A visible-light-induced photoelectrochemical water-splitting system featuring an organo-photocathode along with a tungsten oxide photoanode

Abstract

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.