Theoretical study of adsorption characteristics and the environmental influence for metronidazole on photocatalytic TiO2 anatase surfaces

The adsorption characteristics of metronidazole on anatase TiO2(101) and (001) surfaces were studied by density functional theory (DFT). The adsorption structure of metronidazole on anatase TiO2(101) and (001) surfaces has been optimized under vacuum, water, acidic, and alkaline conditions, respectively. The optimum adsorption site, adsorption energy, and electronic structure of the stable adsorption model were calculated. The adsorption characteristics of metronidazole on two different surfaces of TiO2 were studied under acidic and alkaline conditions. Our calculated results found that the adsorption energy range is -0.95 -3.11eV on the TiO2 (101) surface, and the adsorption energy range is -0.84 -3.29eV on the TiO2 (001) surface. The adsorption wavelengths of electron transition between valence band and conduction band of metronidazole on the anatase TiO2(101) surface is in the range of visible wavelength, indicating that the TiO2(101) surface can effectively utilize visible light. However, the photocatalytic effect of the TiO2(001) surface is greatly affected by the environment. The results reveal the adsorption characteristics and the environmental influence for metronidazole on photocatalytic anatase TiO2 surfaces.