Photoinduced Oxygen Reduction Reaction Boosts the Output Voltage of a Zinc-Air Battery

Utilization of solar energy is of great interest for a sustainable society, and its conversion into electricity in a compact battery is challenging. Herein, a zinc-air battery with the polymer semiconductor polytrithiophene (pTTh) as the cathode is reported for direct conversion of photoenergy into electric energy. Upon irradiation, photoelectrons are generated in the conduction band (CB) of pTTh and then injected into the pi(2p)* orbitals of O-2 for its reduction to HO2-, which is disproportionated to OH- and drives the oxidation of Zn to ZnO at the anode. The discharge voltage was significantly increased to 1.78 V without decay during discharge-charge cycles over 64 h, which corresponds to an energy density increase of 29.0 % as compared to 1.38 V for a zinc-air battery with state-of-the-art Pt/C. The zinc-air battery with an intrinsically different reaction scheme for simultaneous conversion of chemical and photoenergy into electric energy opens a new pathway for utilization of solar energy.