Molecular Design Of Visible Light Responsing Photocatalysts Of Metal Oxide Composites

TiO₂ has been one of the most popular photocatalytic materials due to its outstanding chemicophysical stability, low-cost and innocuous. However, the band gap of TiO₂ is so wide that it is only activated under ultraviolet light irradiation.So the solar energy can't be used efficiently. Besides, the photogenerated carriers are easily recombinated. Doping with transition metals has been proved to be an effective way.In this work, we introduced the development and application of computational simulation methods that applied in materials research field, such as Density Functional Theory(DFT), Local Density Approximation(LDA), Generalized Gradient Approximation (GGA), and used the CASTEP package in materials studio software to establish a mathematic model of TiO₂ (anatese) doped with various metals and ABO₃ complex oxides'supercells.Then the first principle method was employed.We also explored the band structure and density of states of perovskite-type metal oxides. The results indicated that the VB and CB positions of CrTiO₃ were better for absorbing visible light, so we further calculated the Bi/ CrTiO₃ composite. However, the band gap of Bi doped CrTiO₃ increased and decreased the efficiency of photocatalysis.In addition, combining the formula in the literature with the calculated values of band gaps and the band edge position, we designed a Cu-doped TiO₂ whose better ability met the requirments of CO₂ photocatalytic reduction in the redox of the photocatalytic CO₂, while bands gap was reduced either (2.2013Ev) for full use of sun light.At the end, we researched the catalytic mechanism, and experimentally proved CuO/TiO₂ photocatalytic effect in reduction of CO₂.