Engineering e g Orbital Occupancy of Pt with Au Alloying Enables Reversible Li-O 2 Batteries.

Constructing well-designed catalysts to accelerate OER catalytic activity and alleviate the charge overpotential is prevailing for achieving sophisticated Li-O 2 batteries. Herein, we report a concept for engineering the e g occupancy of Pt with M alloying (M=Au, Ru) to tune the charge overpotentials for achieving high-performance Li-O 2 batteries. The X-ray photoelectron spectroscopy results coupled with density functional theory (DFT) calculations reveal that the highly electronegative Au can capture more e g electrons from Pt, leading to less e g electrons of Pt in PtAu than that in PtRu. The lower e g occupancy of Pt atoms in PtAu alloys entails the upward shift of the Pt d band, which causes a strong binding strength towards the intermediates (LiO 2 ), thereby decreasing the OER energy barrier. As a consequence, the Li-O 2 battery with a PtAu cathode delivers a low charge overpotential of 0.36 V and superior cycle life of 220 cycles at a cutoff capacity of 1000 mAh g -1 , which is among the best in the reported noble metal-based cathodes.