Highly efficient tungsten/molybdenum-based electrocatalysts for the oxygen reduction reaction: a review

The oxygen reduction reaction (ORR) is one of the significant catalytic reactions of fuel cells. To date, platinum-based metals are considered the most promising ORR electrocatalysts, but they still have problems such as high price and poor sustainability. Tungsten/molybdenum-based group VIB materials are potential substitutes for Pt thanks to their relatively abundant resources and similar electronic structure to that of Pt. This paper aims to provide a comprehensive understanding and timely reference to recent advances in W/Mo-based group VIB electrocatalysts in the field of the ORR. First of all, we discuss the basic principles of the ORR, the synthesis of W/Mo-based electrocatalysts and performance test methods. Secondly, the synthesis strategy for high-performance W/Mo-based electrocatalysts is discussed. Then, progress in research on W/Mo-based catalysts in recent years is reviewed, focusing on W/Mo-based heteroatom doped, single atom, and compound (carbide, nitride, sulfide, oxide) electrocatalysts. Finally, development prospects and challenges for W/Mo-based electrocatalysts are discussed. The mechanisms, synthesis methods and strategies for application of W/Mo-based ORR electrocatalysts are briefly introduced. Recent advances in W/Mo-based ORR electrocatalysts are discussed in detail.