Defect engineering modulated MoSe2 cathode achieves highly effective photo-responsive zinc ion battery

Photo-responsive batteries coupled with solar energy collection, conversion, and storage are promising power sources for the next generation. Dual-function photocathode with high photo-responsive characteristics and energy storage capacity to simultaneously collect and store solar energy is an ideal technological tool. However, low photoelectric conversion efficiency, carrier recombination, and poor electrical conductivity have restricted the development of dual-functional photocathodes. Herein, molybdenum selenide with selenium vacancies (named as MoSe2-VSe) is designed as a photocathode for photo-responsive zinc ion batteries. The specific capacity increased from 186.2 mAh g-1 to 234.7 mAh g-1 under visible light (1 Sun) of 0.1 A g-1. At the current density of 0.1 A g-1, the photoelectric conversion efficiency reaches 0.58 %. Notably, the photo-responsive Zn-ion battery exhibits a photo self-charging voltage of 0.98 V after 6 h illumination. The results show that the photocathode with Se vacancies can promote electron transboundary movement, reduce carrier recombination, and decrease the diffusion barrier of zinc ions. This work presents an encouraging and effective strategy for designing dualfunction photocathodes and lays the foundation for the development of photo-responsive batteries.