Exploratory Study of Zn_xPbO_y Photoelectrodes for Unassisted Overall Solar Water Splitting

A complete photoelectrochemical (PEC) water splitting system requires a photocathode and a photoanode to host water oxidation and reduction reactions, respectively. It is thus important to search for efficient photoelectrodes capable of full water splitting. Herein, we report on an exploratory study of a new photoelectrode family of ZnxPbOy—ZnPbO3 and Zn2PbO4—similarly synthesized by a simple and economical method and shown to be a promising photocathode (p-type semiconductor) and photoanode (n-type semiconductor), respectively. From PEC measurements, the bare ZnPbO3 photocathode achieved a photocurrent density of −0.94 mA/cm2 at 0 V versus reversible hydrogen electrode (RHE), whereas the pristine Zn2PbO4 photoanode delivered a photocurrent density of 0.51 mA/cm2 at 1.23 V versus RHE. By depositing suitable cocatalysts onto the photoelectrodes established above, we also demonstrated unassisted overall PEC water splitting, a rare case, if any, wherein a single material system is compositionally engineered for either of the photoelectrodes.