Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

Abstract

Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO₂ was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500^°C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO₂ was further hydrogen-reduced at 300^°C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO₂ particles are near uniform. The average crystallite sizes are 17–20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO₂ and reduced Cu/TiO₂ range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p_3/2 is 933.4 eV indicating primary Cu₂O form on the TiO₂ supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO₂ support.