Photo-excited Oxygen Reduction and Oxygen Evolution Reactions Enable a High-Performance Zn-Air Battery

The storage of solar energy in battery systems is pivotal for a sustainable society, which faces many challenges. Herein, a Zn-air battery is constructed with two cathodes of poly(1,4-di(2-thienyl))benzene (PDTB) and TiO₂ grown on carbon papers to sandwich a Zn anode. The PDTB cathode is illuminated in a discharging process, in which photoelectrons are excited into the conduction band of PDTB to promote oxygen reduction reaction (ORR) and raise the output voltage. In a reverse process, holes in the valence band of the illuminated TiO₂ cathode are driven for the oxygen evolution reaction (OER) by an applied voltage. A record-high discharge voltage of 1.90 V and an unprecedented low charge voltage of 0.59 V are achieved in the photo-involved Zn-air battery, regardless of the equilibrium voltage. This work offers an innovative pathway for photo-energy utilization in rechargeable batteries.