One-step synthesis of CoO/g-C ₃N ₄ composites by thermal decomposition for overall water splitting without sacrificial reagents

Abstract

10%CoO/g-C ₃N ₄ exhibits good photocatalytic performance under visible light irradiation without any 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-C ₃N ₄) composites synthesized by a one-step thermal decomposition method exhibit enhanced photocatalytic efficiency for overall water splitting without sacrificial reagents. 10%CoO/g-C ₃N ₄ exhibits optimal photocatalytic performance, where H ₂ and O ₂ 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 H ₂ and O ₂ production almost approaches the stoichiometric ratio 2 : 1. The enhanced photocatalytic activity of CoO/g-C ₃N ₄ may be ascribed to the efficient charge separation and fast decomposition of H ₂O ₂ by CoO.