Recent developments in transition metal carbides and nitrides as hydrogen evolution electrocatalysts

High-performance electrode materials are the key to advances in the areas of energy conversion and storage (e.g., fuel cells and batteries). In this Review, recent progress in the synthesis and electrochemical application of transition metal carbides (TMCs) and nitrides (TMNs) for energy storage and conversion is summarized. Their electrochemical properties in Li-ion and Na-ion batteries as well as in supercapacitors, and electrocatalytic reactions (oxygen evolution and reduction reactions, and hydrogen evolution reaction) are discussed in association with their crystal structure/morphology/composition. Advantages and benefits of nanostructuring (e.g., 2D MXenes) are highlighted. Prospects of future research trends in rational design of high-performance TMCs and TMNs electrodes are provided at the end.

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Transition Metal Carbides and Nitrides in Energy Storage and Conversion

Hydrogen is an ideal candidate for the replacement of fossil fuels in the future due to zero emission of carbonaceous species during its utilization. Water electrolysis is a dependable link of primary renewable energy and stable hydrogen energy. In this work, the fundamentals of water electrolysis, current popular electrocatalysts developed for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) in liquid electrolyte water electrolysis are reviewed. The main HER catalysts include noble metals, non-noble metals and composites, noble metal-free alloys, metal carbides, chalcogenides, phosphides and metal-free materials while the OER catalysts are focused on efficient Co-based, Ni-based materials and layered double hydroxide (LDH) materials. The strategies to improve catalytic activity, long-term durability and endurance to electrochemical erosion are introduced. The main challenges and future prospects for the further development of electrodes for water electrolysis are discussed. It is expected to give guidance for the development of novel low-cost nanostructured electrocatalysts for electrochemical water splitting.

Nanostructured catalysts for electrochemical water splitting: current state and prospects

A new one-step ion-exchange/activation combination method using a metal-ion exchanged resin as a carbon precursor is used to prepare a ultrahigh surface area and three-dimensional hierarchical porous graphene-like networks for fast and highly stable supercapacitors.

Simultaneous formation of ultrahigh surface area and three-dimensional hierarchical porous graphene-like networks for fast and highly stable supercapacitors.

Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m2/g. Subsequent thermal treatments at elevated temperatures led to the decomposition and evaporation of the FeO(OH) nanocrystals and the formation of mesoporous carbons with the surface area markedly enhanced to 934.8 m2/g. Electrochemical measurements revealed that the resulting mesoporous carbons exhibited apparent electrocatalytic activity for oxygen reduction reactions (ORR), and the one prepared at 800 °C (Fe-N/C-800) was the...

Mesoporous N-Doped Carbons Prepared with Thermally Removable Nanoparticle Templates: An Efficient Electrocatalyst for Oxygen Reduction Reaction

Nanocomposites consisting of the bimetallic carbide Co6Mo6C2 supported on graphitic carbon (gC) were synthesized in situ by an anion-exchange method for the first time. The Co6Mo6C2/gC nanocomposites were not only chemically stable but also electrochemically stable. The catalyst prepared by loading Pt nanoparticles onto Co6Mo6C2/gC was evaluated for the oxygen reduction reaction in acidic solution and showed superior activity and stability in comparison with commercial Pt/C. The higher mass activity of the Pt–Co6Mo6C2/gC catalyst indicated that less Pt would be required for the same performance, which in turn would reduce the cost of the fuel cell electrocatalyst. The method reported here will promote broader interest in the further development of other nanostructured materials for real-world applications.

Bimetallic carbide nanocomposite enhanced Pt catalyst with high activity and stability for the oxygen reduction reaction.

We have developed a general ion-exchange method of preparing a composite of low nanometre size carbide particles with controllable size less than 10 nm on carbon foams. The nanoarchitectures of the carbide nanoparticles on carbon foam are used to load Pt nanoparticles as electrocatalysts which show enhanced activity for the oxygen reduction reaction.

A universal method to synthesize nanoscale carbides as electrocatalyst supports towards oxygen reduction reaction.

The invention discloses a method for one-step localized synthesizing nanometer carbide-a graphitized carbon composite material and a method for loading a nanometer catalyst thereof. The synthetic method comprises: dissolving a metal source in a solvent, then adding a pretreated ion exchange resin; adding the graphitized carbon catalyst, cleaning the ion exchange resin which performs a ion exchange by deionized water and drying; precarbonizating the obtained product; then performing a graphitization heat treatment; crushing the obtained products through the graphitization heat treatment and then pickling, removing the graphitization catalyst, washing, drying to obtain the composite material. The method for loading the nanometer catalyst comprises: placing the composite material in a container and adding a solvent for dispersing by ultrasonic; adding a proper amount of precursor of an active metal for dispersing by ultrasonic with stirring; regulating pH value; using an alternative microwave heat treatment; adjusting pH value, stirring, filtering, drying and grinding to obtain the load type catalyst. The invention has the advantages of simple technology, rapid preparation, safety, environmental protection and easily realizing large scale production.

Method for one-step localized synthesizing nanometer carbide-graphitized carbon composite material and method for loading nanometer catalyst thereof

Graphitic carbon (GC) is prepared using an ion-exchange resin as carbon source at 600 °C. A Co salt is selected as the graphitization catalyst and is pre-exchanged onto the resin during the ion-exchange process. The GC is characterized by transmission electron microscopy, x-ray diffraction, Raman spectroscopy, and thermogravimetry. Analysis of the crystallization shows that graphitization can occur at a temperature of as low as 600 °C, compared to the usual temperature of above 2000 °C in industry and above 1000 °C in literature. Different carbon structures have been found for different pretreatments of the resin and different heat treatment temperatures. This energy-saving method is an important breakthrough for the economic mass production of GC.

Xueming Ma

Papers

Bimetallic carbide nanocomposite enhanced Pt catalyst with high activity and stability for the oxygen reduction reaction.

A universal method to synthesize nanoscale carbides as electrocatalyst supports towards oxygen reduction reaction.

Method for one-step localized synthesizing nanometer carbide-graphitized carbon composite material and method for loading nanometer catalyst thereof

Direct formation of nanostructured graphitic carbon from an acrylic ion-exchange resin at 600°C