Photocatalytic reduction of CO2 to hydrocarbons using AgBr/TiO2 nanocomposites under visible light

Urgent development of effective and low-cost technologies for reduction CO2 is needed to address global warming caused by atmospheric CO2 and the depletion of fossil fuels. In this investigation, an effective photocatalytic reduction of CO2 using AgBr/TiO2 photocatalyst under visible light (λ > 420 nm) was studied. The nanostructured AgBr/TiO2 photocatalyst was prepared by the deposition-precipitation method in the presence of cetyltrimethylammonium bromide (CTAB), and characterized by X-ray diffraction (XRD), diffuse reflectance spectra (DRS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their photocatalytic activities were evaluated by the reduction yield in the presence of CO2 and water. The experiment results showed that 23.2% AgBr/TiO2 had relatively high reduction yields under visible-light irradiation for 5 h, with a methane yield of 128.56, methanol yield of 77.87, ethanol yield of 13.28, and CO yield of 32.14 μmol g−1, respectively. The highly efficiently photocatalytic activities of AgBr/TiO2 in the reduction process of CO2 is attributed to its strong absorption in the visible-light region. In addition, it was found that AgBr/TiO2 photocatalyst was stable in the repeated uses under visible light irradiation, due to the transfer of photoexcited electrons from the conduction band of well-dispersed AgBr to that of TiO2.