Investigation doping effects of Copper to enhance photocatalytic performance of Tungsten Trioxide for advanced Tetracycline elimination even under visible light

Abstract The goal of the research was to improve photocatalytic activity of WO₃ by Cu doping to use for tetracycline decomposition. Firstly, the Cu dopant worked as nuclei for the crystallization of WO₃ leading to an increase in growth and sizes of formed crystals. However, the incorporation of Cu dopants in the WO₃ induced significant deviation into the WO₃ lattice inhibiting agglomeration of the WO₃ crystals to form large particles. Therefore, the crystal sizes of Cu-WO₃ were bigger than the WO₃ crystals, however, the Cu-WO₃ particles compared to WO₃ particles were smaller. By existing in the WO₃ lattice, the Cu dopant created an intermediate band to decrease band-gap energy and to boost electron-hole separation of the WO₃. Therefore, the synthesized Cu-WO₃ effectively generated large electrons and holes for the decomposition of tetracycline under visible light excitation. The study investigated that 3Cu-WO₃, in which the Cu doping ratio was 3% mole, showed the highest tetracycline decomposition efficiency (∼79.5%). This was due to the doping of Cu into the WO₃ lattice reached a limit, excess that limitation, Cu precursor formed CuO distributing on the WO₃ surface to eclipse light reaching the material leading to decrease in electron-hole separation rate due to limited light absorption or decrease in photocatalytic degradation. Finally, the Cu-WO₃ exhibited novel stability during the degradation of tetracycline.