Abstract:

A Pb-Zn coating was electroplated from methyisulfonic acid bath. The coating was then corroded by 10%H2SO4(volume fraction) solution to dissolve zinc. A porous Pb-Zn electrode was therefore successfully prepared. The Pb-Zn coating was composed of Pb(Fm3m) and Zn(P63/mmc). Electrochemical reduction characteristics of maleic acid(MA) on porous Pb-Zn and Pb electrodes were investigated by voltammetry, cathode polarization, chronocoulometry, and electrochemical impedance spectrum(EIS). As a result, MA was absorbed on the electrode surface, and then underwent irreversible electron-transfer reaction. The corresponding diffusion coefficients for MA in H2SO4 solution on a Pb and porous Pb-Zn electrode was 1.2×10-7 and 1.7×10-7 cm2/s, respectively. The apparent exchange current density(i0) of MA on a porous Pb-Zn electrode was steadier than that on a Pb electrode. The i0 of MA on the porous Pb-Zn electrode had a linear relationship with temperature in low temperature, and increased sharply above 50 ℃, while decreased rapidly when reached to 65 ℃. The best electrochemicalreduction temperature for MA on porous Pb-Zn electrode was 50~60 ℃. The catalytic activity of MA on porous Pb-Zn electrode was higher than that on lead electrode.

Key words: Porous Pb-Zn electrode, Maleic acid, Electro-reduction, succinic acid