马来酸在多孔铅锌电极上电还原特性

Electrochemical-reduction Characteristics of Maleic Acid on a Porous Pb-Zn Electrode

在甲磺酸镀液中电沉积Pb-Zn镀层,然后用体积分数为10%的H2SO4腐蚀镀层,使镀层中的Zn脱溶,成功得到多孔Pb-Zn电极,该镀层由铅(Fm3m)和锌(P63/mmc)的混合物组成。采用循环伏安、阴极极化、计时电量及电化学阻抗等方法,研究了马来酸在多孔Pb-Zn电极和Pb电极上的电化学还原特性。结果表明,马来酸在电极上先发生吸附,然后进行不可逆电子传递反应;马来酸在Pb电极和多孔Pb-Zn电极上还原的扩散系数分别为1.2×10-7和1.7×10-7 cm2/s;随着温度升高,马来酸在Pb电极上表观交换电流密度稳定性不如多孔Pb-Zn电极,多孔Pb-Zn电极上马来酸在低温处i0与温度呈线性关系,从50℃开始,i0急剧增加,至65℃,i0迅速下降,其在多孔Pb-Zn电极上电还原在50～60℃最好。马来酸在多孔Pb-Zn电极比相应的Pb电极上具有更高的电催化活性。

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（P663/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.