Mg modified BaTaO2N as an efficient visible-light-active photocatalyst for water oxidation

• Published in: Journal of catalysis 2020-03, Vol.383, p.135-143
• Main Authors: Zhang, Hong, Wei, Shunhang, Xu, Xiaoxiang
• Format: Article
• Language: English
• Subjects: BaTaO2N; Mg modification; Photocatalyst; Water oxidation; Water splitting
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2020.01.005

Mg modifications over BaTaO2N reduce Ta4+ defects concentration, contributing to much improved photocatalytic activities for water oxidation reactions. [Display omitted] •Mg modifications strengthen Ta-O/N bonds in BaTaO2N.•Ta4+ defects concentration decreases in Mg modified BaTaO2N.•Photocatalytic performance is much improved after Mg modifications.•Band edges are positively shifted in Mg modified BaTaO2N.•Mg contributes to improved interactions between BaTaO2N and CoOx. BaTaO2N owns a promising band gap of 1.8 eV and suitable band edge positions but generally exhibits poor photocatalytic activity for water splitting reactions. In this work, we have modified BaTaO2N by introducing Mg to the B site of perovskite lattice to form a new compound, i.e. BaTa0.95Mg0.05O2+xN1−y. This modification results in an alteration to a number of important parameters such as unit cell size, nitrogen content, optical absorption and microstructures etc. More importantly, Mg modifications are responsible for stronger Ta-O/N bonds, lower Ta4+ defects concentration and positively shift of band edge positions, which in turn contribute to high photocatalytic activities for water oxidation reactions. Apparent quantum efficiency as high as 2.59% has been realized at 420 ± 20 nm, being the highest for BaTaO2N reported to date under similar conditions. Further photoelectrochemical analysis confirms better charge utilizations in Mg modified BaTaO2N.