One-step synthesis of CoO/g-C3N4 composites by thermal decomposition for overall water splitting without sacrificial reagents

Abstract

Using photocatalysts to split water into hydrogen and oxygen is a promising way to produce renewable energy. Efficient and stable photocatalysts are desired for overall water splitting under visible light. We demonstrate that the cobalt(II) oxide (CoO)/graphitic carbon nitride (CoO/g-C₃N₄) composites synthesized by a one-step thermal decomposition method exhibit enhanced photocatalytic efficiency for overall water splitting without sacrificial reagents. 10%CoO/g-C₃N₄ exhibits optimal photocatalytic performance, where H₂ and O₂ evolution rates are, respectively, 0.46 μmol h⁻¹ and 0.21 μmol h⁻¹ under visible light irradiation without any sacrificial reagents. It is worth mentioning that the H₂ and O₂ production almost approaches the stoichiometric ratio 2 : 1. The enhanced photocatalytic activity of CoO/g-C₃N₄ may be ascribed to the efficient charge separation and fast decomposition of H₂O₂ by CoO.