Influence mechanism insight of BiVO₄ microstructure on its photocatalytic performance

In this work, a series of monoclinic crystal bismuth vanadate (m-BiVO₄) photocatalysts with different morphology were prepared by regulating precursor solution pH value during hydrothermal reaction. The influence mechanism of m-BiVO₄ microstructure on photodegrading tetracycline hydrochloride (TC-HCl) performance were explored by the techniques of X-ray diffraction pattern (XRD), raman spectroscopy, fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS), UV-vis diffuse reflectance spectrum (UV-vis DRS), nitrogen adsorption-desorption isotherms, photocurrent (PC), photoluminescence spectra (PL) and electronic spin resonance spectra (ESR). The results reveal that the precursor solution pH value plays a great effect both on the preferential crystal growth of the m-BiVO₄ oriented along {040} facet and the formation of different morphology structures. Among all-prepared samples, the pH 4 sample (BV4) with small particle size and large specific surface area presents the best photogenerative carrier separation ability and the strongest intensity of the ·O₂⁻, which are responsible for its optimum photocatalytic performance, and the degradation rate of TC-HCl reaches more than 53% after 5 min under visible light irradiation. It is concluded that specific surface area and particle size instead of exposed crystal facet and light absorption ability of as-prepared samples, play more important role in improving the separation and utilization efficiency of electron-hole pairs and their photocatalytic activity.