GaN:ZnO Solid Solution as a Photocatalyst for Visible-Light-Driven Overall Water Splitting

TLDR

Photocatalytic overall water splitting has been extensively studied for solar energy conversion, yet no visible‑light‑active photocatalyst has achieved satisfactory performance. We demonstrate the first visible‑light‑driven overall water splitting using a GaN:ZnO solid‑solution photocatalyst (band gap 2.58–2.76 eV) modified with RuO₂, which is stable under reaction conditions and establishes a new class of non‑oxide photocatalysts for energy conversion.

Abstract

Photocatalytic overall water splitting has been studied extensively from the viewpoint of solar energy conversion. Despite numerous attempts, none have yielded satisfactory results for the development of photocatalysts, which work under visible light irradiation to efficiently utilize solar energy. We report here the first example of visible-light-driven overall water splitting on a novel oxynitride photocatalyst, a solid solution of GaN and ZnO with a band gap of 2.58-2.76 eV, modified with RuO2 nanoparticles. In contrast to the conventional non-oxide photocatalysts, such as CdS, the solid solution is stable during the overall water splitting reaction. This is the first example of achieving overall water splitting by a photocatalyst with a band gap in the visible light region, which opens the possibility of new non-oxide-type photocatalysts for energy conversion.