Photoreduction of Copper Ions Using Silica-Surfactant Hybrid and Titanium (IV) Oxide under Sulfuric Acid Conditions.

Photoreduction of Cu ions to Cu metal by titanium(IV) oxide (TiO) was conducted in the presence of a silica-surfactant hybrid under sulfuric acid conditions. After irradiation, a dark-red color, reflections due to Cu metal in the X-ray diffraction pattern, and peaks due to Cu 2 and 2 in the X-ray photoelectron spectrum indicated the precipitation of Cu metal in the product. In addition, an increase in the Brunauer-Emmett-Teller specific surface area from 36 and 45 m/g for the silica-surfactant and TiO, respectively, to 591 m/g for the product, and a decrease in the intensity of the C-H stretching band in the Fourier-transform infra-red spectra implied the removal of surfactant during the reaction. These characteristics were never observed when TiO was used solely. Therefore, this study indicated that the photoreduction of Cu ions to Cu metal by TiO was facilitated under the sulfuric acid medium, where the surfactants extracted from silica-surfactant hybrids by protons in the acidic condition were successfully photo-oxidized by TiO. Thus, this study presents a new application of the conversion of a silica-surfactant hybrid into mesoporous silicas.