Photoelectrochemical Behavior of n-Type TiO2 and Other Semiconductor Electrodes in Acetonitrile Solutions Containing Various Aromatic Amines

Abstract

Abstract The electrode behavior of n-type TiO2 in acetonitrile solutions containing one of a variety of aromatic amines under illumination has been investigated. The onset potential of the anodic photocurrent leading to the oxidation of the amines changed from the most negative −0.51 V vs. SCE for N,N,N′,N′-tetramethyl-p-phenylenediamine to the least negative −0.27 V for aniline. These values parallel the change of the flat band potential by the amine and become more negative as the ionization potential of the amine decreases. The influence of the amine on the flat band potentials of ZnO, CdS, and GaP was also studied and found to be much less than in the case of TiO2. From these results, the reason for the change of the flat band potential in the case of TiO2 is attributed to a specific charge transfer interaction between the semiconductor and the amine.