Electrochemical Properties of BaTaO₂N Photocatalyst with Visible‐Light‐Driven Water Splitting Capability

Abstract

Abstract A BaTaO 2 N (BTON) particulate photocatalyst enables solar water splitting in response to visible light irradiation at wavelengths of up to 640 nm. The specific nitridation conditions produced distinct types of BTON particles with the capability of one‐step overall water splitting (Active‐BTON) and without the overall water splitting activity (Inactive‐BTON). Unveiling the intrinsic differences between the active‐ and inactive‐BTON particles is crucial for obtaining more in‐depth information about the water splitting activity. Herein, we investigated the electrochemical (EC) and photoelectrochemical (PEC) properties of these BTON photocatalysts using the particulate‐based photoelectrodes for water splitting. EC measurements, including Mott–Schottky analysis, revealed that the flat band potential of Active‐BTON is located at a potential that is more positive than that of Inactive‐BTON, whereas the carrier concentration of Active‐BTON is one‐tenth lower than that of Inactive‐BTON. Irrespective of the pH value of the 1.0 M potassium phosphate aqueous solution, the Active‐BTON‐based photoelectrodes showed a higher photocurrent than that of Inactive‐BTON under simulated AM 1.5G solar illumination. The PEC performance of the BTON was found to be limited by the electrocatalytic activity of the CoO x co‐catalyst, specifically the electrolyte pH.