Photocatalytic Reduction of CO2 Over Sol-Gel Derived Copper-Doped Titania Catalysts

Abstract

Different doping concentration of copper-doped titania was synthesized by sol-gel method, and the samples were characterized by X-ray diffraction (XRD); Field emission scanning electron microscope (FSEM-EDX); Specific surface area and Pore size analyzer (BET); Thermo gravimetric-differential thermal analyzer (TG-DTA) respectively. The photocatalytic reduction of CO2 experiments was carried out in a photocatalytic reactor. CO2 was discharged into a quartz reactor with catalyst suspended in NaHCO3 solution, and illuminated under UV irradiation at the wavelength of 253.7 nm for 10 h continuously. The results confirmed that in the copper modified TiO2 samples, the crystalline form of TiO2 exists as anatase; only on the high CuO loading sample (>10%), the CuO peaks appears obviously; the grain size of all the sol-gel derived CuO-TiO2 samples were nearly 30 nm, and the copper particles were consistent and dispersed on the surface of TiO2. CO2 can be reduced into methanol in the presence of NaHCO3 solution over CuO-TiO2 catalyst. The doping concentration of 5% CuO-TiO2 performed best catalytic effect, with the methanol yield of 27 mg (g-cata)−1 in 10 h. With increasing reaction time, yield of methanol was promoted.