Electronic Promoter Breaks the Linear Scaling Relationship: Ultra-Rapid High-Temperature Synthesis of Heterostructured CoS/SnO@C as a Bifunctional Oxygen Catalyst for Li-O Batteries.

Li-O batteries urgently needs high discharge capacity and stable cycling performance, requiring effective and reliable bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Hovenia acerba Lindl-like heterostructure composed of cobalt sulfide and tin dioxide supported on carbon substrate (CoS/SnO@C) is prepared via CO laser irradiation technology. The half-wave potential of CoS/SnO@C for the ORR is 0.88 V, while the overpotential of the OER at 10 mA cm is as low as 270 mV. The Li-O batteries employing the bifunctional CoS/SnO@C catalyst displays a high discharge specific capacity of 3332.25 mAh g and long cycling life of 226 cycles. Additionally, theory calculations demonstrate that the construction of heterostructure decreases energy barrier of the rate-determining step (RDS) for both ORR and OER. Notably, SnO behaves as the electronic promoter to optimize the electronic structure of heterostructure interface and triggers charge redistribution of CoS, which weakens the adsorption strength of the O-intermediates and allows to break the linear scaling relationship, thus further enhancing the catalytic performance of CoS/SnO@C. This research furnishes directions for the design of heterogeneous catalysts, highlighting its great potential for application in rechargeable Li-O batteries.