New Carbon Materials最新文献

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.

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.

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.

The reduction of carbon dioxide (CO₂) by electrochemical methods for the production of fuels and value-added chemicals is an effective strategy for overcoming the global warming problem. Due to the stable molecular structure of CO₂, the design of highly selective, energy-efficient and cost-effective electrocatalysts is key. For this reason, graphene and its derivatives are competitive for CO₂ electroreduction with their unique and excellent physical, mechanical and electrical properties and relatively low cost. In addition, the surface of graphene-based materials can be modified using different methods, including doping, defect engineering, production of composite structures and wrapped shapes. We first review the fundamental concepts and criteria for evaluating electrochemical CO₂ reduction, as well as the catalytic principles and processes. Methods for preparing graphene-based catalysts are briefly introduced, and recent research on them is summarized according to the categories of the catalytic sites. Finally, the future development direction of CO₂ electroreduction technology is discussed.

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 (Y_NH3) 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.

Molybdenum selenide (MoSe₂) has been regarded as an advanced electrocatalyst for the hydrogen evolution reaction (HER). However, its electrocatalytic performance is far inferior to platinum (Pt). Combining semiconductors with metals to construct Mott-Schottky heterojunctions has been considered as an effective method to enhance HER activity. In this work, we report a typical Mott-Schottky heterojunction composed of metal Co and semiconductor MoSe₂ on carbon nanotubes (Co/MoSe₂@CNT), prepared by a sol-gel process followed by thermal reduction. The characterization and theoretical calculations show that a Co/MoSe₂ Mott-Schottky heterojunction can cause electron redistribution at the interface and form a built-in electric field, which not only optimizes the free energy of hydrogen atom adsorption, but also improves the charge transfer efficiency during hydrogen evolution. Thus, the Co/MoSe₂@CNT has excellent catalytic activity with a low overpotential of 185 mV at 10 mA cm⁻² and a small Tafel slope of 69 mV dec⁻¹. This work provides a new strategy for constructing Co/MoSe₂ Mott-Schottky heterojunctions and highlights the Mott-Schottky effect, which may inspire the future development of more attractive Mott-Schottky electrocatalysts for H₂ production.

Metal-air batteries have received significant attention as highly efficient energy conversion and storage devices. Nevertheless, several difficulties, such as the sluggish reaction kinetics of the cathode and the high cost of precious metals, have significantly hampered their commercialization. Biomass carbon materials have emerged as an important alternative for the development of high-performance cathode materials in metal-air batteries, owing to their remarkable electrochemical characteristics, environmental friendliness and cost effectiveness. In recent years, there has been huge progress in the preparation and design of biomass carbon materials. This review summarizes the most recent research on these materials, and the effects of the reaction mechanism, synthesis method and multidimensional (1D, 2D, 3D) structure on their electrocatalytic performance are reviewed. Finally, problems associated with their use and possible new developments are discussed. The review presents new perspectives on the structure of these materials, and provides a basis for the development of efficient, affordable, and stable cathode materials for metal-air batteries.

A commercial polypropylene (PP) separator was modified by a one-dimensional carbon nanotube (CNT) and two-dimensional montmorillonite (MMT) hybrid material (CNT-MMT). Because of the high electron conductivity of the CNTs, and the strong polysulfide (LiPS) adsorption ability and easy lithium ion transport through MMT, the interconnected porous CNT-MMT interlayer with excellent structural integrity strongly suppresses LiPS shuttling while maintaining high lithium-ion transport, producing a high utilization of the active sulfur. Lithium-sulfur batteries assembled with this interlayer have a high lithium-ion diffusion coefficient, a high discharge capacity and stable cycling performance. They had an initial specific capacity of 1 373 mAh g⁻¹ at 0.1 C, and a stable cycling performance with a low decay rate of 0.062% per cycle at 1 C after 500 cycles.

Because of their high electrochemical activity, good structural stability, and abundant active sites, multi-metal sulfide/carbon (MMS/C) composites are of tremendous interest in diverse fields, including catalysis, energy, sensing, and environmental science. However, their cumbersome, inefficient, and environmentally unfriendly synthesis is hindering their practical application. We report a straightforward and universal method for their production which is based on homogeneous multi-phase interface engineering. The method has enabled the production of 14 different MMS/C composites, as examples, with well-organized composite structures, different components, and dense heterointerfaces. Because of their composition and structure, a typical composite has efficient, fast, and persistent lithium-ion storage. A ZnS-Co₉S₈/C composite anode showed a remarkable rate performance and an excellent capacity of 651 mAh·g⁻¹ at 0.1 A·g⁻¹ after 600 cycles. This work is expected to pave the way for the easy fabrication of MMS/C composites.

Carbon/carbon-silicon carbide (C/C-SiC) composites were prepared by impregnation, hot-pressing with curing, carbonization at 800 ^oC and high-temperature heat treatment (800-1600 ^oC) using a 2D laminated carbon cloth as the reinforcing filler, and furfurone resin mixed with silicon, carbon from furfurone resin and SiC powders as the matrix. The effects of the addition of the three powders as well as subsequent chemical vapor infiltration (CVI) by methane on the density, microstructure and bend strength of the composites were investigated by scanning electron microscopy, density measurements, X-ray diffraction and mechanical testing. Both the SiC powders formed by the reaction at 1 600 ^oC between the added Si and C particles and the added SiC powder, play a role in the reinforcement of the materials. In three-point bending, the composites had a pseudoplastic fracture mode and showed interlaminar cracking. After 10 h CVI with methane, pyrolytic carbon was formed at the interface between some of the carbon fibers and the resin carbon matrix, which produced maximum increases in the density and flexural strength of the composites of 4.98% and 38.86%, respectively.