LINEAR SWEEP AND CYCLIC VOLTAMMETRY FOR METAL-DEPOSITION AT SOLID ANDMERCURY MICROELECTRODES FROM SOLUTIONS WITH AND WITHOUT SUPPORTING ELECTROLYTE

The experimental behaviour under linear sweep and cyclic voltammetry a t low scan rates of the reduction of pb(2+) and Cd2+ at solid and merc ury microelectrodes is reported in the presence and in the absence of supporting electrolyte. The major effects observed on decreasing the c oncentration of supporting electrolyte are an increase in the steady-s tate limiting current and more drawn out curves during the direct scan , broader and asymmetric stripping peaks on the reverse scan. These ef fects are rationalized in terms of the contributions of migration asso ciated with diffusion in the mass transport and ohmic polarization whi ch adds to concentration polarization when the concentration of suppor ting electrolyte is decreased. The experimental results are also compa red with theoretical predictions.