银在氢氧化钠溶液中的电化学行为

摘要

The electrochemical behaviors of silver in NaOH solution were investigated via cyclic voltammetry, anodic polarization, mass gain and scanning electron microscope. The results reveal that the current density peak of Ag2O forms and follows with the formation of AgO during the anodic polarization. Anodic current density of silver decreases sharply to a stable value, and silver oxide with the same size are formed on silver’s surface under potentiostatic polarization in the three NaOH solutions. The higher the NaOH concentration is, the denser the silver oxides distribute on the surface of silver. At the same potential for the potentiodynamic polarization curves of silver, the anodic current density of silver increases with NaOH concentration increasing. Mass gain of the potentiodynamic anodic polarized silver increases with NaOH concentration as well. The morphologies of the potentiodynamic anodic polarized silver shows that the corrosion products accumulate more severe and there are more micro­cracks on the surface of silver polarized with higher NaOH concentration than with lower NaOH concentration. The micro­cracks provide channels for ion transport, which is essential for further corrosion of silver in NaOH solution, through the corrosion products.%通过设计三电极电化学系统，采用循环伏安、动电位阳极极化以及恒电位阳极极化方法研究了银在不同氢氧化钠溶液的电化学行为。结果表明：银在NaOH溶液中，循环伏安和动电位阳极极化正向扫描中出现Ag2O和AgO的氧化峰。随着NaOH浓度的增加，在相同电极电位条件下，阳极电流密度逐渐增加，极化后银的腐蚀增质也随之增加；极化后样品表面的腐蚀产物聚集更为严重，出现较多的孔洞和微裂纹，从而为电解质溶液和基体之间的物质传输提供了更多通道，加速了银的电化学腐蚀进程。