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A review of nitrogen-doped carbon materials for lithium-ion battery anodes
Majid Shaker, Ali Asghar Sadeghi Ghazvini, Taieb Shahalizade, Mehran Ali Gaho, Asim Mumtaz, Shayan Javanmardi, Reza Riahifar, MENG Xiao-min, JIN Zhan, GE Qi
 doi: 10.1016/S1872-5805(23)60724-3
Abstract(125) HTML(18) PDF(33)
One of the most important research areas that has captured global attention is the replacement of graphite anode with other carbon materials such as hard carbon, activated carbon, carbon nanotubes, graphene, porous carbon, and carbon fiber. Although such materials have shown better electrochemical performance for lithium storage compared to graphite, their is plenty of room for improvement. One of the most effective approaches is to dope heteroatoms (e. g. nitrogen) in the structure of carbon materials to enhance their electrochemical performance when used as anode in lithium ion batteries. In this review paper, we first describe how N doping has a positive effect on lithium storage and then provide numerous selected examples of this approach being applied to various carbon materials. Then, in addition to the conventional characterization methods, the specific characterization of doped N in the structure of different carbon materials through X-ray photoelectron spectroscopy and scanning tunneling microscopy is presented, as they are able to characterize N in these structures with high (atomic) resolution. Finally, a statistical analysis is performed to discover the influence that the amount of doped N has on the specific capacity of N-doped carbon materials.
Preparation of carbon dots from natural 3D porous electrode by electrochemical oxidation and their application in Na-batteries
LI Rui-lin, ZHAO Zong-bin, LENG Chang-yu, LI Yong, AI Li-shen, SUN Yang, WANG Xu-zhen, QIU Jie-shan
 doi: 10.1016/S1872-5805(22)60644-9
Abstract(99) HTML(82) PDF(18)
Carbon dots (CDs) have attracted increasing attention due to their high specific surface area, good dispersion, abundant surface functional groups, low biotoxicity and photoluminescence properties. However, the preparation of CDs with large-scale is still a great challenge because of the high cost and environmental problem, which seriously limit their practical application. In the present work, carbonized corncobs were used as the starting materials for the preparation of CDs by electrochemical oxidation. The natural porous structures with well-developed channels allow the filling of electrode inside with electrolyte, and the electrochemical oxidation takes place both on the inside and outside surface of the carbonized corncob, achieving a CDs output of 79.8 mg h−1 g−1 electrode materials at 1 A. The corncob-based CDs were combined with graphene oxide (GO) to give CDs/rGO composite aerogel by hydrothermal method. After heat treatment at 600 °C, the obtained materials were used in the sodium ion battery as the anode, which achieves a specific capacity of 263.3 mAh g−1 after 1000 cycles at 1 A g−1. This work proposes a new pathway for the preparation and application of CDs.
Graphene material with KI-modified pore structure and its electrochemical capacitors application
LUO Ming-yu, XU Ruo-gu, SHI Ying, WANG Yu-zuo, LI Feng
 doi: 10.1016/S1872-5805(23)60714-0
Abstract(80) HTML(55) PDF(27)
The application of electrochemical capacitors is greatly limited by poor volumetric energy density. The key for improving volumetric energy density is to develop porous yet compact carbon materials. In recent years, capillary densification has been used as a main method to balance the density and porosity of porous carbon for high volumetric performance. But there are still deficiencies in fine tuning of pore structure, which limits the compatibility of porous carbon with high-voltage ionic liquids. Herein, a potassium iodide-assisted capillary densification strategy is proposed. During synthesis, graphene oxides were dispersed in the potassium iodide solution following a hydrothermal treatment at 180 °C for 6 h. As-obtained hydrogel was dried under vacuum (0.01 MPa) at 60 °C for 72 h. By this, potassium iodide was preloaded into the matrix of compact graphene before capillary densification, which could be a regulator to tune the pore structure. Besides, the electrochemical characterizations indicated that the ionic-accessible surface area and pseudo-capacitance of porous carbon were enhanced by this method. As a result, the as-obtained potassium iodide/graphene hybrid achieved both high electrode density of 0.96 g cm−3 and volumetric performance of 115 F cm−3 (at 1 A g−1) in ionic liquid electrolyte. Besides, the symmetric cell assembled by this hybrid delivered a high volumetric energy density of 19.6 Wh L−1.
Research progress on freestanding carbon-based anodes for sodium energy storage
HOU Zhi-dong, GAO Yu-yang, ZHANG Yu, WANG Jian-gan
 doi: 10.1016/S1872-5805(23)60725-5
Abstract(135) HTML(26) PDF(20)
Sodium-ion batteries (SIBs) have received extensive research interests as an important supplement of lithium-ion batteries in the electrochemical energy storage field by virtue of abundant reserves and low-cost advantages of sodium element. In the past few years, carbon and their composite materials as anode materials have shown excellent sodium storage properties through structural design and composition regulation. The increasing popularity of wearable electronics has put forward higher requirements for electrode materials. Free-standing electrode is able to eliminate the massive use of electrochemical inactive binders and conductive additives, thereby favorably increasing the overall energy density of the battery system. In this review, the research progress of carbon materials (such as carbon nanofibers, carbon nanotubes, graphene, etc.) and their composites (metallic compounds and alloy-type materials) are summarized. The preparation strategies and electrochemical properties of free-standing carbon-based anodes with and without substrates are categorized and reviewed. Finally, the perspectives about research directions and future developments of free-standing carbon-based anodes for SIBs are proposed.
Photothermal catalysis: principles, materials and applications in CO2 reduction
ZHAO Shan-hai, WANG Hai-bing, LI Qiang, DING Hao, QIAN Cheng, WANG Qi, LI Hui-yu, JIANG Feng, CAO Hai-jing, LI Chun-he, ZHU Yan-yan
 doi: 10.1016/S1872-5805(23)60722-X
Abstract(82) HTML(34) PDF(33)
As the massive emission of CO2 caused by the consumption of carbon has become the focus of human society, the development of renewable energy and the reduction emission of CO2 has become one of the most urgent issues to deal with in the world. As the most ideal clean energy on earth, solar energy has become a hot topic of current research. If abundant solar energy can be used to convert carbon dioxide into valued carbon-based chemicals, these two problems can be solved at the same time. There are many literatures on photocatalysis or thermal catalysis in the reduction of CO2. However, there is little research on photothermal catalysis in the reduction of CO2. In this paper, the research status of photothermal catalysis in the reduction of CO2 is summarized, showing the concept and principle of photothermal catalysis in the reduction of CO2, the classification of catalysts (new carbon materials, oxide materials, metal sulfide materials, MOF materials, layered double hydroxide materials), the modification of catalysts, and their applications in reduction of CO2. Finally, the development trend of the catalyst is forecasted. The rational development of carbon-based chemicals may help us reduce the consumption of traditional energy, reduce carbon emissions and realize the recycling of carbon.
Review on wearable supercapacitors fabricated by highly flexible conductive fiber materials
Nujud Badawi M, Namrata Agrawal, Syed Farooq Adil, S Ramesh, K Ramesh, Shahid Bashir
 doi: 10.1016/S1872-5805(23)60721-8
Abstract(176) HTML(33) PDF(9)
Supercapacitors fabricated using fiber materials are becoming noticeable electrochemical energy storage devices as they are flexible, light weight and have high energy density. These are used in electronic systems, such as information sensing, data computation and communication. These flexible supercapacitors are applied in electronic textiles because these fabric-based supercapacitors (SCs) can achieve higher power density than standard parallel plate capacitors and batteries. In this review, the effects of carbon nanotubes (CNTs), graphene and poly(3,4- ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS) on the electrochemical performance of fibers based on their compositions, spinning and fabrication conditions have been explained in detail in the context of wearable energy storage devices.
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
Abstract(86) HTML(52) PDF(12)
As the sulfur host as a reactor for redox reactions and determines the electrochemical properties of the sulfur cathode, tailor-made fabrication of sulfur host is very effective to solve the main challenges of lithium-sulfur (Li-S) batteries, such as the shuttle effect and sluggish redox kinetics. 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 with each other forming 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 through effective catalysis 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
Abstract(96) HTML(80) PDF(11)
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 has been investigated by mutliple techniques, including interlaminar shear strength (ILSS), elemental and functional group analysis, thermal gravimetric analysis, and differential scanning calorimetry. The results show the polyurethane sizing agent 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 to 46.4 MPa) compared with that of the oxidized carbon fiber reinforced counterpart. 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 that the sizing agent can interact with the oxygen-contained functional groups on the oxidized carbon fiber surface and form hydrogen bonds with the matrix resin. Upon heating at 170 °C, the blocking groups in the sizing agent are unblocked to expose the isocyanate roots that can react with the carbamate of the matrix to generate allophanate. It can draw the conclusions that the polyurethane sizing agent is suitable to improve the interfacial performance of carbon fiber reinforced polyurethane resin composites. Unsealing the sizing agent at high temperature after curing can further improve the interfacial performance of the composite.
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
Abstract(54) HTML(70) PDF(10)
In this study, a novel pantograph carbon slider (PCS) was designed by incorporating sulfonated graphene (SG), resulting in the enhancement of 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 lowered by 50.0% in the normal environment and 51.0% in a rainy weather environment, compared with the control group. In addition, the flexural strength of the samples with SG was 41.8% higher than to those without SG. Moreover, the dragging effect of SG decreased the number of random cracks and increased the compactness of fracture surface of the slider materials. These changes markedly inhibited the electro-erosion of the PCS, thus improving mechanical and wear resistance significantly.
Preparation and performance of graphene/Ni-NiO@C as an anode material of a lithium-ion battery
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
Abstract(264) HTML(118) PDF(33)
Graphene/Ni-NiO@C was prepared by dissolving nickel acetate and glucose in water, mixed with a graphene oxide (GO) aqueous suspension, hydrothermal treated at 180 °C for 24 h, carbonized at 700 °C for 3h in Ar and calcined at 300 °C for 3 h in air. Results indicated that Ni(OH)2 formed during hydrothermal treatment was coated with char derived from glucose and converted to metallic Ni in carbonization, which was partly oxidized to NiO in calcination. When used as the anode material of a lithium-ion battery, it exhibited a high initial capacity of 711.6 mA h g−1, which increased to 772.1 mA h g−1 after 300 cycles. As a comparison, the sample without adding GO had a much lower initial capacity of 584.7 mA h g−1, which decreased to 148.8 mA h g−1 after 300 cycles. Carbon coating on Ni-NiO nanoparticles inhibited their aggregation. GO addition led to the formation of a conducting network, alleviated the large volume expansion during lithiation, restrained the electrode cracking during cycling and increased surface area for easy access of the electrolyte. These factors jointly contributed to the apparent improvement in the electrochemical performance of the graphene/Ni-NiO@C anode.
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
Abstract(93) HTML(82) PDF(16)
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, 13C-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.
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
Abstract(628) HTML(241) PDF(72)
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.
Topography changes and microstructural evolution of nuclear graphite (IG-110) induced by Xe26+ irradiation
ZHANG He-yao, CHENG Jin-xing, SONG Jin-liang, YIN Hui-qin, TANG Zhong-feng, LIU Zhan-jun, LIU Xiang-dong
 doi: 10.1016/S1872-5805(23)60708-5
Abstract(40) HTML(41) PDF(8)
As a key material in nuclear reactors, the microstructure of nuclear graphite is affected by the high-flux irradiation in reactors. The damage behavior of nuclear graphite by irradiation is important for the safe operation of reactors. In order to understand the damage behavior of nuclear graphite by irradiation, IG-110 nuclear graphite, as a representative of nuclear graphite, was chosen to investigate the evolution of morphology and microstructure caused by 7 MeV Xe26+ irradiation. The topography and microstructure of IG-110 were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, Raman spectroscopy and nano-indentation. Results indicate that after 7 MeV Xe26+ irradiation at a dose of 0.11 dpa, the ridge-like structure appears on the surface of the IG-110 graphite, mainly in the binder region, and the surface roughness increases slightly. With a further increase of the irradiation dose, the ridge-like structure also appears in the filler region. At a dose of 0.55 dpa, the shrinkage of pores increases accompanied by closing of pores, and the surface roughness also increases. 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 graphene sheets increases with the increase of irradiation dose. The mechanical properties of IG-110 graphite increase first then decrease with increasing the irradiation dose. The increase of mechanical properties is caused by dislocation pinning and closing of fine pores, while the decrease of mechanical properties is attributed to the increase of porosity and the generation of the amorphous structure.
Effect of CVI treatment on Flexural Properties of C/C-SiC Composites Prepared by PIP Method
JIA Lin-tao, WANG Meng-qian, GUO Xiao-feng, ZHU Jie, LI Ai-jun, PENG Yu-qing
 doi: 10.1016/S1872-5805(23)60732-2
Abstract(2) HTML(7) PDF(3)
2D laminated carbon cloth as reinforcement, furfurone resin mixed with three inorganic powders such as silicon powder, carbon powder and silicon carbide powder, carbon/carbon-silicon carbide (C/C-SiC) composites were prepared through impregnation, hot-pressing with curing, carbonization and high-temperature heat treatment processes. The effects of addition of silicon powder, carbon powder and silicon carbide powder as well as subsequent chemical vapor infiltration (CVI) treatment on density, microstructure and bending strength of C/C-SiC composites were studied by scanning electron microscope (SEM), multifunctional density , X-ray diffraction (XRD) and universal mechanical testing machine. The results showed that the silicon carbide particles formed by the addition of silicon powder, carbon powder and silicon carbide powder had the effect of particle dispersion enhancement on the composite material. Under three-point bending load, C/C-SiC composites show pseudoplastic fracture mode and interlaminar cracking. After 10 h CVI treatment of C/C-SiC composites, the pyrolytic carbon can be used as the interface between carbon fiber and resin carbon matrix. The density and flexural strength of C/C-SiC composites were maximum increased by 4.98% and 38.86%, respectively.
Reversible surface modification of carbon fibers by a ferrocene-based surfactant
ZHANG Xiao-fang, YAO Ting-ting, LIU Yu-ting, WU Gang-ping
 doi: 10.1016/S1872-5805(23)60728-0
Abstract(4) HTML(3) PDF(3)
Carbon fibers (CFs) were surface-modified by a surfactant (ferrocenemethyl)dodecyldimethylammonium bromide (FDDA) for changing the surface properties. Results showed that the FDDA adsorbed onto CFs could be electrochemically desorbed by a potentiostatic electro-oxidation method. The FDDA adsorption isotherm was attributed to the formation of multi-molecular layers mainly by non-electrostatic interactions. The adsorption and desorption of FDDA on CFs have little effect on the tensile strength of CFs. Furthermore, the effects of FDDA modification on the interfacial properties of CF/epoxy composites were evaluated by a single-filament fragmentation test. Compared with the un-modified CFs, the FDDA-modified CFs exhibited significantly improved interfacial adhesion properties in composites. This method provides a potential approach for preparing recyclable CF/resin composites.
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
Abstract(165) HTML(106) PDF(24)
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.
Preparation of porous graphitic carbon and its dual-ion capacitance energy storage mechanism
ZHAN Chang-zhen, ZENG Xiao-jie, LV Rui-tao, SHEN Yang, HUANG Zheng-hong, KANG Fei-yu
 doi: 10.1016/S1872-5805(23)60727-9
Abstract(36) HTML(14) PDF(12)
Porous graphitic carbon (PGC) with a partially graphitized structure and porous structure is synthesized using citrate as precursors. While employed as positive electrode material, it shows dual-ion hybrid capacitance mechanism, which combines electronic double-layer capacitor behavior in lithium-ion capacitor and anion intercalation/de-intercalation behavior in dual-ion battery. Two types of mechanisms are observed in the electrochemical characterization process, and the energy performance of citrate-based PGC electrode is significantly increased due to its enhanced conductivity and the additional plateau capacity contributed by the anion intercalation reaction at high potential.
Advances of sulfur-doped carbon materials as anode for sodium-ion batteries
XIE Jin-ming, ZHUANG Rong, DU Yu-xuan, PEI Yong-wei, TAN De-ming, XU Fei
 doi: 10.1016/S1872-5805(22)60630-9
Abstract(1223) HTML(306) PDF(134)
Sodium-ion batteries (SIBs) are regarded as one of the most promising candidates for the post-lithium-ion batteries (LIBs) era, due to the abundant nature and low cost of sodium, and similar operating principles to LIBs. Featured by a low sodium intercalation platform, high capacity, and good stability, carbon anode materials appear to be the key to practical applications. In general, heteroatoms doping (e.g., sulfur, nitrogen, phosphorus, oxygen, boron doping) has been proved to be an effective way to tune the physical and electrochemical properties, showing great potential in energy storage performance. Among them, sulfur doping has been widely studied in the modification of carbon materials, using a large covalent radius to expand the interlayer spacing of carbons, and increase defects and active sites for sodium storage. The objective of this review is to briefly summarize the research progress in the design, synthesis, and electrochemical properties of sulfur-doped carbon anodes for SIBs, including the sodium storage mechanism, preparation strategies, and structural modulating of carbon materials by sulfur doping, aiming to help readers comprehensively learn the fabrication of sulfur-doped carbon anodes with a large specific capacity, high rate capability, and long cycling life in SIBs. Furthermore, the key problems and possible solutions of sulfur-doped carbon anodes are presented, and a perspective of the research directions is proposed.
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2023, 38(1).  
Abstract(153) HTML(23) PDF(60)
2023, 38(1): .  
Abstract(80) HTML(19) PDF(22)
Recent advances in porous carbons for electrochemical energy storage
LIU Yu-si, MA Chao, WANG Kai-xue, CHEN Jie-sheng
2023, 38(1): 1-17.   doi: 10.1016/S1872-5805(23)60710-3
Abstract(305) HTML(95) PDF(141)
Porous carbons are widely used in the field of electrochemical energy storage due to their light weight, large specific surface area, high electronic conductivity and structural stability. Over the past decades, the construction and functionalization of porous carbons have seen great progress. This review summarizes progress in the use of porous carbons in different energy storage devices, such as lithium-ion, lithium-oxygen, lithium-sulfur, and lithium-metal batteries for anode protection, sodium-ion and potassium-ion batteries, supercapacitors and metal ion capacitors. Methods for the synthesis and functionalization of porous carbons are discussed and the effects of their pore texture on the electrochemical performance of different energy storage systems are outlined. Strategies for their structural control are proposed, and the challenges and prospects for their use in energy storage devices are discussed.
A review of fibrous graphite materials: graphite whiskers, columnar carbons with a cone-shaped top, and needle- and rods-like polyhedral crystals
LIU Yu-hong, MA Zhao-kun, HE Yan, WANG Yue, ZHANG Xing-wei, SONG Huai-he, LI Cui-xia
2023, 38(1): 18-39.   doi: 10.1016/S1872-5805(23)60719-X
Abstract(219) HTML(69) PDF(135)
Fibrous graphite materials are highly attractive due to their unique morphologies, high degree of orientation of their graphite microcrystallites, extremely good mechanical and conductive properties, fascinating growth mechanisms, diverse preparation methods and potential applications. This review summarizes the preparation methods, Raman spectra and the growth mechanisms of graphite whiskers, columnar carbons with cone-shaped top cones, and needle- and rod-like polyhedral crystals, and their optical, electrical and magnetic properties and applications are outlined.
Biomass-derived carbon anodes for sodium-ion batteries
HUANG Si, QIU Xue-qing, WANG Cai-wei, ZHONG Lei, ZHANG Zhi-hong, YANG Shun-sheng, SUN Shi-rong, YANG Dong-jie, ZHANG Wen-li
2023, 38(1): 40-72.   doi: 10.1016/S1872-5805(23)60718-8
Abstract(670) HTML(214) PDF(283)
Sodium-ion batteries (SIBs) have attracted tremendous attention for large-scale stationary grid energy storage. With the upcoming commercialization of SIBs in the foreseeable future, developing high-performance carbon anodes from sustainable biomass is becoming increasingly important in the preparation of cost-effective SIBs. This review summarizes advanced carbon anodes for SIBs derived from various lignocellulose biomass waste. The history of our understanding of sodium storage mechanisms in carbon anodes is first discussed to clarify their structure-performance relationships. Conventional preparation strategies including pore structure design, heteroatom doping, control of the graphitic structure, and morphology control and their effects on the sodium storage capability of biomass-derived carbon anodes are then discussed. Finally, the practical applications, future research directions and challenges for the use of biomass-derived carbon anodes for SIBs are discussed from the aspects of synthesis methods, microstructure control and production costs.
Recent progress in the research and development of natural graphite for use in thermal management, battery electrodes and the nuclear industry
DUAN Sheng-zhi, WU Xiao-wen, WANG Yi-fan, FENG Jian, HOU Shi-yu, HUANG Zheng-hong, SHEN Ke, CHEN Yu-xi, LIU Hong-bo, KANG Fei-yu
2023, 38(1): 73-95.   doi: 10.1016/S1872-5805(23)60717-6
Abstract(251) HTML(120) PDF(140)
Natural graphite has many excellent properties such as high thermal and electrical conductivities, high temperature resistance, corrosion resistance, and radiation tolerance. It is widely used in many fields such as thermal management, battery electrodes, and the nuclear industry. The carbon content is an important factor that limits the applications of natural graphite minerals, but the impurities are difficult to remove from high-grade graphite minerals. This review discusses the types of natural graphite and mineral resources, followed by a discussion of traditional graphite purification processes and new methods to obtain high-purity graphite. Recent research on the development of natural graphite for use in thermal management, battery electrodes and the nuclear industry are summarized and the future applications of natural graphite are discussed.
Progress in the graphitization and applications of modified resin carbons
YANG Ping-jun, LI Tie-hu, LI Hao, DANG A-lei, YUAN Lei
2023, 38(1): 96-110.   doi: 10.1016/S1872-5805(23)60715-2
Abstract(321) HTML(137) PDF(172)
Resin carbons have favorable mechanical, electrical and thermal properties, and are widely used as structural and functional materials in aviation, aerospace and energy storage, etc. The inherent molecular structures of resins make their graphitization difficult, which greatly limits wide applications. Research progress on the graphitization and applications of resin carbons in recent years are reviewed. Their graphitized carbon content can be increased and their graphitization temperature reduced by adding catalysts, carbon nanomaterials and easily graphitized co-carbonization agents. Most studies have been devoted to increasing their graphitized carbon content using catalysts and carbon nanomaterials. The degree of graphitization of resin carbons at temperatures below 1400 °C can reach 74% by adding a catalyst, and above 2000 °C by adding carbon nanomaterials. Co-carbonization agents may increase their degree of graphitization and also their carbon yield. The thermal and electrical conductivities of carbon/carbon composites could be improved by increasing the degree of graphitization of resin carbons, and this would improve the conductivity, rate performance and power density of supercapacitors and secondary batteries. Challenges and research prospects for the graphitization of resin carbons and their applications are discussed.
Recent progress in increasing the electromagnetic wave absorption of carbon-based materials
LI Wen-yi, GAO Ming-yang, MIAO Yang, WANG Xiao-min
2023, 38(1): 111-129.   doi: 10.1016/S1872-5805(23)60703-6
Abstract(474) HTML(148) PDF(171)
High-performance electromagnetic wave absorbing materials (EWAMs) are expected to solve electromagnetic wave radiation problems in both the military and civil fields. The desired features of EWAMs include strong absorption over a broad bandwidth, low density, thinness, oxidation resistance, wear resistance, ability to withstand high-temperatures and high strength. Carbon-based materials, including nanostructures and composites, are attractive alternatives to EWAMs because of their unique structures and properties. We summarize recent achievements in carbon-based EWAMs, including different dimensional (0D, 1D, 2D and 3D) carbon nanostructures and various types of carbon composites (dielectric/carbon, magnetic/carbon) and hybrids. The factors affecting the absorption of electromagnetic microwaves include electrical conductivity (σ), permittivity (ε) and permeability (μ) are discussed based on the electromagnetic microwave absorption mechanisms. Representative carbon-based EWAMs and the corresponding mechanisms of improving their electromagnetic microwave absorption are highlighted and analyzed. Strategies for the modification of carbon-based EWAMs are summarized and research trends are proposed.
Status and development trends for fluorinated carbon in China
FENG wei
2023, 38(1): 130-142.   doi: 10.1016/S1872-5805(23)60716-4
Abstract(258) HTML(139) PDF(155)
Fluorinated carbon (CFx) are a class of carbon derivatives with C―F bonds formed by the fluorination of carbon materials, including graphite, graphene, and carbon nanotubes. Because of their different carbon skeletons with polar C―F bonds, they have many excellent properties such as chemical stability, band gap adjustability and superhydrophobicity. Based on their structure and properties, we review the status and development trends of CFx for use in chemical energy, lubrication and semiconductors in recent years in China. We discuss the industrialization of CFx in China and the main reasons for their limited use in civil fields, as well as the problems and future development opportunities of CFx, which suggests some practical applications.
Research articles
Nitrogen doped hollow porous carbon fibers derived from polyacrylonitrile for Li-S batteries
NIU Jing-yi, JING De-qi, ZHANG Xing-hua, SU Wei-guo, ZHANG Shou-chun
2023, 38(1): 143-153.   doi: 10.1016/S1872-5805(22)60615-2
Abstract(279) HTML(125) PDF(106)
Hollow porous carbon fibers for Li-S battery electrodes were prepared by the KOH activation of carbon prepared from hollow polyacrylonitrile fibers. The fibers had a high specific surface area of 2 491 m2·g−1, a large pore volume of 1.22 cm3·g−1 and an initial specific capacity of 330 mAh·g−1 at a current density of 1 C. To improve their electrochemical performance, the fibers were modified by treatment with hydrazine hydrate to prepare nitrogen-doped hollow porous carbon fibers with a specific surface area of 1 690 m2·g−1, a pore volume of 0.84 cm3·g−1 and a high nitrogen content of 8.81 at%. Because of the increased polarity and adsorption capacity produced by the nitrogen doping, the initial specific capacity of the fibers was increased to 420 mAh·g−1 at a current density of 1 C.
The synthesis of iron-nitrogen sites embedded in electrospun carbon nanofibers with an excellent oxygen reduction reaction activity in alkaline/acidic media
XU Xiang-xiang, ZHANG Nian-chao, WANG Jun-ying, WANG Jun-zhong
2023, 38(1): 154-161.   doi: 10.1016/S1872-5805(22)60649-8
Abstract(192) HTML(119) PDF(77)
Metal-nitrogen carbon catalysts have received great attention in the field of gas-evolving electrocatalysis due to their high activity, large specific surface area and efficient gas diffusion paths. A solution of porphyrin iron, g-C3N4 and polyacrylonitrile in N,N-dimethylformamide was sonicated and electrospun into doped polyacrylonitrile nanofibers (NFs), and the NFs were then stabilized and carbonized at 900 °C to prepare Fe-N/CNF catalyst for oxygen reduction reaction (ORR). It was found that the addition of g-C3N4 to the electrospinning precursor led to the formation of abundant Fe-N species in Fe3+ and Fe2+ valence states, while Fe3C nanoparticles were formed without adding g-C3N4. Compared to Fe3C/CNF prepared without g-C3N4, the Fe-N/CNF catalyst presents an 4e improved oxygen reduction reaction activity in both alkaline and acidic media. Furthermore, as a cathode in Zn-air batteries, the Fe-N/CNF catalyst exhibits high performance with an open-circuit voltage of 1.49 V, a power density of 146 mW cm−2 and a specific capacity of 703 mAh g−1. This work suggests a way to prepare metal-nitrogen-carbon catalysts for energy-related electrocatalytic applications.
Preparation of carbon nanotube/cellulose hydrogel composites and their uses in interfacial solar-powered water evaporation
WANG Xue, SUN Yang, ZHAO Guan-yu, WANG Xu-zhen, QIU Jie-shan
2023, 38(1): 162-172.   doi: 10.1016/S1872-5805(22)60621-8
Abstract(488) HTML(231) PDF(132)
Cellulose extracted from corncobs, a bulk agricultural waste product, by a solvent at −12 °C, was composited with carbon nanotubes (CNTs) with excellent light absorption properties to construct CNT/cellulose hydrogel composites. Taking advantage of the superior water retention ability and degradability of cellulose hydrogels, and the high-efficiency solar-thermal conversion performance, excellent mechanical properties and biocompatibility of CNTs, CNT/cellulose hydrogel composites are used in water purification by interfacial solar-powered evaporation. The effects of the addition of CNTs on the solar energy absorption, mechanical properties and interfacial solar-thermal water evaporation efficiency of the composites were investigated. With an optimum CNT content of 0.2 wt.%, the composite had an average evaporation rate of ~1.52 kg m−2 h−1 and a solar-steam conversion efficiency of about 92%. After continuous evaporation in seawater for 8 h, the evaporation rate of the composite remained at about 1.37 kg m−2 h−1 without salt precipitation, indicating its strong resistance to salt. The quality of the purified water was superior to the WHO and EPA standards for drinking water. When the composite was used in concentrated acid/alkaline aqueous systems, dye wastewater and heavy metal ion polluted water, the evaporation rates remained in the range 1.30-1.40 kg m−2 h−1, and the solar-steam conversion efficiencies reached 80-86%. The retention rates for both organic pollutants and salt were as high as 99.9%, confirming the evaporation stability of the composite. This work indicates that an evaporator based on the composite has broad application prospects in the fields of seawater desalination and industrial wastewater purification.
An innovative and efficient method for the preparation of mesocarbon microbeads and their use in the electrodes of lithium ion batteries and electric double layer capacitors
DONG Si-lin, YANG Jian-xiao, CHANG Sheng-kai, SHI Kui, LIU Yue, ZOU Jia-ling, LI Jun
2023, 38(1): 173-189.   doi: 10.1016/S1872-5805(22)60606-1
Abstract(271) HTML(130) PDF(100)
An innovative and efficient method for preparation of mesocarbon microbeads (MCMBs) was developed based on the dripping behavior and rheological properties of molten pitch during melt-spinning, where a string of beads was formed after the pitch was extruded from spinnerets and dropped into a receiving solvent (tetrohydrofuran or water). The pitch droplets were first carbonized, then activated by KOH or graphitized at 2800 °C to prepare A-MCMBs or G-MCMBs, respectively, and these were respectively used as the electrode materials for electric double layer capacitors (EDLCs) and lithium-ion batteries (LIBs). Results showed that both MCMB-W prepared using water as the receiving solvent and MCMB-T prepared using tetrohydrofuran as the receiving solvent had a spherical shape with sizes of 1-2 μm. A-MCMB-T had a high specific surface area (1 391 m2 g−1), micropore volume (0.55 cm3 g−1) and mesopore volume (0.24 cm3 g−1), with a 30% higher specific capacitance than an activated mesophase carbon prepared under the same conditions, and its capacitance retention was significantly improved when it was used as an electrode material for EDLCs. G-MCMB-T had a high degree of graphitization (0.895) and when it was used as an electrode material for LIBs it had a high specific capacity of 353.5 mAh g−1 after 100 cycles at 100 mA g−1. This work reports a new preparation method for MCMBs, which could be used to prepare energy storage materials.
Se with Se-C bonds encapsulated in a honeycomb 3D porous carbon as an excellent performance cathode for Li-Se batteries
XIA Zhi-gang, ZHANG Jing-jing, FAN Mei-qiang, LV Chun-ju, CHEN Zhi, LI Chao
2023, 38(1): 190-199.   doi: 10.1016/S1872-5805(22)60596-1
Abstract(219) HTML(121) PDF(87)
Li-Se batteries have risen to prominence as promising lithium-ion batteries thanks to their ultrahigh volumetric energy density and the high electrical conductivity of Se. However, the use of Li-Se batteries is limited not only by the large volume expansion and dissolution of polyselenides in the cathodes during cycling, but also the low selenium loading. A highly effective and currently feasible approach to simultaneously tackle these problems is to position the selenium in a carbon matrix with a sufficient pore volume to accommodate the expansion while increasing the interfacial interaction between the selenium and carbon. We have synthesized a novel cathode material (Se@HPC) for Li-Se batteries of a honeycomb 3D porous carbon derived from a tartrate salt, that was impregnated with Se to produce Se-C bonds. The pore volume of the honeycomb 3D porous carbon was as high as 1.794 cm3 g−1, which allowed 65 wt% selenium to be uniformly encapsulated. Moreover, the strong chemical bonds between selenium and carbon stabilize the selenium, thus inhibiting its huge volume expansion and the dissolution of polyselenides, and promoting charge transfer during cycling. As expected, a Se@HCP cathode has excellent cyclability and a good rate performance. After 200 cycles at 0.2 C, its specific capacity remains at 561 mA h g−1, 83% of the theoretical value, and decays by only 0.058% per cycle. It also has a large capacity of 472.8 mA h g−1 under a high current density of 5 C.
A carbon catalyst doped with Co and N derived from the metal-organic framework hybrid (ZIF-8@ZIF-67) for efficient oxygen reduction reaction
ZHANG Ya-ting, LI Si-yi, ZHANG Na-na, LIN Gang, WANG Rui-qi, YANG Meng-nan, LI Ke-ke
2023, 38(1): 200-210.   doi: 10.1016/S1872-5805(22)60609-7
Abstract(632) HTML(344) PDF(151)
Carbon-based catalysts for the oxygen reduction reaction (ORR) are considered potential substitutes for the expensive platinum-based catalysts. Recently, transition metal and nitrogen co-doped carbon materials (M-N-C) have attracted much attention from researchers due to their low cost and excellent activity. A cobalt- and nitrogen-co-doped porous carbon material (Co-N@CNT-C800) was prepared by the simple one-step pyrolysis of a star fruit-like MOF hybrid (ZIF-8@ZIF-67) at 800 °C. It consisted of CNTs with substantial Co and N co-doping and had a large surface area (428 m2·g−1). It had an excellent half-wave potential and good current density in alkaline media in the ORR with values of 0.841 V and 5.07 mA·cm−2, respectively. Compared with commercial Pt/C materials it also had excellent electrochemical stability and methanol tolerance. This research provides an effective way to fabricate low cost, high activity electrocatalysts for use in energy conversion.
Research progress on electrode materials and electrolytes for supercapacitors
JIAO Chen, ZHANG Wei-ke, SU Fang-yuan, YANG Hong-yan, LIU Rui-xiang, CHEN Cheng-meng
2017, 32(2): 106-115.  
Abstract(1403) PDF(3385)
Influence of graphene oxide additions on the microstructure and mechanical strength of cement
WANG Qin, WANG Jian, LU Chun-xiang, LIU Bo-wei, ZHANG Kun, LI Chong-zhi
2015, 30(4): 349-356.   doi: 10.1016/S1872-5805(15)60194-9
Abstract(896) PDF(509)
研究了不同掺量下氧化石墨烯(GO)对水泥石以及胶砂微观结构和力学性能的影响。含16.5%水的水泥浆、0.05%GO及3倍于水泥的沙子共混物作为添加剂制备成砂浆。通过SEM、液氮吸附仪和一系列标准实验分别对水泥石的微观形态、孔隙结构、抗压抗折强度以及水泥净浆的流动度、黏度、凝结时间进行表征;考察不同GO掺量下水泥水化放热的变化情况。结果表明:GO对水泥浆有显著增稠和促凝作用;GO的掺入可以有效降低水泥的水化放热量;GO对水泥石有显著的增强增韧效果,28天龄期时,GO质量分数为0.05%的水泥石,3、7和28 d抗压强度和抗折强度同比对照组分别增加52.4%、46.5%、40.4%和86.1%、68.5%、90.5%,胶砂的抗压强度和抗折强度同比对照组分别增加43.2%、33%、24.4%和69.4%、106.4%、70.5%;GO在水泥硬化过程中对水泥石中晶体产物的产生有促进作用并能规整晶体的排布而形成针状晶体簇,改善水泥石中的孔结构,降低水泥石中微孔的体积,增加水泥石的密实度,对水泥石有显著地增强增韧效果。
Advances in the ablation resistance of C/C composites
FU Qian-gang, ZHANG Jia-ping, LI He-jun
2015, 30(2): 97-105.  
Abstract(1227) PDF(1345)
C/C复合材料因优异的高温性能被认为是高温结构件的理想材料。然而,C/C复合材料在高温高速粒子冲刷环境下的氧化烧蚀问题严重制约其应用。因此,如何提高C/C复合材料的抗烧蚀性能显得尤为重要。笔者综述C/C复合材料抗烧蚀的研究现状。目前,提高C/C复合材料抗烧蚀性能的途径主要集中于优化炭纤维预制体结构、控制热解炭织构、基体中陶瓷掺杂改性和表面涂覆抗烧蚀涂层等4种方法。主要介绍以上4种方法的研究现状,重点介绍基体改性和抗烧蚀涂层的最新研究进展。其中,涂层和基体改性是提高C/C复合材料抗烧蚀性能的两种有效方法。未来C/C 复合材料抗烧蚀研究的潜在方向主要集中于降低制造成本、控制热解炭织构、优化掺杂的陶瓷相以及将基体改性和涂层技术相结合。
A review of the control of pore texture of phosphoric acid-activated carbons
ZUO Song-lin
2018, 33(4): 289-302.  
Abstract(983) PDF(711)
A review of carbon-carbon composites for engineering applications
SU Jun-ming, ZHOU Shao-jian, LI Rui-zhen, XIAO Zhi-chao, CUI Hong
2015, 30(2): 106-114.  
Abstract(1426) PDF(1283)
评价了中国40多年来在航天、航空、光伏、粉末冶金、工业高温炉领域成功应用的针刺C/C,正交3D C/C、径编C/C、穿刺C/C、轴编C/C等五类C/C复合材料的物理、力学、热学、烧蚀、摩擦磨损、使用寿命等性能及特点,并与其他国家相应材料性能进行分析对比,为建立工程应用C/C复合材料共享的数据库平台奠定基础。揭示了炭纤维预制体、炭基体类型、界面结合状态与材料性能的关联度。指出炭纤维预制体结构单元精细化研究和其结构的梯度设计,以及炭基体的优化组合匹配技术,仍是C/C复合材料性能稳定化提升的重点研究方向。
Preparation and properties of reduced graphene oxide/polyimide composites produced by in-situ polymerization and solution blending methods
MA Lang, WANG Guo-jian, DAI Jin-feng
2016, 31(2): 129-134.  
Abstract(1035) PDF(1406)
利用化学氧化还原法制备出石墨烯。通过原位聚合法及溶液混合法制备出石墨烯/聚酰亚胺复合材料,考察不同复合材料制备方法对其机械性能及导电性能的影响,并对其作用机理进行探讨。结果表明,制备的石墨烯为二维的单层或寡层材料,加入到聚酰亚胺中能够增强其机械性能及电导率。相比溶液混合法,采用原位聚合法时石墨烯在聚酰亚胺基体中分散更均匀,对其团聚作用有更好的抑制作用,制备的复合材料性能更优异。采用该法加入石墨烯的量为1.0 wt%时,拉伸强度达到了132.5 MPa,提高了68.8%;加入量增加到3.0 wt%时,电导率达6.87×10-4S·m-1,提高了8个数量级,对聚酰亚胺的性能有显著的增强作用。
Rheological behavior of fresh cement pastes with a graphene oxide additive
WANG Qin, WANG Jian, LU Chun-xiang, CUI Xin-you, LI Shi-yu, WANG Xi
2016, 31(6): 574-584.   doi: 10.1016/S1872-5805(16)60033-1
Abstract(781) PDF(784)
Hydrothermal synthesis of porous phosphorus-doped carbon nanotubes and their use in the oxygen reduction reaction and lithium-sulfur batteries
GUO Meng-qing, HUANG Jia-qi, KONG Xiang-yi, PENG Hong-jie, SHUI Han, QIAN Fang-yuan, ZHU Lin, ZHU Wan-cheng, ZHANG Qiang
2016, 31(3): 352-362.  
Abstract(832) PDF(711)
碳纳米管优异的物理性质和可调的化学组成使其拥有广泛的应用前景。采用低温过程在碳骨架中引入磷原子预期带来可调的化学特性。本研究采用170℃下水热处理碳纳米管-磷酸混合物获得磷掺杂的碳纳米管。磷掺杂的碳管的磷含量为1.66%,比表面积为132 m2/g,热失重峰在纯氧环境下提升至694℃。当掺磷碳纳米管用于氧还原反应时,其起始电位为-0.20 V,电子转移数为2.60,反应电流显著高于无掺杂的碳纳米管。当其用作锂硫电池正极导电材料时,电极的起始容量为1106 mAh/g,电流密度从0.1 C提升至1 C时容量保留率为80%,100次循环的衰减率为每圈0.25%。
Research progress and potential applications for graphene/polymer composites
ZENG You, WANG Han, CHENG Hui-ming
2016, 31(6): 555-567.  
Abstract(883) PDF(1636)
The effect of nitrogen and/or boron doping on the electrochemical performance of non-caking coal-derived activated carbons for use as supercapacitor electrodes
LU Qian, XU Yuan-yuan, MU Sha-jiang, LI Wen-cui
2017, 32(5): 442-450.   doi: 10.1016/S1872-5805(17)60133-1
Abstract(415) PDF(495)
以新疆不粘煤为原料,三聚氰胺为氮源,硼酸为硼源,通过球磨和后续活化过程合成硼,氮掺杂及硼氮共掺杂煤基活性炭。氮吸附结果显示杂原子掺杂可提高活性炭中介孔的含量。红外和X光电子能谱结果显示,硼、氮原子存在于炭骨架中。循环伏安,恒流充放电及电化学阻抗分析说明硼、氮掺杂活性炭的电化学性能优于非掺杂活性炭。其中,硼氮共掺杂活性炭具有176 F·g-1的高比容量。循环20 000次容量保持率为96%。共掺杂活性炭优异的电化学性能归因于硼氮的协同作用。
Recent progress in the preparation of ordered mesoporous carbons using a self-assembled soft template
HUANG Zheng-hong
2012, 27(05): 321-336.  
Abstract(1924) PDF(28)
The preparation of self-assembled ordered mesoporous carbons (SA-OMCs) using a soft template method has many advantages, such as low cost, ease of preparation and control. This paper review the development periods, the basic principles and preparation procedures with an emphasis on the control of morphology and multi-level pore structure of OMCs based on SA-OMCs. And suggest that further research in this area can be focused on expanding the scope of the precursor, improving the flexibility and conductivity of the shaped products, such as fibers and membranes.
Preparation of graphene by chemical vapor deposition
REN Wen-cai, GAO Li-bo, MA Lai-peng, CHENG Hui-ming
2011, 26(01): 71-80.  
Abstract(2907) PDF(245)
Chemical vapor deposition (CVD) is an effective way for the preparation of graphene with large area and high quality. In this review, the mechanism and characteristics of the four main preparation methods of graphene are briefly introduced, including micromechanical cleavage, chemical exfoliation, SiC epitaxial growth and CVD. The recent advances in the CVD growth of graphene and the related transfer techniques in terms of structure control, quality improvement and large area graphene synthesis were discussed. Other possible methods for the CVD growth of graphene were analyzed including the synthesis and nondestructive transfer of large area single crystalline graphene, graphene nanoribbons and graphene macrostructures.