Nanostructure Engineering and Electronic Modulation of a PtNi Alloy Catalyst for Enhanced Oxygen Reduction Electrocatalysis in Zinc-Air Batteries.

PtNi nanoalloys have demonstrated electrocatalysis superior to that of benchmark Pt/C catalysts for the oxygen reduction reaction (ORR), yet the underlying mechanisms remain underexplored. Herein, a PtNi/NC catalyst comprising PtNi nanoparticles (∼5.2 nm in size) dispersed on N-doped carbon frameworks was prepared using a simple pyrolysis strategy. Benefiting from the individual components and a hierarchical structure, the PtNi/NC catalyst exhibited outstanding ORR activity and stability ( E 1/2 = 0.82 V vs RHE and 8 mV negative shift after 20000 cycles), outperforming a commercial 20 wt % Pt/C catalyst ( E 1/2 = 0.81 V and 32 mV negative shift). A prototype zinc-air battery constructed using PtNi/NC as the air electrode catalyst achieved highly enhanced electrochemical performance, outperforming a battery constructed using Pt/C as the ORR catalyst. Density functional theory calculations revealed that the improved ORR activity of the PtNi nanoalloys originated from charge redistribution with a suitable metal d-band center to promote the formation of the ORR intermediates.