A computational study on the adsorption and ring cleavage of para-chlorophenol on anatase TiO2 surface

In this work, a computational technique based on semiempirical SCF MO method MSINDO, has been used for investigation of the adsorption and photocleavage of para-chlorophenol (p-CP) molecule on the anatase TiO2 (0 0 1) and (1 0 0) surfaces. The surfaces have been modeled with two saturated clusters Ti21O58H32 and Ti36O90H36. The optimization of the perpendicular conformation of p-CP molecule relative to the anatase TiO2 (1 0 0) surface, has resulted in a linkage of the molecule to the surface titanium atom via phenolic oxygen atom. We studied the aromatic ring cleavage by singlet oxygen (1O2) and superoxide radical anion (O2
- -) and accordingly, relevant mechanisms are suggested. The results reveal that the ring opening path of p-CP molecule on TiO2 (1 0 0) surface, following the single electron transfer/O2
- - mechanism, is energetically more favourable than the 1O2/dioxetane mechanism.