五氧化二铌电脱氧制备金属Nb的反应动力学

Kinetics of the electro-deoxidation of Nb_2O_5 for preparing niobium

采用交流阻抗谱技术研究了 Nb_2O_5的电脱氧机理．Nb_2O_5的电脱氧过程的交流阻抗谱的响应规律和中间产物表明, Nb_2O_5的电脱氧反应是分三步逐级进行的：第一步是 Nb_2O_5得到电子还原为低价氧化物 NbO_2,交流阻抗谱表现为高频半圆；第二步是 NbO_2得到电子还原为 NbO,交流阻抗谱出现第二个响应半圆；第三步是 NbO 还原为金属 Nb,交流阻抗谱在低频端出现第三个响应半圆．用等效电路拟和交流阻抗谱,得到了脱氧反应的电荷传递电阻及其活化能．电荷传递电阻和活化能均随着阴极电势的增加而降低．

A.C. impedance technique was used to investigate the mechanism of the electrodeoxidation of Nb2O5. The A.C. impedance spectra and the XRD pattern shown that the electrodeoxidation of Nb2O5 was conducted in three steps. The first step is the reduction of Nb2O5 to NbO2 corresponding to the impedance semicircle in the high frequency region; the second step is the reduction of NbO2 to NbO, which corresponds to the second impedance semicircle; the third step is the reduction of NbO to metal Nb, indicated by the impedance semicircle in the low frequency region. The charge transfer resistance and the activation energy were obtained by simulating the impedance spectra to equivalent circuits and decreased with increasing cathodic potential.