A New Photoelectrocatalyst for Water Oxidation: A Polyoxometalate-Graphitic Carbon Nitride Hybrid Nanomaterial

A new photoelectrocatalyst for the water oxidation process is designed by immobilizing [CoW₁₂O₄₀]^6- (CoW₁₂) heteropolyanions on the surface of covalently modified graphitic carbon nitride nanosheets (g-C₃N₄). For this purpose, g-C₃N₄ is first modified with cysteamine hydrochloride through the well-known thiol-ene click reaction. Afterward, [CoW₁₂O₄₀]^6- heteropolyanions are immobilized on the surface of modified g-C₃N₄ nanosheets with electrostatic interaction with ammonium groups. After confirming the preparation of CoW₁₂/clicked g-C₃N₄ with various physicochemical methods, its photoelectrocatalytic activity is evaluated in the oxygen evolution reaction. The CoW₁₂/clicked g-C₃N₄ exhibits a low onset potential of 1.32 V versus NHE and a low overpotential of 230 mV at 10 mA cm^-2 with a low Tafel slope of 67 mV dec^-1 under visible light illumination. Moreover, the stability of the catalyst is investigated through the chronoamperometric measurements.