Solid Solution of GaN and ZnO as a Stable Photocatalyst for Overall Water Splitting under Visible Light

Abstract

Large-scale hydrogen production from water using only solar energy is an ultimate goal for the supply of clean, recyclable energy, and several reactions and schemes have been proposed. Overall water splitting using a particulate photocatalyst is one attractive solution with a wide range of applications. A number of photocatalysts have been proposed, and some have achieved high quantum efficiencies. Unfortunately, most of these photocatalysts consist of metal oxides and work only in the ultraviolet (UV) region. To effectively utilize solar energy, it is necessary to develop a material that will function under visible light. This paper reviews the recent development of such a photocatalyst, specifically focusing on efforts by the authors’ group to prepare a solid solution of GaN and ZnO. This new material is capable of splitting water into hydrogen and oxygen under visible light (λ > 400 nm) with good reproducibility.