Oxygen vacancy-rich MoO 3 nanorods as photocatalysts for photo-assisted Li–O 2 batteries

Abstract

Photo-assisted lithium–oxygen (Li–O₂) batteries have been developed as a new system to reduce a large overpotential in the Li–O₂ 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_3−<i>x</i>) nanorods are employed as photocatalysts to accelerate kinetics of cathode reactions in the photo-assisted Li–O₂ batteries. Oxygen vacancies on the MoO_3−<i>x</i> 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_3−<i>x</i> nanorods. During discharging, activated O₂ is reduced to Li₂O₂ by the photoexcited electrons from the MoO_3−<i>x</i> nanorods. The photoexcited holes can promote the decomposition of Li₂O₂ during subsequent charging. Accordingly, the photo-assisted Li–O₂ batteries with the MoO_3−<i>x</i> 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–O₂ batteries.