Two step water splitting into H2 and O2 under visible light by ATaO2N (A=Ca, Sr, Ba) and WO3 with IO3-/I- shuttle redox mediator

摘要

Two-step water splitting into H2 and O2 under visible light irradiation is examined combining Pt-ATaO2N (A=Ca, Sr, Ba) as a H2 evolution photocatalyst and Pt-WO3 as an O2 evolution photocatalyst by IO3-/I- shuttle redox-mediator. Overall water splitting proceeds when Pt-CaTaO2N or Pt-BaTaO2N is used for H2 evolution photocatalyst, whereas photo-induced self-oxidative decomposition is predominant for Pt-SrTaO2N. The onset wavelengths of H2 evolution almost accord with the absorption edges of CaTaO2N and BaTaO2N. The available wavelength of light for H2 evolution in the present two-step water splitting system has been extended to 660 nm by using BaTaO2N.