Recent Progress on Molybdenum Carbide-Based Catalysts for Hydrogen Evolution: A Review

Abstract

Hydrogen is an ideal alternative energy for fossil fuels to solve aggravating environmental and energy problems. Electrocatalytic hydrogen evolution reaction (HER) driven by renewable electricity (sunlight, wind, tide, etc.) is considered to be one of the most promising approaches for hydrogen production. However, its large-scale applications are greatly limited by the use of noble platinum (Pt) group electrocatalysts. As an earth-abundant/non-noble HER catalyst, molybdenum carbide (MoxC: MoC or Mo2C) has attracted extensive attention in the field of sustainable hydrogen production due to its excellent Pt-like catalytic activity, low cost, high chemical stability, and natural abundance. In this review, the progress on the strategies for optimizing the catalytic activity of MoxC is summarized, including optimization of synthesis methods, composites with carbon material, non-precious metal doping, transition metal doping, construction of the heterogeneous structure, etc. Among them, the importance of sulphur-doping, Ni-doping, and heterophase structure on molybdenum carbide-based catalysts for enhancement of HER activity has been highlighted. In addition, molybdenum carbide-based bi-functional catalysts are presented for the application in full water splitting. Finally, several effective strategies for molybdenum carbide-based catalyst design are concluded, and challenges remained in electrocatalytic water splitting are raised. Future development trends and perspectives for this promising material are also discussed.

Implication of surface oxidation of nanoscale molybdenum carbide on electrocatalytic activity

“…Early transition metal carbides (TMCs) are promising substitutes for heterogeneous noble metal catalysts in water splitting, 1–3 nitrogen reduction, 4,5 and biomass conversion, 6,7 as well as in more traditional petrochemical processes such as isomerization, deoxygenation, and hydrogenation. Their platinum-like catalytic properties stem from the interstitial insertion of carbon atoms into the lattice of transition metals, which leads to orbital hybridization and brings about the d-band electronic density of states at the Fermi level resembling noble metals.…”