Visible light-driven g-C3N4/m-Ag2Mo2O7 composite photocatalysts: synthesis, enhanced activity and photocatalytic mechanism

The g-C3N4/m-Ag2Mo2O7 composite photocatalysts with well-aligned band structures are successfully fabricated by a simple two-step method with different mass contents of m-Ag2Mo2O7. The as-prepared samples are evaluated as photocatalysts toward rhodamine B (RhB) degradation in aqueous solution under visible light irradiation (lambda > 420 nm). The results demonstrate that the photocatalytic activities of the composites are strongly influenced by the weight ratio of g-C3N4 to m-Ag2Mo2O7. When it is 6 : 1, the composite exhibits the highest photocatalytic efficiency. More specifically, this value is as high as 3.4 and 6.1 times that of pure g-C3N4 and P25 respectively. In order to investigate the mechanism causing the enhanced photocatalytic degradation, the band structures are determined by UV-vis diffuse reflection spectroscopy and the Mott-Schottky technique. Moreover, the reactive radicals involved in the photocatalytic process are examined in detail via active species trapping (AST) experiments. The improved photocatalytic activities can be attributed to the efficient separation of the photo-induced charge carriers and the strong redox capacities benefit from the synergetic effect between g-C3N4 and m-Ag2Mo2O7.