LAUSR

A photoelectrochemical water-splitting system featuring an organo-photocathode of a p–n bilayer was studied, where WO3 was simultaneously utilized as a photoanode. Stoichiometric formation of H2 and O2 was found to occur due to the decomposition of water. In the reference system of a WO3 photoanode and Pt counter electrode, bias voltages more than 0.4 V were needed to be applied for water splitting; however, the present system successfully led to water decomposition by applying only a low voltage of 0.1 V to the system. In the present water-splitting system, oxidizing and reducing powers can be separately generated at the WO3 photoanode and organo-photocathode, respectively, which is distinct from the reference system. Furthermore, electron transfer from WO3 (conduction band) to the hole-retained p-type layer (valence band) in the organo-photocathode can efficiently occur for completing the photoelectrochemical process, thus, resulting in a high concentration of holes available for rate-limiting O2 evolution at WO3 on the basis of efficient charge separation.