Polyoxometalates covalently combined with graphitic carbon nitride for photocatalytic hydrogen peroxide production

Abstract

The polyoxometalate (POM) cluster [SiW₁₁O₃₉]⁸⁻ (SiW₁₁) with photoreductive ability has been successfully covalently combined with graphitic carbon nitride (g-C₃N₄) through an organic linker strategy. The hybrid catalyst g-C₃N₄–SiW₁₁ exhibits efficient catalytic performance (15.2 μmol h⁻¹) for photocatalytic H₂O₂ production in the presence of methanol and can stabilize the formed H₂O₂ under sunlight irradiation (AM 1.5 filter). The Koutecky–Levich plot obtained from electrochemical rotating disk electrode (RDE) analysis of the oxygen reduction reaction (ORR) for g-C₃N₄–SiW₁₁ reveals that the value of electron transfer during the ORR process is 2.76. Combining the electron spin resonance (ESR), Koutecky–Levich plots, O₂ temperature programmed desorption (O₂-TPD) and density functional theory (DFT) calculation results, the enhanced O₂ adsorption of g-C₃N₄–SiW₁₁ can promote the two-electron reduction of O₂ to H₂O₂.