The electrochemical reaction mechanism of CuCl2-NaCl weak acid solution was studied by the Tafel method and linear potential sweep voltammetry at room temperature. The exchange current densities at different concentration ratios of CuCl2-NaCl solution were obtained from their polarization curves and the coordination number of the electrochemical reduction complex was calculated from electrochemical reaction order method. The electrochemical reduction on Pt electrode was further studied by linear potential sweep voltammetry. Finally, the concentration of the electrochemical reduction complex ion was calculated when the procedure was reversed. The results were shown that [ CuCl ]+ is the main cupric chloride complex in solution and the one for electrochemical reduction on Pt electrode. Two one-electron reduction steps of the copper chloride complex were observed on the surface of the Pt electrode. The first step was a one-electron-transfer reversible reduction process. The electrochemical reaction orders of [ CuCl ]+ and Cu in the system were both level one. In 4. 000 mol/L NaCl + 0. 100 mol/L CuCl2 solution, the concentration of the electrochemical reduction reactant ( [ CuCl ]+ ) was 0. 086 mol/L. The results provided important experimental evidences for electrochemical reduction mechanism of Cu + in aqueous solutions with highly concentrated chloride ions.This work can also be used as a reference for electrochemical analysis of dissolved metal complex in the fields ofmetallurgy, geology, geochemistry in the future.%运用Tafel极化曲线和线性电势扫描法研究了常温弱酸性CuCl2-NaCl溶液中铜氯络合物体系的电化学放电机理.通过测量不同浓度配比的CuCl2-NaCl溶液的极化曲线得到各自的交换电流密度,然后根据电化学反应级数法计算直接在电极上放电的Cu(Ⅱ)-Cl络合物的配位数.并且运用线性电势扫描法进一步研究了此络合物在铂电极上的还原反应,在体系可逆的情况下计算得到其发生放电反应的离子浓度.结果表明:溶液中存在的主要络离子是[CuCl]+,在铂电极上发生电化学反应的铜络离子是[CuCl]+.铜氯络离子在铂电极上的还原反应分两步进行,其中第一步为可逆的单电子还原过程,体系中[CuCl]+和Cu的电化学反应级数均为一级;4.000 mol/L NaCl-0.100 mol/L CuCl2溶液体系中发生放电反应的[CuCl]+的浓度为0.086 mol/L.研究结果为目前学术界存在广泛分歧的Cu2+在高浓度氯离子溶液中的放电机理提供了重要的实验依据,同时对未来湿法冶金、地质和地球化学等领域中溶解态金属络合物的电化学分析具有一定的借鉴作用.
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