Oxygen vacancy-rich MoO <sub>3</sub> nanorods as photocatalysts for photo-assisted Li–O <sub>2</sub> batteries
Guiru Sun, Daming Yang, Zexu Zhang, Yan Wang, Wei Lü, Ming Feng
Abstract
Photo-assisted lithium–oxygen (Li–O<sub>2</sub>) batteries have been developed as a new system to reduce a large overpotential in the Li–O<sub>2</sub> batteries. However, constructing an optimized photocatalyst is still a challenge to achieve broad light absorption and a low recombined rate of photoexcited electrons and holes. Herein, oxygen vacancy-rich molybdenum trioxide (MoO<sub>3−<i>x</i></sub>) nanorods are employed as photocatalysts to accelerate kinetics of cathode reactions in the photo-assisted Li–O<sub>2</sub> batteries. Oxygen vacancies on the MoO<sub>3−<i>x</i></sub> nanorods can not only increase light-harvesting capability but also improve electrochemical activity for the cathode reactions. Under illumination, the photoexcited electrons and holes are effectively separated on the MoO<sub>3−<i>x</i></sub> nanorods. During discharging, activated O<sub>2</sub> is reduced to Li<sub>2</sub>O<sub>2</sub> by the photoexcited electrons from the MoO<sub>3−<i>x</i></sub> nanorods. The photoexcited holes can promote the decomposition of Li<sub>2</sub>O<sub>2</sub> during subsequent charging. Accordingly, the photo-assisted Li–O<sub>2</sub> batteries with the MoO<sub>3−<i>x</i></sub> nanorods deliver an ultralow overpotential of 0.22 V, considerable rate capability, and good reversibility. We think that this work could give a reference for the exploitation and application of the photocatalysts in the photo-assisted Li–O<sub>2</sub> batteries.