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

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 degrees 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.