Zr modified SrNbO2N as an active photocatalyst for water oxidation under visible light illumination

With an absorption edge as far as 690 nm, SrNbO2N holds great promise for solar energy conversion. However, very poor photocatalytic activity is generally seen for SrNbO2N, limiting its practical applications as a photocatalyst. In this work, SrNbO2N is modified by introducing Zr at B sites, i.e. SrNb1−xZrxO2+yN1−y (0 ≤ x ≤ 1), which are then investigated as photocatalysts for water oxidation reactions. Zr modification not only induces porous microstructures and inhibits the formation of Nb4+ defects, but it also ameliorates the surface hydrophilicity of SrNbO2N. Clear improvements in photocatalytic water oxidation have been realized after Zr modification and an apparent quantum efficiency of as high as 1.44% has been achieved. Further analysis of the band edge alignments suggests that Zr modification positively shifts the valence band edge of SrNbO2N, which favors water oxidation reactions.