Adsorption characteristics and degradation mechanism of DMZ on photocatalyst TiO<sub>2</sub> surface: a density functional theoretical study

Abstract

In this article, the adsorption and degradation mechanism of dimetridazole (DMZ) on anatase TiO2(101) and (001) crystal surfaces has been studied by density functional theory. The adsorption stability of DMZ on anatase surface was studied under vacuum and neutral water solvents. The most stable adsorption configuration was optimized by theoretical analysis. It was found that DMZ can be adsorbed on photocatalyst TiO2 surface under two conditions. The hydrogen bond produced in the adsorption process can enhance the stability of the adsorption structure. The stable adsorption configuration makes the C–N bond length of DMZ longer, which is conducive to the ring opening degradation reaction. We also studied the mechanism of ring opening degradation of DMZ on two crystal planes of anatase TiO2. It was found that the reaction activation energy of the degrading reaction on TiO2(101) crystal surface is very high, and the ring opening reaction is difficult to occur. On the (001) crystal surface, the opening of DMZ can be carried out under the condition of thermal reaction. We studied the effect of the water solvation on the degradation reaction. It was found that the activation energies of DMZ on the anatase TiO2 surface was reduced, indicating that the solvent conditions could promote the degradation reaction.