CAJ | 학술논문

采用循环伏安法(CV)和电化学交流阻抗法(EIS)，研究不同柠檬酸盐浓度和pH下钴的电化学还原过程。结果表明：在组成为0.05 mol/L CoSO4·5H2O、0.20 mol/L Na2SO4和0~0.40 mol/L C6H5O7Na3·2H2O，pH为3~9的溶液中，二价钴以游离 Co2+离子和[Co(C6H5O7)]配合物两种形态存在，并在电极表面被还原。溶液的 pH 对钴的电化学还原过程有显著的影响。当柠檬酸盐溶液的pH为3时，钴主要以游离Co2+离子的形态被还原；当溶液为弱酸性(pH=4~6)时，钴主要以[Co(C6H5O7)]-的形态被还原为 Co0，还原过程分两步进行，中间产物在电极表面发生吸附；当柠檬酸盐水溶液的pH大于7时，形成的柠檬酸钴配合物主要是[Co(C6H5O7)]-和[Co(C6H4O7)]2-，这两种配合物非常稳定，其还原电位负于溶液的析氢电位，因此难以从该溶液中还原得到Co0。
채용순배복안법(CV)화전화학교류조항법(EIS)，연구불동저몽산염농도화pH하고적전화학환원과정。결과표명：재조성위0.05 mol/L CoSO4·5H2O、0.20 mol/L Na2SO4화0~0.40 mol/L C6H5O7Na3·2H2O，pH위3~9적용액중，이개고이유리 Co2+리자화[Co(C6H5O7)]배합물량충형태존재，병재전겁표면피환원。용액적 pH 대고적전화학환원과정유현저적영향。당저몽산염용액적pH위3시，고주요이유리Co2+리자적형태피환원；당용액위약산성(pH=4~6)시，고주요이[Co(C6H5O7)]-적형태피환원위 Co0，환원과정분량보진행，중간산물재전겁표면발생흡부；당저몽산염수용액적pH대우7시，형성적저몽산고배합물주요시[Co(C6H5O7)]-화[Co(C6H4O7)]2-，저량충배합물비상은정，기환원전위부우용액적석경전위，인차난이종해용액중환원득도Co0。
Effects of citrate concentration and pH on the electrochemical reduction process of Co(II) were investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results show that Co(II) is reduced into two species which are free Co2+ and [Co(C6H6O7)] in the solution composed of 0.05 mol/L CoSO4·5H2O, 0.20 mol/L Na2SO4 and 0-0.40 mol/L C6H5O7Na3·2H2O in the pH range of 3-9. The reduction behavior depends on the pH of the solution. Co(II) is mainly reduced into the form of free Co2+at pH 3 and into the form of [Co(C6H6O7)] at the pH range of 4-6 in citrate solution. The [Co(C6H6O7)] is first reduced to an intermediate state and then to Co0. Adsorption of the intermediate state exists on the surface of the electrode. Co(II) is difficult to be reduced in the solution with the pH above 7, because the existing Co(II)-citrate complex species [Co(C6H5O7)]-and [Co(C6H4O7)]2-are more difficult to be reduced than the hydrogen ion.