Activity and selectivity of Cu and Ni Doped TiO2in the photocatalytic reduction of CO2with H2O under UV-light irradiation

Abstract

Photocatalysis has been found to be an effective method to convert CO2into valuable products. To explore the selectivity and photocatalytic activity of transition metal doped TiO2catalysts for the reduction of CO2, a series of Cu and Ni (0.5-7.0 wt. %) doped TiO2nanoparticles were prepared by means of a hydrolysis method. Photocatalytic experiments were conducted under irradiation from Hg lamps in a CO2/ NaOH aqueous solution. The results indicate that the photoreduction of CO2with water, catalyzed by Cu-TiO2and Ni-TiO2, can yield CO, HCHO, CH3OH and CH4. Methane was identified as the major products using Cu-TiO2or Ni-TiO2. In addition, Ni-TiO2shows greater CO2conversion in comparison with Cu-TiO2. With the help of X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett- Teller measurements, transmission electron microscopy and UV-visible absorption spectra, it is concluded that both the adsorption and dissociation of CO2and improvement of the photocatalytic activity by forming a n-p junction and providing matching band potentials, play a crucial role in determining the types and amounts of photoproducts.