Photocatalytic degradation of phenol by core–shell Cu@TiO2 nanostructures under visible radiation

Abstract

Even allowing high degradation efficiency, TiO2 does not support many large-scale applications, mainly due to the high operational cost related to the use of artificial radiation sources. On the other hand, it is well known that the TiO2 response to solar radiation can be increased by association with noble metals, due to the phenomenon of surface plasmonic resonance. Thus, the present study aimed to prepare copper nanoparticles and their incorporation into commercial titania (Evonik Aeroxide P-25) by the wet impregnation method. Characterization studies confirmed the formation of a core–shell nanostructure (Cu@TiO2) formed by irregular shape particles with a mean size between 20 and 30 nm. The incorporation of Cu significantly reduced the optical bandgap energy (Eg) of the materials, ranging from 3.17 eV for TiO2 P-25 to 2.67 eV for Cu@TiO2 materials containing 3.0% of copper. Characterization studies carried out by cathodoluminescence shown that high concentrations of copper reduced the lifetime of photogenerated electrons and holes, which suggests its role as a charge recombination center. Thus, the presence of copper decreased the efficiency of TiO2 on the UV–Vis mediated photocatalytic degradation of phenol, while in the presence of visible radiation only Cu@TiO2 materials containing 0.5% of copper showed high degradation efficiency.