Novel Preparation of Bi/BiVO4 Catalyst Supported by Alkali-Modified Diatomite and its Visible Light-Driven Degradation Performance

Abstract

The manufacture of diatomite-supported composite catalyst with enhanced photocatalytic activity is of great interest for wastewater treatment. In this study, the pretreated diatomite (PD) with 5[Formula: see text]wt.% NaOH solution possessed better pore structure and large specific surface area. A facile hydrothermal-photoreduction method was adopted to prepare Bi/BiVO4/PD composite. The chemical composition, microstructure morphology and pore structure of samples were investigated by means of XRF, XRD, SEM, TEM, EDS, XPS and BET methods. The results showed that the metallic Bi was uniformly deposited on the BiVO4. After loaded on PD, both surface area and total pore volume had a significant increase. In addition, UV-vis diffuse reflectance spectra presented that the absorption capacity of Bi/BiVO4/PD-25% composite in the visible light range was remarkably high due to the surface plasmon resonance (SPR) caused by metallic Bi. From photoluminescence (PL) spectra and transient photocurrents, the heterojunction formed between Bi/BiVO4 and PD helped promoting the separation and migration of photo-generated carriers, which in turn led to higher photocatalytic activity. Compared with Bi/BiVO4, Bi/BiVO4/PD loaded with 25[Formula: see text]wt.% PD showed highest decolorization rate for rhodamine B (RhB), malachite green (MG), methylene blue (MB), methyl orange (MO) and lemon yellow (LY) under visible light irradiation. According to trapping experiments on free radicals, the active species that played a decisive role in RhB degradation were h[Formula: see text] and [Formula: see text]. Findings from this study suggest that Bi/BiVO4/PD-25% composite holds great promise for dye degradation and wastewater treatment.