Tuning Dual Catalytic Active Sites of Pt Single Atoms Paired with High-Entropy Alloy Nanoparticles for Advanced Li-O₂ Batteries.

Abstract

To achieve a long cycle life and high-capacity performance for Li-O₂ batteries, it is critical to rationally modulate the formation and decomposition pathway of the discharge product Li₂O₂. Herein, we designed a highly efficient catalyst containing dual catalytic active sites of Pt single atoms (Pt_SAs) paired with high-entropy alloy (HEA) nanoparticles for oxygen reduction reaction (ORR) in Li-O₂ batteries. HEA is designed with a moderate d-band center to enhance the surface adsorbed LiO₂ intermediate (LiO₂(ads)), while Pt_SAs active sites exhibit weak adsorption energy and promote the soluble LiO₂ pathway (LiO₂(sol)). An optimal ratio between LiO₂(ads) and LiO₂(sol) pathway was realized to modulate Pt_SAs and HEA active sites via regulating the etching conditions in the dealloying synthesis process for obtaining high-performance Li-O₂ batteries. The ORR kinetics are accelerated, and the parasitic reactions are restrained in the Li-O₂ batteries. As a result, Li-O₂ batteries based on the HEA@Pt-Pt_SAs catalyst demonstrate an ultralow overpotential (0.3 V) and ultralong cycling performance of 470 cycles at 1000 mA g^-1. The insights into the synthetic strategies and the importance of balancing the ORR pathways will offer guidance for devising multisite synergistic catalysts to accelerate redox-reaction kinetics for Li-O₂ batteries.