Quasi-Atomic Nickel Hydroxides Loaded on Graphitic Carbon Nitride for Enhanced Light-Driven Catalysis

Abstract

The incorporation of quasi-atomic Ni(OH)₂ clusters onto graphitic C₃N₄ (gCN) remarkably enhances the photocatalytic production of hydrogen peroxide (H₂O₂) and benzaldehyde (BAL) from benzyl alcohol (BA) in water under visible light at 440 nm. Upon loading Ni(OH)₂, H₂O₂ production reaches 306 µmol g⁻¹ h⁻¹ and BAL production reaches 270 µmol L⁻¹ h⁻¹. The high photocatalytic performance is attributed to the formation of ultrasmall clusters of Ni(OH)₂, which reduce recombination by trapping holes, thereby increasing the activity (BA conversion). Efficient hole transfer to BA is also facilitated, enhancing selectivity (BAL selectivity). Upon the addition of Ni(OH)₂, the steady-state electron population photoexcited by visible light increases 5.5-fold. The proposed modification of gCN with Ni achieves nearly 100% efficiency in both activity and selectivity to produce H₂O₂, while also generating BAL, a value-added product. This demonstrates its potential for sustainable chemical transformations using visible light and water as a green solvent.