Synthesis and characterization of Cu–BiVO₄/MCM-41 composite catalysts with enhanced visible light photocatalytic activities

Cu–BiVO₄/MCM-41 photocatalysts with tunable Cu content were synthesized via a simple sol–gel method using citric acid as chelating agent. The structure, morphology and optical properties of the composites were characterized by means of X-ray diffraction, field emission scanning electron microscope and ultraviolet–visible spectroscopy. The photocatalytic activity was investigated by the photocatalytic degradation of methylene blue (MB) under visible light. The experimental results showed that all as-prepared catalysts belonged to the monoclinic scheelite phase, and slight portion of Cu²⁺ incorporation might lead to lattice expansion of BiVO₄. Furthermore, loading BiVO₄ with MCM-41 molecular sieve could suppress the aggregation of pure catalyst particles effectively. Among all as-prepared samples, 5 %Cu–BiVO₄/MCM-41 exhibited the best photocatalytic activity with a 97 % of MB removal in 3 h, moreover, its pseudo-first-order reaction rate constant was 3 times higher than that of pure BiVO₄. The enhanced photocatalytic ability might be ascribed to the excellent absorption performance, low recombination of photogenerated charge carriers and enhancement of light adsorption.