Effect of stoichiometric ratio of rhodium antimonide intermetallic compounds on the performance of electrocatalysis to the hydrogen oxidation reaction and CO-tolerance

Abstract

Binary intermetallic compounds (BIMCs) play a significant role in various catalytic systems. However, the synthesis of BIMCs with different stoichiometric ratios remains challenging, and the corresponding studies toward catalytic performance are scarce. Herein, three kinds of pure-phase rhodium antimonide BIMCs (Rh2Sb, RhSb, and RhSb2) were successfully fabricated. Interestingly, Rh2Sb BIMC shows the highest activity and long-time stability toward hydrogen oxidation reaction (HOR) in alkaline condition among the prepared samples, reaching a mass normalized kinetic current density of 2.04 A mgPGM-1 (PGM: platinum group metal), which is 7.6 times higher than that of commercial Pt/Ccom. However, the CO-tolerance performances under 1000 ppm CO/H2 follows the order: RhSb > Rh2Sb > RhSb2. Combined with the theoretical calculations, the shift of d-band center of RhxSby BIMCs depends on the Sb content. Accordingly, RhxSby BIMCs with different stoichiometric ratio display varied adsorption energy of *OH, *H and CO, giving rise to the individual HOR activity and resistance to CO poisoning. This work sheds a light on designing efficient BIMCs catalysts for energy conversion.