Mo-modified electronic effect on sub-2 nm Ru catalyst for enhancing hydrogen oxidation catalysis

The development of efficient and durable hydrogen oxidation reaction (HOR) electrocatalysts is desired but challenged before the commercialization of the H-2-O-2 fuel cell system. In this study, ultrafine RuMo bimetallic particles (similar to 1.7 nm) anchored on N, P-co-doped hollow carbon polyhedrons (sub-2 nm RuMo/HC) were designed via two-step pyrolysis. For HOR in 0.1 M KOH, the sub-2 nm RuMo/HC exhibited a high-level mass activity of 3830 mA mg(Ru)(-1), nearly 25-fold and 13-fold those for commercial Ru/C and sub-2 nm Ru/HC, respectively. Such outstanding behaviour could be ascribed to the well-tuned d band structure of Ru with suitable adsorption for the H* intermediate. More importantly, the formation of soluble RuOx species on the catalyst's surface could be effectually suppressed by embedding Mo, and thus the electrochemical durability of sub-2 nm RuMo/HC was increased similar to 70% during the HOR process. This work offers helpful tactics for enhancing the activity and stability in an alkaline electrooxidation system.