Decoration of g-C3N4 by inorganic cluster of polyoxometalate through organic linker strategy for enhancing photoelectrocatalytic performance under visible light

Abstract

The efficient visible light-driven photoelectrocatalyst (denoted as g-C3N4-CO-TETA-Pr-SiW11) was designed through the organic linker strategy by combination of polyoxometalate (POM) (cluster of [SiW11O39]−8 (SiW11)) with graphitic carbon nitride (g-C3N4). For this purpose, a reactive tetradentate NH2 linker was introduced by oxidation and subsequently amidation reactions on the surface of g-C3N4 frameworks then SiW11 was bonded to the organic linker to generate g-C3N4-CO-TETA-Pr-SiW11. In this study, for the first time, this organic linker strategy was applied for covalent combination of POM and g-C3N4 to design a stable photocatalyst with high-performance. Photoelectrocatalytic performance of prepared catalysts was investigated under visible light irradiation. The photocurrent density of 0.17 mA cm−2 for g-C3N4-CO-TETA-Pr-SiW11 compared with 0.077 mA cm−2 for g-C3N4 was achieved. Investigation of the transient open circuit potential decay and photoluminescence showed the efficient electron-hole separation for g-C3N4-CO-TETA-Pr-SiW11. The arc diameter in Nyquist plots indicated the improved charge transfer and charge carrier's lifetimes after decorating of g-C3N4 with POM. Mott−Schottky plots demonstrated a greater electron transfer at the photo electrode/electrolyte interface for g-C3N4-CO-TETA-Pr-SiW112.8 in compared to g-C3N4. Also, the photoconversion efficiency exhibited more than 2.4 time enhancement for g-C3N4-CO-TETA-Pr-SiW11 photoanode compared to g-C3N4.