Modulating in-plane electron density of molybdenum diselenide via spontaneously atomic-scale palladium doping enables high performance lithium oxygen batteries

Lithium-oxygen batteries (LOBs) are considered to be one of the most competitive energy storage devices due to their high theoretical energy density . However, challenges including poor catalytic activity and durability of the oxygen electrode seriously hinder the in-depth development of LOBs. Adjusting the surface electronic structure of the oxygen electrode provides a new prospect for realizing highly efficient electrocatalysts . In this contribution, we report that atomic-scale palladium (Pd) involving in MoSe 2 (Pd–MoSe 2 ) is capable of adjusting the in-plane electron density of MoSe 2 via spontaneous interface chemical reactions, thereby accelerating the electron migration along the in-plane direction. The synergy between the created Se vacancies and Pd atoms can further increase the electroactive sites on the Pd–MoSe 2 surface, which is conducive to improving the catalytic activity of the electrode and thereby accelerating the kinetics of oxygen electrode reactions. The results show that Pd–MoSe 2 based LOBs exhibit excellent electrochemical performance such as high Coulombic efficiency (97.81%) as well as extended cycle life (1952 h). This work shows that the adjustment of in-plane electron density by exotic metal atom is a viable strategy to improve the catalytic activity of layered transition metal selenide, which provides the possibility of developing highly efficient electrocatalysts for LOBs.