Activation of persulfate ions by QDs-sized Z-scheme TiO2-x/Cu3Mo2O9 photocatalysts in visible-light detoxification of organic contaminants

Abstract

As known, colored TiO2-x is a promising material in the photocatalytic detoxification of water pollutants. Herein, brown TiO2-x was combined with Cu3Mo2O9 nanoparticles to fabricate quantum dot-sized photocatalysts through hydrothermal method preceded calcination at 350 C-degrees. The optical, electrochemical, textural, structural, and morphological features of the prepared photocatalysts were explored via various techniques. The photocatalytic ability of the materials was studied in the presence of persulfate ions (PS) upon visible light to remove different pollutants. After adding PS, the TiO2-x/Cu3Mo2O9 (1%)/PS system represented an efficient performance for the degradation of tetracycline (TC), cephalexin (CFX), fuchsine (FS), and methyl orange (MO). The rate constants of TC oxidation in the TiO2-x/Cu3Mo2O9 (1%)/PS system were respectively 333, 245, 198, 190, 95.2, 92.9, 77.9, and 2.03 times higher than the TiO2, PS, TiO2/PS, Cu3Mo2O9, Cu3Mo2O9/PS, TiO2-x, TiO2-x/PS, and TiO2-x/Cu3Mo2O9 (1%) systems. So, the synergistic effect of PS and heterogeneous photocatalysis was confirmed by the TiO2-x/Cu3Mo2O9 (1%) material in the removal reactions. The quenching tests demonstrated that the O-center dot(2)-, h(+), (OH)-O-center dot, and (SO4-)-S-center dot are key reactive species. Finally, a Z-scheme mechanism was suggested for the degradation reactions by TiO2-x/Cu3Mo2O9 /PS system.