Charge exchange between TiO2 and a polyfunctional chemisorbed molecule – the involvement of electrophilic groups

A chemisorbed polyfunctional molecule containing both a S atom and a Cl atom, (2-chloroethylethyl sulfide, 2-CEES) is able to abstract electrons which reside near the bottom of the conduction band in TiO2. By using analogous model compounds containing either the S moiety or the Cl moiety, it is found that electron transfer from TiO2 occurs only into the molecule containing the Cl moiety. This suggests that a specific electron transfer pathway involving the Cl atom is involved in the electron transfer interaction of 2-CEES with TiO2. Small coverages of adsorbed electron acceptor molecules are found to cause electron depletion of individual TiO2 crystallites.