Electron transfer rates on electrodes containing surface bonded molecules

The presence of covalently attached alkylsilyl derivatives on SnO2 electrode surfaces is found to render the electrochemical reactions of phenothiazine and benzoquinone in acetonitrile quasi-reversible. The magnitude of this effect is estimated for various silyl derivatives by comparing the heterogeneous standard rate, constants, ks, obtained by applying Nicholson's treatment to the measured cyclic voltammograms. The presence of the surface groups reduces the reaction rate by several orders of magnitude. © 1979 Elsevier Sequoia S.A.