Voltammetric studies of silane-modified SnO2 surfaces in selected aqueous and non-aqueous media

Voltammetric studies in selected aqueous and non-aqueous media were conducted for a series of silane-modified SnO₂ electrodes which had been further modified with a variety of metal phthalocyanines and metal cations. It is shown that tetrasulfonated, transitionmetal phthalocyanines can be both adsorbed and covalently attached to silane-modified surfaces where the silane has a coordinating ligand functionality such as a primary or secondary amine. It is further shown that the presence of the silane on the SnO₂ surface causes the appearance of a reversible voltammetric process following exposure of the surface to solution cation species. This reversible voltammetric wave is hypothesized to be due to the reduction of a surface bound Sn(IV) species to Sn(II) in a strongly hydroxylated environment.