Nanostructured TiO2 photocatalyst modified with Cu for improved imidacloprid degradation

We investigated the role of Cu(II) ions, their local atomic structure and chemical state in the Cu-modified immobilized nanostructured TiO2 photocatalysts used for imidacloprid degradation under UV/VIS-radiation. Catalyst samples were prepared via electrochemical anodization and modified with different Cu concentrations (0.2-1 M). The catalysts' structure and morphology were characterized by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy, UV-VIS-NIR spectroscopy, Photoluminescence spectroscopy and X-ray absorption spectroscopy: extended X-ray absorption fine structure and X-ray absorption near edge structure. The EXAFS results indicate formation of Ti-O-Cu connections, suggesting that the Cu(II) cations are attached to TiO2 surface which contributes to the photocatalytic activity improvement, i.e. Cu(II) ions are free electron traps that reduce high recombination rate of photo generated charge carriers. The results here demonstrate the role of Cu(II) cations on photocatalytic activity of the Cu@TiO2 photocatalyst.