Enhancing CO tolerance in hydrogen oxidation reaction through synergy of surface-modified MoOx with PtRu alloy

Abstract

Even trace amounts of CO impurities present in low-cost crude hydrogen can severely poison Pt-based catalysts. For proton exchange membrane fuel cells (PEMFCs), the development of hydrogen oxidation reaction (HOR) catalysts capable of enduring CO contamination is of significant economic importance. In this study, we propose a new strategy to synergistically enhance the CO tolerance of PtRu alloys by incorporating MoO_x. The MoO_x modified on PtRu/C catalysts can initiate the oxidation of CO adsorbed on its surface at potentials as low as 0.125 V. The synergy effect of MoO_x and bifunctional PtRu ensures sufficient HOR stability even under hydrogen containing high CO concentrations. The resulting PtRu-MoO_x/C catalyst exhibits a 4.6-fold increase in the remained HOR current compared with commercial PtRu/C, after two hours in a hydrogen environment containing 10,000 ppm CO. Under typical testing condition of H₂/1,000 ppm CO, PtRu-MoO_x/C maintains over 80% of the initial current density even after ten hours, significantly outperforming PtRu/C (30%) and most previously reported catalysts.