Defective TiO2 hollow nanospheres as photo-electrocatalysts for photo-assisted Li-O2 batteries

The large overpotential for conventional Li-O2 batteries is an enormous challenge, which impedes their practical application. Here, we prepare a defective TiO2 (Ov-TiO2) hollow nanosphere as photo-electrocatalyst for photo-assisted Li-O2 batteries to reduce the overpotential. Under illumination, the oxygen vacancies as a charge separation center contribute to the separation of electrons and holes. The generated electrons could promote reducing O2 to Li2O2 during oxygen reduction reaction (ORR) process, while the generated holes are beneficial to Li2O2 decomposition during oxygen evolution reaction (OER) process. Additionally, the proper concentration of oxygen vacancies will decrease the recombination rate between electrons and holes. The photo-assisted Li-O2 batteries with Ov-TiO2-650 exhibit advanced performances, such as the low overpotential (0.70 V), the fine rate capability, and the considerable reversibility accompanied with the formation/decomposition of Li2O2. We expect that these results could open a new mind to design of highly efficient photo-electrocatalysts for photo-assisted Li-O2 battery.