Z-scheme Ag-loaded g-C3N4/CuNb2O6 composite photocatalyst for RhB dye degradation.

Photocatalysis is considered to be one of the possible routes to solve energy crises at a low cost. Graphitic-C₃N₄ combined with other semiconductors at the nanoscale has demonstrated a promising potential in photocatalysis application owing to the heterojunction configuration. In this study, Ag/g-C₃N₄/CuNb₂O₆-4 (mass ratio of CuNb₂O₆ to g-C₃N₄ = 1:4) composites were prepared by photo-deposition of Ag particles on the hydrothermally synthesized g-C₃N₄/CuNb₂O₆-4 composites. The microstructure, morphology, and light absorption property of the photocatalysts were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectroscopy. The photocatalytic properties of photocatalysts and active species responsible for the degradation of RhB dye under visible light were investigated. After loading Ag particles on the g-C₃N₄/CuNb₂O₆-4 composites, the resulting Ag/g-C₃N₄/CuNb₂O₆-4 composites show a bandgap of ~ 2.31 eV and a significant increase in photocatalytic efficiency. In particular, the photocatalytic activity of 11% Ag/g-C₃N₄/CuNb₂O₆-4 composite (Ag mass fraction = 11%) is nearly seven times that of orthorhombic CuNb₂O₆ and 3.8 times that of g-C₃N₄/CNO-4 composite. The Z-scheme heterojunction has been successfully formed in the Ag/g-C₃N₄/CuNb₂O₆-4 composites and it enhances the photocatalytic performance significantly with the best degradation efficiency of 88% after 2 h. [ABSTRACT FROM AUTHOR]