Effect of photocatalytic reduction of carbon dioxide by N-Zr co-doped nano TiO.

Modified sol-gel method was adopted to prepare TiO, Zr-TiO and N/Zr-TiO composite catalyst. The as-synthesized photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunner- Emmet- Teller measurement and UV-Vis diffuse reflectance spectroscopy. And the photocatalytic performance toward CO reduction was evaluated under ultraviolet light. The catalyst particles were demonstrated in the nanometer level size. When N and Zr are co-doped, on the one hand, Ti can be replaced by Zr +, which leads to lattice distortion and inhibits electron-hole recombination. On the other hand, N enters into TiO lattice gap to form O-Ti-N bond structure, and partial Ti are reduced to Ti. Compared with pristine TiO, the specific surface area and the band gap of N/Zr-TiO were improved and reduced, respectively. The N and Zr synergistically contribute to the obviously strengthened absorption intensity in visible region, as well as significantly improved photocatalytic activity. In the gas phase reactor, when the calcination temperature was 550°C, 0.125N/0.25Zr-TiO composite performed the highest photocatalytic activity UV irradiation for 8 h, and the corresponding CH yield was 11.837 µmol/g, which was 87.8% higher than that of pristine TiO. For the visible light, the CH yield was 9.003 µmol/g after 8 h irradiation, which was 83.9% higher than that of pristine TiO.