Novel dual Pt-Pt/IrOx ultramicroelectrode for pH imaging using SECM in both potentiometric and amperometric modes
Novel dual Pt-Pt/IrOx ultramicroelectrode for pH imaging using SECM in both potentiometric and amperometric modes
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新型双 Pt-Pt/IrOx 超微电极，在电位和电流模式下使用 SECM 进行 pH 成像
DOI：
10.1016/j.elecom.2018.01.018
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发表时间：
2018
影响因子：
5.4
通讯作者：
Cao Fahe
中科院分区：
文献类型：
--
作者：
Zhu Zejie;Ye Zhenni;Zhang Qinhao;Zhang Jianqing;Cao Fahe
电位扫描电化学显微镜（SECM）允许使用离子选择性超微电极（UME）作为扫描探针在微米和亚微米尺度上绘制电极/电解质界面处的pH分布。然而，这种技术缺乏尖端到基板距离的精确控制。在这里，我们提出了一种新的双Pt-Pt/IrOxUME的316 L不锈钢（316 L-SS）腐蚀过程的局部原位pH可视化与精确的尖端-基板的距离控制使用电流和电位SECM模式。基于COMSOL的模拟和实验方法曲线获得与此双UME配置被用来精确地建立尖端-衬底距离。当探针配置与相同pH的本体电解质一起使用时，对于较小的尖端-基底分离观察到更高的pH值。此外，在腐蚀过程中，由于316 L-SS的局部腐蚀和再钝化，在垂直尖端-基底距离为12 μm处观察到局部阳极和阴极区的形成、消失和再生。
Potentiometric Scanning Electrochemical Microscopy (SECM) allows the pH distribution at electrode/electrolyte interfaces to be mapped at the micrometer and submicrometer scale using ion-selective ultramicroelectrodes (UMEs) as scanning probes. However, this technique lacks precise control of the tip-to-substrate distance. Herein we propose a novel dual Pt-Pt/IrOxUME for local in situ pH visualization of 316L stainless steel (316L-SS) corrosion processes with precise tip–substrate distance control using both amperometric and potentiometric SECM modes. Simulations based on COMSOL and experimental approach curves obtained with this dual UME configuration are used to precisely establish the tip–substrate distance. Higher pH values were observed for smaller tip–substrate separations when this probe configuration is used with bulk electrolyte of the same pH. Furthermore, during the corrosion process local anodic and cathodic zones were observed to form, disappear and regenerate at a vertical tip–substrate distance of 12 μm as a result of the localized corrosion and repassivation of 316L-SS.