Optimized Adsorption of Had and OHad over Amorphous SrRuPtOxHy Nanobelts towards Efficient Alkaline Fuel Cell Catalysis

Abstract

PtRu-based catalysts toward hydrogen oxidation reaction (HOR) suffer from low efficiency, CO poisoning and over-oxidation at high potentials. In this work, an amorphization strategy is adopted for preparation of amorphous SrRuPtO_xH_y nanobelts (a-SrRuPtO_xH_y NBs). The a-SrRuPtO_xH_y NBs has optimized adsorption of intermediates (H and OH), increased number of active sites, highly weakened CO poisoning and enhanced anti-oxidation ability owing to the special amorphous structure. Consequently, a-SrRuPtO_xH_y NBs displays superior HOR performance with a mass activity of 7.5 A/mg_Pt+Ru, 25 and 5 times of that of SrRuPt(OH)_x NBs and commercial PtRu/C, respectively, and long-lasting stability. Besides, a peak power density of 750 mW/cm² and a specific power of 14.8 W/mg_Pt+Ru have been achieved for a-SrRuPtO_xH_y NBs at a low loading of 0.05 mg_Pt+Ru/cm², surpassing many reported HOR catalysts. Mechanism investigation indicates that Pt and Ru are present in oxide/hydroxide forms and H in a-SrRuPtO_xH_y NBs participates in HOR. Ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT) calculations show that there are three catalytic mechanisms participating in a-SrRuPtO_xH_y NBs, which all exhibit low catalytic barrier and highly improved HOR efficiency. This work provides a new strategy for designing high-performance catalysts towards fuel cells.