Enhanced Oxygen Reduction Reaction Performance by Adsorbed Water on Edge Sites.

Pt-based alloy nanoparticles have broad application prospects as cathode catalyst materials for proton-exchange membrane fuel cells (PEMFCs). Optimization of the oxygen adsorption energy is crucial to boost the performance of oxygen reduction catalysis. We successfully synthesized well-dispersed PtNi tetrahedra and obtained the PtNi/C catalyst adopting the one-pot synthetic protocol, which exhibits superb activity and good long-term stability for oxygen reduction reaction (ORR), achieving a mass activity of 1.53 A/mg at 0.90 V, which is 12 times higher than that of commercial Pt/C. On combining X-ray photoelectron spectroscopy and density functional theory calculations, abundant water is adsorbed stably on the PtNi alloy surface. We find that the intense interaction between the adsorbed O atom and adsorbed water can weaken the adsorption of oxygen, contributing to the ORR performance.