A Photo-Assisted Zinc-Air Battery with MoS/Oxygen Vacancies Rich TiO Heterojunction Photocathode.

Converting solar energy into electrochemical energy is a sustainable strategy, but the design of photo-assisted zinc-air battery (ZAB) with efficient utilization of sunlight faces huge challenges. Herein, a photo-assisted ZAB of a three-electrode system using MoS/oxygen vacancies-rich TiO heterojunction as charge cathode and Fe, N-doped carbon matrix (FeNC) as discharge cathode is constructed, where MoS is chosen as solar light-responsive catalytic material and TiO acts as electron transport layer and hole blocking layer, arising from a train of thought for efficient charging under sunlight irradiation and light-independent discharging. The introduction of oxygen vacancies in TiO facilitates the temporary trapping of carriers and triggers rapid carrier transfer at the interface of the heterojunction, which hinders the recombination of photogenerated holes, thereby facilitating their further participation in the oxygen evolution reaction. Moreover, FeNC exhibits superior oxygen reduction reaction performance due to strong d-π interactions. As a result, the well-built ZABs deliver a low charge voltage (0.71 V) under illumination at 0.1 mA cm, and a high power density (167.6 mW cm) in dark. This work paves a special way for the development of ZABs by directly harvesting solar energy in charging and efficiently discharging regardless of lighting conditions.