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.

Keywords: Cu dopant, WO3, Photocatalysis, Tetracycline removal, Recycling