CHARACTERIZATION OF SURFACE-CHARGE OF METAL-OXIDES BY ADSORPTION OF TCNQ

Zeta potentials of metal oxides such as alumina and titania by adsorption of 7,7,8,8-tetracyanoquinodimethane (TCNQ) from organic solvents were measured. The zeta potentials of their oxides in organic solvents only were decreased as follows: acetonitrile > ethyl acetate > 1,4-dioxane. Further, the zeta potentials decreased with increasing adsorbed amount of TCNQ and concentration of TCNQ anion radicals formed as a result of electron transfer from oxide surface to TCNQ. The mechanism of charge origin for these systems was discussed. © 1991.