基于扫描电化学显微镜产生/收集和反馈模式研究纯Mg腐蚀行为

Since electrochemical impedance spectroscopy, polarization curve and hydrogen collection were the main technologies for corrosion research of Mg and its alloy. However, those methods only provide the meaninformation of entire surface of corrosion electrode. In this work, H2 evolution and active sites of pure Mg from localized sites (point, line and surface) in NaCl and Na2SO4 solution based on generation/collection and feedback modes of scanning electrochemical microscopy (SECM) were studied. The results indicate that both cathodic and anodic polarization are in favor of H2 evolution in NaCl and Na2SO4 solution, which is well in line with the negative difference effect by the classical H2 collection, but the SECM results show that the H2 evolution in localized sites is not uniform and stable. The H2 evolution rate increases with NaCl concentration increasing, which is opposite in Na2SO4 solution. The higher NaCl concentration, anodic polarization and lower pH value accelerate the formation of active sites on pure Mg surface.