Visible-light-active g-C3N4/N-doped Sr2Nb2O7 heterojunctions as photocatalysts for the hydrogen evolution reaction

Abstract

Different visible-light-active g-C₃N₄/nitrogen-doped Sr₂Nb₂O₇ heterojunction photocatalysts were fabricated by deposition of graphitic carbon nitride over N-doped strontium pyro-niobate prepared by ammonolysis at different temperatures of solvothermally synthesized Sr₂Nb₂O₇ nanorods. Their photocatalytic performance was determined by the amount of hydrogen generated from water reduction under visible light irradiation. The best performing heterojunction was found to be the one formed by g-C₃N₄ and N-doped Sr₂Nb₂O₇ obtained at 700 °C. The enhanced activity of the heterojunction can be explained by better charge separation due to proper bands alignment and intimate contact between the heterojunction components as revealed by electron microscopy. A mechanism for the observed enhanced photocatalytic activity is proposed and supported by band position calculations and photoluminescence data.