Cation‐Doped SrTaO<sub>2</sub>N Prepared through a Flux Method for Visible‐Light‐Driven Water Splitting
Keisuke Obata, Tomohiro Higashi, YE Fei-fan, Masao Katayama, Kazuhiro Takanabe
Abstract
Abstract Semiconductor photocatalysts for water splitting is considered one of the most promising technologies for solar energy conversion. SrTaO 2 N has a band gap of 2.1 eV and is a candidate for achieving visible‐light‐driven water splitting. However, its poor charge separation efficiency limits its water splitting efficiency, which can be attributed to the charge recombination induced by reduced Ta 4+ sites, which act as recombination centers. This study focuses on the improvement of photocatalytic activity of SrTaO 2 N by introducing foreign metal cations with a low oxidation state to suppress the formation of reduced Ta 4+ sites. Among the investigated samples, 1.0 mol % Ga 3+ ‐doped SrTaO 2 N was found to improve the photocatalytic activity significantly. X‐ray photoelectron spectroscopy (XPS) data show that the formation of Ta 4+ species is suppressed after Ga doping, which might be responsible for the photocatalytic activity improvement of SrTaO 2 N.