Photocatalytic Degradation of Gaseous Benzene on Photodeposited Ag-TiO2 Nanoparticles

TiO2 nanoparticles were synthesized by a simple sol-gel method using titanium isopropoxide as the precursor. Ag-TiO2 nanoparticles were prepared by the photoreduction of AgNO3 on TiO2 under UV light irradiation. The structural and morphological properties of the Ag-TiO2 nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. The optical properties of TiO2 and photodeposited Ag-TiO2 were analyzed by UV-Vis spectrophotometry. The photocatalytic properties of the TiO2 and photodeposited Ag-TiO2 nanoparticles were evaluated by the photocatalytic degradation of gaseous benzene under UV and visible light irradiation. The residual concentration of benzene was monitored by gas chromatography to estimate the rate of photolysis under UV (lambda = 365 nm) and visible (lambda >= 410 nm) light. The photodeposited Ag-TiO2 nanoparticles exhibited more efficient photocatalytic activity towards the photodegradation of benzene than bare TiO2 under visible light irradiation. The enhanced photocatalytic activity of Ag-TiO2 nanoparticles was attributed to the decrease in the activation energy and the existence of Ag in the TiO2 host lattice, which increases the absorption capacity in the visible region by acting as electron trappers to promote the charge separation of photoinduced electrons (e(-)) and holes (h(+)). The Ag-TiO2 nanoparticles have environmentally benign photocatalytic activity using visible light and can have environmental cleaning applications.