Adsorption and reduction of palladium–dimethylglyoxime complex

The voltammetric reduction of PdII(DMGH)2 preadsorbed on mercury in 0.2 M acetic/acetate buffer (pH 4.85) was studied. Two adsorbed surface stages could be distinguished: while a submonolayer is present molecules adsorb parallel to the electrode, but at high surface concentration perpendicular interactions between adsorbed molecules lead to bilayer or even multilayer formation. The surface charge value obtained for the reduction of a virtual monolayer is QM = 38 μC cm−2. The electrochemical behaviour of adsorbed species under submonolayer coverage is explained in terms of an ErCi surface reaction scheme and a rate expression that takes into account attractive forces between the adsorbed reactant complex molecules.