Degradação fotoeletrocatalítica de moxifloxacina sobre heterojunção de esquema z direto de CuWO4|TiO2.

Abstract

CuWO4 and TiO2 semiconductors were synthesized, respectively, by electrodeposition and solgel methods, and supported on a transparent conductive substrate (fluorine-doped tin oxide – FTO) aiming at the formation of heterojunctions to be used in the degradation of moxifloxacin (MOX) under polychromatic irradiation. The individual materials and heterojunctions were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-rays spectroscopy (EDX), confirming the formation of the heterojunctions from pure materials. The photocurrent density, obtained from the linear sweep voltammetry (LSV) technique, indicated values of 2.19, 18.28, 17.54 and 8.28 μA cm-2 (0.7 V vs. Ag/AgCl) for the FTO|TiO2, FTO|CuWO4, FTO|CuWO4|TiO2 and FTO|TiO2|CuWO4 films, respectively. Thus, electrochemical characterizations indicated higher photocurrent and better charge transport for the FTO|CuWO4|TiO2 heterojunction when compared to the inverse heterojunction. With this, the photocatalytic activity of the FTO|CuWO4|TiO2 heterojunction was investigated for MOX degradation, in which a degradation rate of 54.4% employing the configuration of electrochemically assisted heterogeneous photocatalysis (EHP) was achieved. This heterojunction indicated an efficiency approximately 2.5 times greater than that obtained by electrodes formed from pure films. Studies of radical scavengers have shown that hydroxyl radicals (•OH) are the main species responsible for the MOX oxidation process. Finally, the results obtained from XPS analysis, radical scavenging, photoelectrocatalytic and photoelectrochemical activities indicated a charge transfer mechanism associated with a direct Z-scheme, promoting efficient separation of photogenerated charges and considerable photocatalytic activity. Furthermore, the FTO|CuWO4|TiO2 film shows promise for the degradation of organic pollutants