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

Abstract

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. SrNb_1−xZr_xO_2+yN_1−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.