Synthesis of BiVO4/bismuth oxides nano-heterostructures and evaluation of photocatalytic properties

Abstract

Semiconductors activated under visible light are of great interest for photocatalytic processes such as degradation of organic pollutants and water splitting (hydrogen production) under solar radiation. Among the materials less studied for this purpose, bismuth vanadate (BiVO4) is a semiconductor with a band gap of 2.4 eV and, therefore, can be activated under visible radiation. Some studies have reported its photocatalytic activity, while low, mainly due to the rapid recombination of the pair electron/hole. In this sense, heterostructures between semiconductors exhibit a greater separation of charge carriers and consequently an increase in the photocatalytic activity when compared to the pristine constituent phases. This project proposes the synthesis and evaluation of photocatalytic properties of heterostructures between BiVO4:Bi2O3 and BiVO4:BIOX (X = Cl, Br, I). The synthesis will be performed and optimized by Oxidant Peroxide Method (OPM) with crystallization under hydrothermal conditions. The morphological and structural characterization of heterostructures will be performed by standard techniques (XRD, Raman spectroscopy, surface area, SEM) and advanced techniques such as transmission electron microscopy, high-resolution (HRTEM). Degradation of organic pollutants (pesticides and dyes) under visible light will be used as probe to check and compare the photocatalytic potential of the heterostructures and the pristine phases. Detection measures of *OH radicals and holes formed in the valence band of the semiconductor will be performed for a better understanding about the mechanism of degradation of organic pollutants.