Synthesis and investigation of photocatalytic and CO2 photoreductive properties of Ag/TiO2 nanowires

Silver nanoparticles with the diameter of 5 – 10 nm were successfully deposited on TiO2 nanowires by a facile and low-cost photoreduction method in alkaline solution under UV irradiation. The mutual coordination between light irradiation and NH4OH reduction gives rise to the formation and decoration of the Ag nanoparticles on the surface of TiO2 nanowires. The morphology, crystal structure, and optical properties of as-prepared products were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction, and UV-vis spectroscopy. Noticeably, the Ag nanoparticles play an important role to the transition from titanate to anatase and rutile phases in TiO2. The photocatalytic activity of all samples was evaluated by means of the degradation of methyl orange (MO) under the visible light irradiation. The results indicated that the presence of the Ag nanoparticle significantly improved the catalytic performance of TiO2 in the visible region, which could be attributed to the local surface plasmon resonance effect of the Ag. Nearly 99% MO was photo-decomposed within 90 minutes in the presence of Ag/TiO2, while there was only 70% MO degraded with the TiO2 catalyst. Furthermore, the Ag-decorated TiO2 nanowires also show good photo-conversion CO2 to methane with high selectivity. The amount of CH4 obtained over 1g Ag/TiO2 is approximately twice as much as that of TiO2