Synthesis, Characterization and Testing of Bi2MoO6-Based Semiconductors Applied in Photocatalytic Water Treatment

Abstract

Photocatalysis has received increasing attention in recent years as an effective technology in wastewater treatment applications. In this project, bismuth molybdate (Bi2MoO6), which is a popular visible-light-driven photocatalyst, was prepared by solvothermal and hydrothermal methods. The synthesis conditions, including thermal reaction temperature, synthesis duration, and precursor stirring time of the solvothermal method were optimized based on the photodegradation of Rhodamine B (RhB) under visible light irradiation. Furthermore, the CeO2/Bi2MoO6 composites with different CeO2 loading content were successfully prepared by the wet impregnation route and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and diffuse-reflection spectroscopy (DRS). The photodecomposition of RhB aqueous solution under visible light irradiation indicated that composites showed enhancements in degradation activity and 20 wt% CeO2/Bi2MoO6 exhibited the highest photocatalytic activity which was 24.13% and 83.33% higher than those of Bi2MoO6 and CeO2, respectively. This enhancement could be attributed to the formation of heterojunctions that effectively suppressed the recombination of holes and electrons. Quenching experiments revealed that photo-induced holes and superoxide radicals (O2•-) were the main active species during the degradation process. Reusability was assessed by a set of 5 cycling degradation experiments and the results indicated that the composite could be applied long-term. Moreover, the effect of some operating parameters including temperature, initial pH, catalyst dosage and initial substrate concentration were investigated.