High‐Flux Carbon Molecular Sieve Membranes for Gas Separation

Carbon membranes have great potential for highly selective and cost‐efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp² hybridized carbon sheets as well as sp³ hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m³(STP)/(m²hbar). Furthermore, by a post‐synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide.     

氮掺杂石墨烯量子点/MOF衍生多孔碳纳米片构筑高性能超级电容器

首先采用溶液法在碳布上生长Co-MOF二维纳米片,通过高温退火和刻蚀后得到MOF衍生多孔碳纳米片。以Co-MOF衍生的多孔碳纳米片/碳布(CNS/CC)作为碳基骨架,采用电化学沉积法负载高活性氮掺杂石墨烯量子点(N-GQDs),制备得到分级多孔结构的N-GQD/CNS/CC复合材料。组装成自支撑且无粘结剂的N-GQD/CNS/CC电极,当电流密度为1 A·g~(-1)时,其比电容高达423 F·g~(-1)。通过储能机制和电容贡献机制的研究表明,在碳纤维上原位生长的具有高双电层电容的CNS和表面负载具有高赝电容的N-GQDs之间相互协同作用,使得N-GQD/CNS/CC电极具有高电容性能,是一种理想的超级电容器电极材料。电极材料的高导电、分级多孔结构有利于电子的传输和电解质离子的扩散,具有良好的动力学性能,能快速充放电和具有优异的倍率特性。将电极组装成对称型超级电容器,功率密度为250 W·kg~(-1)时对应的能量密度达到7.9 Wh·kg~(-1),且经过10 000次循环后电容保持率为91.2%,说明氮掺杂石墨烯量子点/MOF衍生多孔碳纳米片复合材料是一种电化学性能稳定的具有高电容性能的全碳电极材料。     

High-Flux Carbon Molecular Sieve Membranes for Gas Separation

Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp² hybridized carbon sheets as well as sp³ hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m³(STP)/(m²hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide.     

锂离子电池正极材料LiFePO4/ C的合成研究

以三价铁化合物作为铁源，采用碳热还原法一步合成得到锂离子电池正极材料LiFePO₄。利用X射线衍射仪、扫描电镜、碳硫分析法和电化学性能测试方法对磷酸铁锂材料的物相结构、表面形貌、含碳量(质量分数)以及电性能进行分析研究。讨论了烧结温度、烧结时间和掺碳量对材料电性能的影响。结果表明，LiFePO₄的电性能与烧结温度、时间以及掺碳量有密切的关系，在优化试验条件下制备的正极材料LiFePO₄，以电流密度为17 mA·g^-1充放电，首次放电容量达到141.8 mAh·g^-1，80次循环后放电容量为137.7 mAh·g^-1，容量保持率为97.1%。     

Highly Dispersible Hexagonal Carbon–MoS2–Carbon Nanoplates with Hollow Sandwich Structures for Supercapacitors

MoS₂, a typical layered transition-metal dichalcogenide, is promising as an electrode material in supercapacitors. However, its low electrical conductivity could lead to limited capacitance if applied in electrochemical devices. Herein, a new nanostructure composed of hollow carbon–MoS₂–carbon was successfully synthesized through an l -cysteine-assisted hydrothermal method by using gibbsite as a template and polydopamine as a carbon precursor. After calcination and etching of the gibbsite template, uniform hollow platelets, which were made of a sandwich-like assembly of partial graphitic carbon and two-dimensional layered MoS₂ flakes, were obtained. The platelets showed excellent dispersibility and stability in water, and good electrical conductivity due to carbon provided by the calcination of polydopamine coatings. The hollow nanoplate morphology of the material provided a high specific surface area of 543 m² g⁻¹, a total pore volume of 0.677 cm³ g⁻¹, and fairly small mesopores (≈5.3 nm). The material was applied in a symmetric supercapacitor and exhibited a specific capacitance of 248 F g⁻¹ (0.12 F cm⁻²) at a constant current density of 0.1 A g⁻¹; thus suggesting that hollow carbon–MoS₂–carbon nanoplates are promising candidate materials for supercapacitors.     

The reduction of carbonyl compounds at carbon electrodes in acidic water/methanol mixtures

The voltammetry of benzaldehyde in acidic methanol/water mixtures is shown to depend strongly on the cathode material. At pH 1, benzaldehyde always reduces in two le⁻ steps and the first step is always reversible. On the other hand, the potential for the second reduction step varies strongly with cathode material; at vitreous carbon, the second step occurs at much more negative potential than at lead or mercury, giving much better resolution of the two reduction waves. In citrate buffer, pH 4, the first reduction step is shifted negative; as a result, at lead a single 2e⁻ wave is seen but at vitreous carbon, two 1e⁻ steps are still observed. These changes in voltammetry with cathode material are shown to be general for both aldehydes and ketones.     

A porous carbon material prepared by template synthesis using Aerosil

Synthesis of a porous carbon material using Aerosil as template is suggested. The material obtained has high specific surface area (2800 m² g^?1) and high limiting sorption volume (6.2 cm³ g^?1). The porous carbon material prepared by this procedure can be used in solid-phase extraction of organic toxicants from aqueous solutions.     

A novel biocompatible drug carrier for oral delivery and controlled release of antibiotic drug: loading and release of clarithromycin as an antibiotic drug model

In this work, a novel biocompatible carrier was designed by modification of nanoporous carbon material and synthesized by hydrothermal condensation of d-Fructose, as the carbon source, in the presence of Pluronic^® F127, as the surfactant. The prepared material is completely biocompatible and suitable for oral drug delivery. As this nanoporous carbon has surface decorated hydroxyl groups, they are able to react with 3-aminopropyltriethoxysilane agent and produce amino-functionalized nanoporous carbon. The synthesis of amine-modified carbon nanoporous material was confirmed by X-ray powder diffraction, IR spectroscopy, elemental analysis, thermal analysis and nitrogen adsorption analysis. Clarithromycin as an active drug molecule with carbonyl and hydroxyl functional groups in chemical structure was chosen as the drug model and stored in pores of the amine-modified nanoporous carbon. Release of clarithromycin from modified nanoporous carbon was investigated in mouth and stomach pH values. The results showed that this drug carrier can transfer the drug up to stomach without any leak or release. The release time was investigated, and the results showed that the carrier is also successful for the controlled-release delivery.     

Scalable Dry Production Process of a Superior 3D Net‐Like Carbon‐Based Iron Oxide Anode Material for Lithium‐Ion Batteries

Carbon‐based transition‐metal oxides are considered as an appropriate anode material candidate for lithium‐ion batteries. Herein, a simple and scalable dry production process is developed to produce carbon‐encapsulated 3D net‐like FeO_x /C materials. The process is simply associated with the pyrolysis of a solid carbon source, such as filter paper, adsorbed with ferrite nitrate. The carbon derived from filter paper induces a carbothermal reduction to form metallic Fe, the addition of carbon and iron increase the conductivity of this material. As expected, this 3D net‐like FeO_x /C composite delivers an excellent charge capacity of 851.3 mAh g⁻¹ after 50 cycles at 0.2 A g⁻¹ as well as high stability and rate performance of 714.7 mAh g⁻¹ after 300 cycles at 1 A g⁻¹. Superior performance, harmlessness, low costs, and high yield may greatly stimulate the practical application of the products as anode materials in lithium‐ion batteries.     

锂硫电池正极用硫/介孔碳复合材料的制备及电化学性能

制备了以十二烷基硫酸钠(SDS)为模板的介孔碳,并将介孔碳和单质硫采用熔融渗透法复合制得硫/介孔碳复合材料。SEM、TEM和BET结果显示介孔碳成直径约为500 nm的大小均一的球体,存在孔径为2 nm的微孔;单质硫充分填充在介孔碳的微孔中。以硫/介孔碳复合物作为锂硫电池正极材料时显示出高的电化学性能。初始放电容量高达1519 mAh·g^-1,在200 mA·g^-1的电流密度下充放电200个循环后依然能保持在835 mAh·g^-1。硫/介孔碳复合材料的高倍率性能和优异的循环稳定性,源于介孔碳良好的导电性及其孔结构的固硫作用。     

New ferromagnetic mesh electrode material for electroanalytical applications

A new, advanced, ferromagnetic carbon material (Fe@C NPs–GC 3D porous mesh) has been developed. The application of this electrode material has led to an increase in the voltammetric current density of paramagnetic species, such as FcTMA⁺, Fc-FcTMA⁺, on the application of a 140 mT magnetic field, compared with a glassy carbon electrode modified with a layer of Fe@C NPs alone. The functionality of the developed material was tested with two biologically important paramagnetic species: hemoglobin and dioxygen.     

Bioelectrocatalytic Oxygen Reduction by Laccase Immobilized on Various Carbon Carriers

Laccase is an enzyme that is used for fabricating cathodes of biofuel cells. Many studies have been aimed at searching the ways for enhancing specific electrochemical characteristics of cathode with the laccase- based catalyst. The electroreduction of oxygen on the electrode with immobilized laccase proceeds under the conditions of direct electron transfer between the electrode and active enzyme center. In this work, the effect of oxygen partial pressure on the electrocatalytic activity of laccase is studied. It is shown that, at the concentrations of oxygen dissolved in the electrolyte higher than 0.28 mM, the process is controlled by the kinetics of the formation of laccase–oxygen complex, whereas at lower concentrations and a polarization higher than 0.3 V, the process is limited by the oxygen diffusion. A wide range of carbon materials are studied as the carriers for laccase immobilization: carbon black and nanotubes with various BET specific surface areas. The conditions, which provide the highest surface coverage of carbon material with enzyme in the course of spontaneous adsorptive immobilization and the highest specific characteristics when using a “floating” electrode simulating a gas-diffusion electrode, are determined: 0.2 M phosphate-acetate buffer solution; oxygen atmosphere; the carrier material (nanotubes with a BET surface area of 210 m²/g and a mesopore volume of 3.8 cm³/g); and the composition of active mass on the electrode (50 wt % of carbon material + 50 wt % of hydrophobized carbon black).     

A 3D Organically Synthesized Porous Carbon Material for Lithium‐Ion Batteries

We report the first organically synthesized sp–sp³ hybridized porous carbon, OSPC‐1. This new carbon shows electron conductivity, high porosity, the highest uptake of lithium ions of any carbon material to‐date, and the ability to inhibit dangerous lithium dendrite formation. The new carbon exhibits exceptional potential as anode material for lithium‐ion batteries (LIBs) with high capacity, excellent rate capability, long cycle life, and potential for improved safety performance.     

百香果皮基原位氮掺杂多孔碳/硫复合正极的制备及储锂性能

以生物质百香果皮为碳源,KHCO3为活化剂,采用同步活化碳化方法制备原位氮掺杂的分级多孔碳材料,将其与单质硫复合制得多孔碳/硫正极材料。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征技术对制备材料的物相组成、微观形貌、比表面积及孔结构进行研究分析。同时,利用紫外可见吸收光谱研究了多孔碳对多硫化物的吸附作用,用恒电流充放电测试了不同硫含量(60%～80%)的多孔碳/硫复合正极材料的电化学性能。结果表明,制得的多孔碳材料为无定型,具有1 093 m²·g^-1的高比表面积和0.63 cm³·g^-1的孔容;丰富的多孔结构和原位氮掺杂对多硫化物的物理化学协同吸附作用,有效降低了锂硫电池的“穿梭效应”,提高了电池的放电比容量和循环性能。硫含量为60%的多孔碳/硫复合材料,在0.05C和0.2C倍率下可释放1 057.7和763.4 mAh·g^-1的高初始放电比容量,在1C的高倍率下循环300次后的保持率为75%。     

Ultrastable Surface-Dominated Pseudocapacitive Potassium Storage Enabled by Edge-Enriched N-Doped Porous Carbon Nanosheets

The development of ultrastable carbon materials for potassium storage poses key limitations caused by the huge volume variation and sluggish kinetics. Nitrogen-enriched porous carbons have recently emerged as promising candidates for this application; however, rational control over nitrogen doping is needed to further suppress the long-term capacity fading. Here we propose a strategy based on pyrolysis–etching of a pyridine-coordinated polymer for deliberate manipulation of edge-nitrogen doping and specific spatial distribution in amorphous high-surface-area carbons; the obtained material shows an edge-nitrogen content of up to 9.34 at %, richer N distribution inside the material, and high surface area of 616 m² g⁻¹ under a cost-effective low-temperature carbonization. The optimized carbon delivers unprecedented K-storage stability over 6000 cycles with negligible capacity decay (252 mA h g⁻¹ after 4 months at 1 A g⁻¹), rarely reported for potassium storage.     

Electrodeposition of chitosan enables synthesis of copper/carbon composites for H2O2 sensing

This work presents a novel approach in synthesizing copper (Cu)/carbon composite materials by electrodeposition of the biopolymer chitosan, a renewable carbon precursor, on a copper anode, followed by pyrolysis of the electrodeposited chitosan gel. The amount of copper in the Cu/carbon composite material can be controlled by modifying the pH of the chitosan solution from which the electrodeposition is performed. This further influences the physical properties of the composite material. Here we show a 14 fold increase in electrical conductivity of the Cu/carbon composite, when compared to the material without copper inclusions. Metal/carbon composite materials have a wide range of applications already reported in the literature. As a proof of concept, we demonstrate the electrochemical sensing capability of this Cu/carbon material for non-enzymatic detection of hydrogen peroxide, achieving a sensitivity of 58.9 μA/mM cm², which is comparable to state of the art non-enzymatic hydrogen peroxide sensors. The anodic electrodeposition of chitosan proves to be a simple and straightforward medium for synthesis of Cu/carbon composites. We speculate that this method can be extended to obtain other metal/carbon composites as a low-cost alternative for the fabrication of functional composite electrodes.     

Graphene/Amorphous Carbon Restriction Structure for Stable and Long-Lifespan Antimony Anode in Potassium-Ion Batteries

Sb-based materials have attracted much attention owing to their ability to undergo a multi-electron alloy reaction with K⁺. However, there are still the serious problems of volume change and aggregation of particles, which lead to rapid capacity fading and a limited lifespan. In this work, a graphene/amorphous carbon restriction structure is proposed, in which the amorphous carbon layer on the surface of Sb nanoparticles can protect the particles from pulverization, and the graphene can buffer the volume change of the material. In addition, the conductive network formed by the dual carbon structure effectively improves the rate performance of the material. Thus, the material delivers a high capacity of 550 mA h g⁻¹ at 100 mA g⁻¹, a rate capability of 370 mA h g⁻¹ at 2000 mA g⁻¹, and a long lifespan of 350 cycles without significant capacity fading. The dual carbon strategy proposed offers a reference for the design of high-performance anode materials.     

Electrochemical kinetics of nanostructure LiFePO4/graphitic carbon electrodes

Lithium cation insertion/deinsertion reaction kinetics in a LiFePO₄ (LFP)/graphitic carbon composite material were electrochemically studied with a cavity microelectrode (CME). The LFP/graphitic carbon composite has a core LFP (crystalline/amorphous)/graphitic carbon shell structure. In the crystalline and amorphous LFP phase, different reaction mechanisms were observed and characterized. While the reaction mechanism in the crystalline LFP phase is controlled by Li⁺ diffusion, the amorphous LFP phase shows a fast, surface-controlled, pseudocapacitive charge-storage mechanism. This pseudocapacitive behavior is extrinsic in origin since it comes from the presence of Fe^3 + defects in the structure. These features explain the ultrafast performance of the material which offers interesting opportunities as a positive electrode for assembling high power and high energy hybrid supercapacitors.     

Synthesis of Hierarchically Porous Sandwich‐Like Carbon Materials for High‐Performance Supercapacitors

For the first time, hierarchically porous carbon materials with a sandwich‐like structure are synthesized through a facile and efficient tri‐template approach. The hierarchically porous microstructures consist of abundant macropores and numerous micropores embedded into the crosslinked mesoporous walls. As a result, the obtained carbon material with a unique sandwich‐like structure has a relatively high specific surface (1235 m² g^?1), large pore volume (1.30 cm³ g^?1), and appropriate pore size distribution. These merits lead to a comparably high specific capacitance of 274.8 F g^?1 at 0.2 A g^?1 and satisfying rate performance (87.7 % retention from 1 to 20 A g^?1). More importantly, the symmetric supercapacitor with two identical as‐prepared carbon samples shows a superior energy density of 18.47 Wh kg^?1 at a power density of 179.9 W kg^?1. The asymmetric supercapacitor based on as‐obtained carbon sample and its composite with manganese dioxide (MnO₂) can reach up to an energy density of 25.93 Wh kg^?1 at a power density of 199.9 W kg^?1. Therefore, these unique carbon material open a promising prospect for future development and utilization in the field of energy storage.     

硫/水热碳球复合材料的制备及对锂硫电池倍率性能的影响

在锂硫电池正极材料的研究中,碳材料可以有效改善电池倍率及循环性能.为了提高锂硫电池的高倍率放电性能,通过水热合成的方法,制备了由非均匀粒径碳球组成的碳材料.与硫热合成后,硫均匀分布在碳材料表面及周围,复合材料含硫量为52wt%.0.2C放电电流下,首次放电比容量为1174mAh·g^-1,100次循环后放电比容量为788mAh·g^-1.在4C的放电电流下,放电比容量稳定维持在600mAh·g^-1,循环过程中,库伦效率高于90%.该碳材料有良好的导电网络,且制备方便,成本低廉,对于穿梭效应和放电过程中的膨胀效应有一定的抑制作用,是一种优秀的正极材料.