Enhanced photoelectrocatalytic performance of direct Z-scheme CuWO4|TiO2 heterojunction for moxifloxacin oxidation

Abstract

Films formed by the heterojunction of CuWO4 and TiO2 on conductive transparent substrate (fluorine-doped tin oxide - FTO) were utilized in moxifloxacin (MOX) degradation under polychromatic irradiation. The individual materials and the heterojunctions were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), confirming the formation of heterojunctions from pure materials. Compared to the other configuration, the electrochemical characterizations showed higher photocurrent for FTO|CuWO4|TiO2 heterojunction, associated with better charge transport in the film. Thus, the photocatalytic activity of the FTO|CuWO4|TiO2 heterojunction was investigated for MOX degradation, which achieved an oxidation of 54.4% of the drug in 150min, employing the configuration electrochemically assisted heterogeneous photocatalysis (EHP). The efficiency of the heterojunction is about 2.5 times greater than that shown by electrodes formed from their individual materials. Radical scavenger studies showed that •OH radicals are the main species responsible for MOX oxidation process. The results of XPS, radical scavenging, photoelectrochemical, and photoelectrocatalytic activity show a charge transfer mechanism associated with a direct Z-scheme and that the FTO|CuWO4|TiO2 film is promising for the degradation of organic pollutants.