Direct synthesis of BaTaO2N nanoparticle film on a conductive substrate for photoelectrochemical water splitting

Abstract

Perovskite BaTaO2N has been regarded as a promising photoanode material owing to its narrow bandgap of 1.8 eV and appropriate band edge positions for photoelectrochemical (PEC) water splitting. Compared with photoanodes made with pre-synthesized BaTaO2N particles, direct deposition of BaTaO2N thin film on a conductive substrate is a promising way to improve the carrier transport capability. Herein, we propose a co-evaporation and nitridation method for the direct synthesis of BaTaO2N nanoparticle film on metal substrate for PEC water splitting. The crystallinity, morphology, and defects of the synthesized BaTaO2N nanoparticle films are varied by controlling the Ba:Ta ratios in the co-evaporated precursor films. Photoanode based on the optimized BaTaO2N nanoparticle film achieves a photocurrent density of 4.7 mA cm−2 at 1.23 VRHE and a maximum applied bias photon-to-current efficiency of 1.18% at 0.83 VRHE. Our work provides a facile method to fabricate high-crystallinity nanostructured oxynitride thin films for PEC water splitting application.