合金元素Nd对Pb-Ag阳极在H2SO4溶液中电化学行为的影响

采用循环伏安、线性扫描、电化学阻抗和环境扫描电镜对比研究了Pb-Ag和Pb-Ag-Nd阳极的阳极膜和析氧反应. 结果表明，合金元素Nd促进了Pb/PbO_n/PbSO₄ (1≤n<2)膜层的生长. 在高极化电位区间(高于1.20V (vs Hg/Hg₂SO₄/饱和K₂SO₄溶液))，Nd有利于低价铅的化合物(PbO_n，PbSO₄)向α-PbO₂和β-PbO₂转变. 此外，环境扫描电镜形貌和线性扫描分析证明Pb-Ag-Nd表面生成的阳极膜较Pb-Ag的阳极膜更厚且更致密. 因此，Pb-Ag-Nd阳极表面的阳极膜可以给合金基底提供更好的保护. 另一方面，电化学阻抗测试揭示了两种阳极的析氧反应均受中间产物的形成和吸附控制. Nd可以降低阳极膜/电解液界面处中间产物的吸附阻抗且增加中间产物的覆盖率，从而提高析氧反应活性. 综上所述，合金元素Nd可提高Pb-Ag阳极的耐腐蚀性，降低阳极电位进而起到节能降耗的作用.

Influence of Alloying Element Nd on the Electrochemical Behavior of Pb-Ag Anode in H2SO4 Solution

Anodic layers and oxygen evolution reaction (OER) of Pb-Ag and Pb-Ag-Nd anodes were investigated by cyclic voltammetry, linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and environmental scanning electron microscopy (ESEM). Alloying with Nd promoted the formation of Pb/PbO_n/PbSO₄ (1≤n<2). Nd facilitated the transformation of PbO_n and PbSO₄ to α-PbO₂ and β-PbO₂, at potential above 1.2 V vs Hg/Hg₂SO₄ (saturated K₂SO₄ solution). ESEM and LSV indicated that the anodic layer formed on the Pb-Ag-Nd anode was thicker and more compact than that formed on the Pb-Ag anode. Consequently, the anodic layer on the Pb-Ag-Nd anode could provide better protection for metallic substrates. EIS indicated that the OER was determined by the formation and adsorption of intermediates. Nd enhanced the OER reactivity, because of a smaller adsorption resistance and larger coverage of intermediates at the anodic layer/electrolyte interface. In summary, alloying with Nd can enhance the corrosion resistance and reduce the energy consumption of Pb-Ag anode due to lower anodic potential.