Recent advances in defect-engineered molybdenum sulfides for catalytic applications.

Electrochemical energy conversion and storage driven by renewable energy sources is drawing ever-increasing interest owing to the needs of sustainable development. Progress in the related electrochemical reactions relies on highly active and cost-effective catalysts to accelerate the sluggish kinetics. A substantial number of catalysts have been exploited recently, thanks to the advances in materials science and engineering. In particular, molybdenum sulfide (MoS x ) furnishes a classic platform for studying catalytic mechanisms, improving catalytic performance and developing novel catalytic reactions. Herein, the recent theoretical and experimental progress of defective MoS x for catalytic applications is reviewed. This article begins with a brief description of the structure and basic catalytic applications of MoS 2 . The employment of defective two-dimensional and non-two-dimensional MoS x catalysts in the hydrogen evolution reaction (HER) is then reviewed, with a focus on the combination of theoretical and experimental tools for the rational design of defects and understanding of the reaction mechanisms. Afterward, the applications of defective MoS x as catalysts for the N 2 reduction reaction, the CO 2 reduction reaction, metal-sulfur batteries, metal-oxygen/air batteries, and the industrial hydrodesulfurization reaction are discussed, with a special emphasis on the synergy of multiple defects in achieving performance breakthroughs. Finally, the perspectives on the challenges and opportunities of defective MoS x for catalysis are presented.