铜电极表面硝酸盐电化学还原机理研究

目前地表水受到严重氮污染,其中以离子态硝酸盐为主。实验利用线性扫描伏安法与恒电位电解法,研究了铜电极表面硝酸盐电化学还原产物与反应机理。结果表明,硝酸盐的还原产物取决于外加电位。铜电极上硝酸盐的吸附从-0.6 V(以汞/氧化汞电极为参比)开始,-0.8~-1.0 V之间硝酸盐还原为亚硝酸盐,该反应为整个硝酸盐还原过程的速控步骤;理想产物氮气主要在-1.0~-1.2 V之间生成;-1.2~-1.4 V之间主要还原产物为氨氮。随着电势降低,反应速率增大,对副产物氨氮的选择性也升高。

Study on electrochemical reduction mechanism of nitrate on surface of copper electrode

The surface water is frequently contaminated by nitrogen which is mainly in the form of nitrate nowadays.This experiment used the methods of linear sweep voltammetry and potentiostatic electrolysis to study the reduction product and mechanism of nitrate on surface of copper electrode.Experimental results showed that the electroreduction product of nitrate strongly depends on the applied potential. The reduction of nitrate on copper electrode started from a potential ca. -0.6 V vs. Hg/HgO, followed by a reduction to nitrite between -0.8 V and -1.0 V is sub-nitrate.The reaction is identified as the rate-determining step of the nitrate electroreduction process.Between -1.0 V and -1.2 V, the nitrogen as the ideal product is produced, and finally converts ammonia at potential between -1.2 V and -1.4 V. The reaction rate increases and the selectivity to ammonia also rises with the decrease of electric potential.