Low-temperature synthesis of BaTaO₂N by an ammonothermal method

Abstract

A Ta-based oxynitride photocatalyst, BaTaO₂N, was obtained by an ammonothermal method using supercritical ammonia as a reaction medium. Oxynitrides are generally obtained via multi-step reaction processes requiring high-temperature nitridation of an oxide precursor. In this study, we have successfully synthesized an oxynitride via a simple one-pot method. Moreover, BaTaO₂N was obtained at a temperature approximately 300°C lower than that of the conventional method. NaNH₂ was selected as a basic mineralizer with the aim to improve the solubility of the starting materials in supercritical ammonia. Addition of NaNH₂ led to a BaTaO₂N material with improved crystallinity (i.e., NaNH₂ inhibited lattice defects). Under visible light irradiation, Pt-loaded BaTaO₂N samples reduced water into hydrogen in the presence of a sacrificial reagent.