Surface modification of Cu2O-CuO photocatalyst on Cu wire through decorating with TiO2 nanoparticles for enhanced visible light photocatalytic activity

Abstract

In this paper, the fabrication of Cu2O-CuO/TiO2 nanocomposite photocatalysts on Cu wire was performed successfully via chemical-thermal oxidation and sol-gel process. The chemical-thermal oxidations were applied for Cu2O-CuO nanostructure fabrication on the Cu wire surface. The sol-gel process was utilized for TiO2 nanoparticles decoration as a surface modification process for photocatalytic activity improvement. The X-ray diffraction analysis (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) showed the coexistence of multiple components including Cu2O, CuO, Cu, and TiO2 in the nanocomposite. Field emission electron scanning microscopy (FESEM) results demonstrated remarkable changes in morphology by applying different preparation conditions. The calculated band gap energies from UV–vis diffuse reflectance spectra (DRS) were in the range of 1.72–1.96 eV demonstrating their activity under visible light illumination. Photoluminescence (PL) data indicated delayed recombination of electrons - holes with surface modification due to the formation of heterostructure in the nanocomposite. The investigation of the photocatalytic performance was performed by methylene blue (MB) and methylene orange (MO) dye degradation under visible light illumination and 87 % degradation efficiency was obtained after 120 min. The active species trapping tests involving scavengers demonstrated that the superoxide radicals and holes play more noticeable roles compared to hydroxyl radicals in photocatalytic degradation. The ability to easily separate photocatalyst wires from aqueous solution along with good stability after several cycles of use in degradation is a unique feature of the prepared photocatalysts.