFs, like customizable dopants and structural diversity, but also effectively prevent the aggregation of nanoparticles of metals and metal oxides during pyrolysis. Consequently, they increase the electrocatalytic efficiency, improve electrical conductivity, and may play a pivotal role in green energy technologies such as fuel cells and metal-air batteries. This review first explores the carbonization mechanism of the MOF-derived carbon-based materials, and then considers 3 key aspects: intrinsic carbon defects, metal and non-metal atom doping, and the synthesis strategies for these materials. We also provide a comprehensive introduction to advanced characterization techniques to better understand the basic electrochemical catalysis processes, including mapping techniques for detecting localized active sites on electrocatalyst surfaces at the micro- to nano-scale and in-situ spectroscopy. Finally, we offer insights into future research concerning their use as electrocatalysts. Our primary objective is to provide a clearer perspective on the current status of MOF-derived carbon-based electrocatalysts and encourage the development of more efficient materials.
Because of the demand for clean and sustainable energy sources, nanocarbons, modified carbons and their composite materials derived from metal-organic frameworks (MOFs) are emerging as distinct catalysts for electrocatalytic energy conversion. These materials not only inherit the advantages of MOFs, like customizable dopants and structural diversity, but also effectively prevent the aggregation of nanoparticles of metals and metal oxides during pyrolysis. Consequently, they increase the electrocatalytic efficiency, improve electrical conductivity, and may play a pivotal role in green energy technologies such as fuel cells and metal-air batteries. This review first explores the carbonization mechanism of the MOF-derived carbon-based materials, and then considers 3 key aspects: intrinsic carbon defects, metal and non-metal atom doping, and the synthesis strategies for these materials. We also provide a comprehensive introduction to advanced characterization techniques to better understand the basic electrochemical catalysis processes, including mapping techniques for detecting localized active sites on electrocatalyst surfaces at the micro- to nano-scale and in-situ spectroscopy. Finally, we offer insights into future research concerning their use as electrocatalysts. Our primary objective is to provide a clearer perspective on the current status of MOF-derived carbon-based electrocatalysts and encourage the development of more efficient materials.
2024, 39(1): 100-130.
doi: 10.1016/S1872-5805(24)60839-5
摘要:
通过电化学方法来减少二氧化碳(CO2),同时生产燃料和高附加值化学品,是一种克服全球变暖问题的有效策略,对于缓解能源和环境的双重压力具有重要的现实意义。由于CO2稳定的分子结构,设计高选择性、高能效和低成本的电催化剂是关键。石墨烯及其衍生物因其独特且优异的物理、力学和电学性能,相对较低的成本,使其在CO2电还原方面具有竞争力。此外,石墨烯基材料的表面可以通过使用不同的方法进行改性,包括掺杂、缺陷工程、构建复合结构和包覆形状。首先,本文综述了电化学CO2还原的基本概念、评价标准,以及催化原理和过程。其次,简要介绍了石墨烯基催化剂的制备方法,并按照催化位点的类别,总结了石墨烯基催化剂近年来的研究进展。最后,对CO2电还原技术未来发展方向进行了探讨与展望。
2024, 39(1): 131-141.
doi: 10.1016/S1872-5805(24)60837-1
摘要:
Iron-chromium redox flow batteries (ICRFBs) use abundant and inexpensive chromium and iron as the active substances in the electrolyte and have great potential as a cost-effective and large-scale energy storage system. However, they are still plagued by several issues, such as the low electrochemical activity of Cr3+/Cr2+ and the occurrence of the undesired hydrogen evolution reaction (HER). We report the synthesis of amorphous bismuth (Bi) nanoparticles (NPs) immobilized on N-doped graphite felts (GFs) by a combined self-polymerization and wet-chemistry reduction strategy followed by annealing, which are used as the negative electrodes for ICRFBs. The resulting Bi NPs react with H+ to form intermediates and greatly inhibit the parasitic HER. In addition, the combined effect of Bi and N dopants on the surface of GF dramatically increases the electrochemical activity of Fe2+/Fe3+ and Cr3+/Cr2+, reduces the charge transfer resistance, and increases the mass transfer rate compared to plain GF. At the optimum Bi/N ratio of 2, a high coulombic efficiency of up to 97.7% is maintained even for 25 cycles at different current densities, the energy efficiency reaches 85.8% at 60.0 mA cm−2, exceeding many other reported materials, and the capacity reaches 862.7 mAh L−1 after 100 cycles, which is about 5.3 times that of bare GF.
Iron-chromium redox flow batteries (ICRFBs) use abundant and inexpensive chromium and iron as the active substances in the electrolyte and have great potential as a cost-effective and large-scale energy storage system. However, they are still plagued by several issues, such as the low electrochemical activity of Cr3+/Cr2+ and the occurrence of the undesired hydrogen evolution reaction (HER). We report the synthesis of amorphous bismuth (Bi) nanoparticles (NPs) immobilized on N-doped graphite felts (GFs) by a combined self-polymerization and wet-chemistry reduction strategy followed by annealing, which are used as the negative electrodes for ICRFBs. The resulting Bi NPs react with H+ to form intermediates and greatly inhibit the parasitic HER. In addition, the combined effect of Bi and N dopants on the surface of GF dramatically increases the electrochemical activity of Fe2+/Fe3+ and Cr3+/Cr2+, reduces the charge transfer resistance, and increases the mass transfer rate compared to plain GF. At the optimum Bi/N ratio of 2, a high coulombic efficiency of up to 97.7% is maintained even for 25 cycles at different current densities, the energy efficiency reaches 85.8% at 60.0 mA cm−2, exceeding many other reported materials, and the capacity reaches 862.7 mAh L−1 after 100 cycles, which is about 5.3 times that of bare GF.
2024, 39(1): 142-151.
doi: 10.1016/S1872-5805(24)60834-6
摘要:
The nitrate reduction reaction (NtRR) has been demonstrated to be a promising way for obtaining ammonia (NH3) by converting NO3− to NH3. Here we report the controlled synthesis of cobalt tetroxide/graphdiyne heterostructured nanowires (Co3O4/GDY NWs) by a simple two-step process including the synthesis of Co3O4 NWs and the following growth of GDY using hexaethynylbenzene as the precursor at 110 °C for 10 h. Detailed scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman characterization confirmed the synthesis of a Co3O4/GDY heterointerface with the formation of sp-C―Co bonds at the interface and incomplete charge transfer between GDY and Co, which provide a continuous supply of electrons for the catalytic reaction and ensure a rapid NtRR. Because of these advantages, Co3O4/GDY NWs had an excellent NtRR performance with a high NH3 yield rate (YNH3) of 0.78 mmol h−1 cm−2 and a Faraday efficiency (FE) of 92.45% at −1.05 V (vs. RHE). This work provides a general approach for synthesizing heterostructures that can drive high-performance ammonia production from wastewater under ambient conditions.
The nitrate reduction reaction (NtRR) has been demonstrated to be a promising way for obtaining ammonia (NH3) by converting NO3− to NH3. Here we report the controlled synthesis of cobalt tetroxide/graphdiyne heterostructured nanowires (Co3O4/GDY NWs) by a simple two-step process including the synthesis of Co3O4 NWs and the following growth of GDY using hexaethynylbenzene as the precursor at 110 °C for 10 h. Detailed scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman characterization confirmed the synthesis of a Co3O4/GDY heterointerface with the formation of sp-C―Co bonds at the interface and incomplete charge transfer between GDY and Co, which provide a continuous supply of electrons for the catalytic reaction and ensure a rapid NtRR. Because of these advantages, Co3O4/GDY NWs had an excellent NtRR performance with a high NH3 yield rate (YNH3) of 0.78 mmol h−1 cm−2 and a Faraday efficiency (FE) of 92.45% at −1.05 V (vs. RHE). This work provides a general approach for synthesizing heterostructures that can drive high-performance ammonia production from wastewater under ambient conditions.
2024, 39(1): 152-163.
doi: 10.1016/S1872-5805(24)60824-3
摘要:
Designing efficient and robust catalysts for hydrogen evolution reaction (HER) is imperative for saline water electrolysis technology. A catalyst composed of CoxP nanowires array with N-doped carbon nanosheets (NC) was fabricated on Ni foam (NF) by an in-situ growth strategy. The material is designated as NC/CoxP@NF. In the preparation process, Co(OH)2 nanowires were transformed into a metal organic framework of cobalt (ZIF-67) on NF by the dissolution-coordination of endogenous Co2+ and 2-methylimidazole. The resulting cactus-like microstructure gives NC/CoxP@NF abundant exposed active sites and ion transport channels, which improve the HER catalytic reaction kinetics. Furthermore, the interconnected alternating nanowires and free-standing nanosheets in NC/CoxP@NF improve its structural stability, and the formation of surface polyanions (phosphate) and a NC nanosheet protective layer improve the anti-corrosive properties of catalysts. Thus, the NC/CoxP@NF has an excellent performance, requiring overpotentials of 107 and 133 mV for HER to achieve 10 mA cm−2 in 1.0 mol L−1 KOH and 1.0 mol L−1 KOH + 0.5 mol L−1 NaCl, respectively. This in-situ transformation strategy is a new way of constructing highly-efficient HER catalysts for saline water electrolysis.
Designing efficient and robust catalysts for hydrogen evolution reaction (HER) is imperative for saline water electrolysis technology. A catalyst composed of CoxP nanowires array with N-doped carbon nanosheets (NC) was fabricated on Ni foam (NF) by an in-situ growth strategy. The material is designated as NC/CoxP@NF. In the preparation process, Co(OH)2 nanowires were transformed into a metal organic framework of cobalt (ZIF-67) on NF by the dissolution-coordination of endogenous Co2+ and 2-methylimidazole. The resulting cactus-like microstructure gives NC/CoxP@NF abundant exposed active sites and ion transport channels, which improve the HER catalytic reaction kinetics. Furthermore, the interconnected alternating nanowires and free-standing nanosheets in NC/CoxP@NF improve its structural stability, and the formation of surface polyanions (phosphate) and a NC nanosheet protective layer improve the anti-corrosive properties of catalysts. Thus, the NC/CoxP@NF has an excellent performance, requiring overpotentials of 107 and 133 mV for HER to achieve 10 mA cm−2 in 1.0 mol L−1 KOH and 1.0 mol L−1 KOH + 0.5 mol L−1 NaCl, respectively. This in-situ transformation strategy is a new way of constructing highly-efficient HER catalysts for saline water electrolysis.
2024, 39(1): 164-172.
doi: 10.1016/S1872-5805(24)60832-2
摘要:
The precise change of the electronic structure of active metals using low-active supports is an effective way of developing high-performance electrocatalysts. The electronic interaction of the metal and support provides a flexible way of optimizing the catalytic performance. We have fabricated an efficient hydrogen evolution reaction (HER) electrocatalyst, in which Ir nanoclusters are uniformly loaded on a nitrogen-doped carbon framework (Ir@NC). The synthesis process entails immersing an annealed zeolitic imidazolate framework-8 (ZIF-8), prepared at 900 °C as a carbon source, into an IrCl3 solution, followed by a calcination-reduction treatment at 400 °C under a H2/Ar atmosphere. The three-dimensional porous structure of the nitrogen-doped carbon framework exposes more active metal sites, and the combined effect of the Ir clusters and the N-doped carbon support efficiently changes the electronic structure of Ir, optimizing the HER process. In acidic media, Ir@NC has a remarkable HER electrocatalytic activity, with an overpotential of only 23 mV at 10 mA cm−2, an ultra-low Tafel slope (25.8 mV dec−1) and good stability for over 24 h at 10 mA cm−2. The high activity of the electrocatalyst with a simple and scalable synthesis method makes it a highly promising candidate for the industrial production of hydrogen by splitting acidic water.
The precise change of the electronic structure of active metals using low-active supports is an effective way of developing high-performance electrocatalysts. The electronic interaction of the metal and support provides a flexible way of optimizing the catalytic performance. We have fabricated an efficient hydrogen evolution reaction (HER) electrocatalyst, in which Ir nanoclusters are uniformly loaded on a nitrogen-doped carbon framework (Ir@NC). The synthesis process entails immersing an annealed zeolitic imidazolate framework-8 (ZIF-8), prepared at 900 °C as a carbon source, into an IrCl3 solution, followed by a calcination-reduction treatment at 400 °C under a H2/Ar atmosphere. The three-dimensional porous structure of the nitrogen-doped carbon framework exposes more active metal sites, and the combined effect of the Ir clusters and the N-doped carbon support efficiently changes the electronic structure of Ir, optimizing the HER process. In acidic media, Ir@NC has a remarkable HER electrocatalytic activity, with an overpotential of only 23 mV at 10 mA cm−2, an ultra-low Tafel slope (25.8 mV dec−1) and good stability for over 24 h at 10 mA cm−2. The high activity of the electrocatalyst with a simple and scalable synthesis method makes it a highly promising candidate for the industrial production of hydrogen by splitting acidic water.
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