Sustainable hydrogen production by molybdenum carbide-based efficient photocatalysts: From properties to mechanism

Hydrogen is considered to be a promising energy carrier to solve the issue of energy crisis. Molybdenum carbide (MoxC) is the typical material, which has similar properties of Pt and thought to be an attractive alternative to noble metals for H-2 evolution. The study of MoxC as alternative catalyst for H-2 production is almost focused on electrocatalytic field, while the application of MoxC as a co-catalyst in photocatalytic H-2 evolution has received in-depth research in recent years. Particularly, MoxC exhibits significant enhancement in the H-2 production performance of semiconductors under visible light irradiation. However, a review discussing MoxC serving as a cocatalysts in the photocatalytic H-2 evolution is still absent. Herein, the recent progress of MoxC on photocatalytic H-2 evolution is reviewed. Firstly, the preparation methods including chemical vapor deposition, temperature programming, and organic-inorganic hybridization are detailly summarized. Then, the fundamental structure, electronic properties, and specific conductance of MoxC are illustrated to illuminate the advantages of MoxC as a co-catalyst for H-2 evolution. Furthermore, the different heterojunctions formed between MoxC and other semiconductors for enhancing the photocatalytic performance are emphasized. Finally, perspectives regarding the current challenges and the future research directions on the improvement of catalytic performance of MoxC-based photocatalysts are also presented. (C) 2020 Elsevier B.V. All rights reserved.