Preparation and photocatalytic performance of montmorillonite-BiVO₄/BiOIO₃ composite

Montmorillonite supported BiVO₄/BiOIO₃ composites (MMT-BiVO₄/BiOIO₃) were prepared by hydrothermal method using hexadecyl trimethyl ammonium bromide modified montmorillonite, BiVO₄ and precursor of BiOIO₃ as raw material. Compared to BiOIO₃, the absorption edge of composite materials occur red shift to visible light region and absorption intensity is enhanced from 200 nm to 800 nm in UV-vis DRS. The fluorescence intensity of 40%MMT-65%BiVO₄/BiOIO₃ located near 579 nm is lower than that of BiVO₄ or BiOIO₃. Its half circular diameter is the smallest in electrochemical impedance spectra. These results indicate that the recombination rate of photogenerated carriers is reduced by constructing II-scheme BiVO₄/BiOIO₃ heterojunction. Meanwhile, the electrostatic attraction between modified montmorillonite and photoelectron further improve the separation rate of photogenerated charge carriers and is beneficial for photocatalytic reactions. In the experiment of simulating visible light degradation of acid fuchsin (AF), the degradation rate of AF is 97.7% with 60 min by 40%MMT-65%BiVO₄/BiOIO₃ as photocatalysts. The pseudo-first-order rate constant is 0.0532 min⁻¹ and the active species are h⁺, \text•\textO_2^- in photodegradation reaction. As well as, the composite has excellent adsorption performance for cationic dyes, such as crystal violet (CV), methylene blue (MB) and malachite green (MG). The photodegradation effect on methyl orange (MO), rhodamine B (RhB) and tetracycline hydrochloride (TC) is more effective.