Electronic Structure Engineering of Pt-Ni Alloy NPs by Coupling of Gold Single Atoms on N-Doped Carbon for Highly Efficient Oxygen Reduction Reaction and Hydrogen Evolution Reaction

Abstract

Improving the catalytic activity and durability of platinum-based alloy catalysts remains a formidable challenge in the context of renewable energy electrolysis applications. Herein, a facile and rapid photochemical deposition strategy for the synthesis of gold single atoms (Au SAs) anchored on N-doped carbon is presented. These Au SAs serve as a charge redistribution support for Pt-Ni alloy nanoparticles (PtNi_NPs/Au_SA-NDC), creating an extended electron-donating interface with Pt-Ni alloy sites. Consequently, the PtNi_NPs/Au_SA-NDC hybrid catalyst manifests exceptional catalytic performance and durability in both the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) under acidic conditions. Specifically, in ORR, it exhibits a half-wave potential (0.92 V vs RHE), with a mass activity 20.4 times superior to Pt/C at 0.9 V. In HER, PtNi_NPs/Au_SA-NDC demonstrates a notably reduced overpotential of 19.1 mV vs RHE at 10 mA cm^-2 and a mass activity 38 times higher than Pt/C (at 0.25 mV). Furthermore, this hybrid catalyst displays outstanding durability, with only an 8.0 mV decay observed for ORR and a 6.9 mV decay for HER after 10 000 cycles. Theoretical calculations provide insight into the mechanism, demonstrating that isolated Au sites effectively modulate the electronic structure of Pt-Ni alloy sites, facilitating intermediate adsorption and enhancing reaction kinetics.

Keywords: PtNi alloy NPs; electrocatalyst; hydrogen evolution reaction; oxygen reduction reaction; single atoms.