Hierarchically peony-analogous bismuth tungstate with oxygen vacancies for enhanced photocatalytic degradation of phenolic compounds

Abstract

Creating photocatalysts with improved performance to decompose noxious pollutants has attracted more attentions in recent years. To realize sewage purification, we synthesized vacancy-rich and peony-analogous bismuth tungstate with oxygen vacancies (Bi2WO6-x) photocatalysts using a soft template β-cyclodextrin by a hydrothermal method. The hierarchically three-dimensional morphology of Bi2WO6-x endows it rapid mass transformation and numerous active sites. Meanwhile, abundant oxygen vacancies simulate the generation of reactive oxidizing species, resulting in intensive photodegradation ability. By regulating reaction conditions, it is successful to selectively manufacture ample oxygen vacancies and dispersive three-dimensional structure of Bi2WO6-x. With optimal template ratio, reaction temperature and reaction time, Bi2WO6-x exhibits strong degeadation performance of phenolic compounds. Based on the research findings, electrons, holes, superoxide radicals and singlet oxygen are main reactive species. Besides, the practicability of Bi2WO6-x is discussed through changing water matrix during photodegrade phenol. Degradation products are identified by gas chromatography-mass spectrometry technique and their toxicities are estimated by quantitative structure-activity relationship prediction, indicating various degrees of toxicity attenuation. Finally, the effective degradation process is the result of synergistic interaction among microstructure, reactive oxygen species and abundant oxygen vacancies. The dominant reactive oxygen species are •O2− and 1O2 generated by Bi2WO6-x. Moreover, oxygen vacancies played an important role in separating electrons and holes. This work further presents that introducing oxygen vacancies and regulating morphology synchronously are feasible to enormously boost the photodegradation activity for decomposing organic pollutants.