Unmediated photoelectrochemical charging of a Zn-air battery: The realization of the photoelectrochemical battery

Abstract A photoelectrochemical battery comprises a photoelectrode and a metal electrode, the latter being active in the construction of a metal-air battery. In the present work, Zn was used as metal electrode while a chalcogenide-semiconductor-sensitized nanoparticulate titania was employed to make the photoelectrode. Photoelectrochemical charging of the battery was achieved by reduction of Zn cations and deposition of metallic Zn on the Zn electrode playing in that case the role of cathode. A gain of about 1.5 V was obtained by photoelectrochemical charging compared to charging in the dark. Discharging of the battery may be achieved with the help of a third electrode playing the role of air electrode by switching between the photoelectrode and the air electrode. Therefore, both charging and discharging may be obtained by will and by employing the same device. Photoelectrochemical charging of the battery provides a direct means of converting and storing solar energy. In the present work, a two compartment photoelectrochemical device was employed, providing the possibility of photoelectrocatalytically oxidizing and consuming a waste, which is used as “fuel”, thus offering the double environmental benefit of renewable energy production and environmental remediation.