Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Anal Chem. 2010 Jan 15;82(2):680-8. doi: 10.1021/ac902222n.
The effects of the architecture and surface chemistry of three-dimensionally ordered macroporous (3DOM) carbon solid contacts on the properties of ion-selective electrodes (ISEs) were examined. Infiltration of the plasticized poly(vinyl chloride) (PVC) membrane into the pores of the carbon created a large interfacial area between the sensing membrane and the solid contact, as shown by cryo-scanning electron microscopy (cryo-SEM) and elemental analysis. This large interfacial area, along with the high capacitance of the 3DOM carbon solid contacts (as determined by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy) results in an excellent long-term stability of the potentiometric response, with drifts as low as 11.7 muV/h. The comparison of 3DOM carbon solid contacts with an untemplated carbon solid contact shows that the pore structure is an essential feature for the excellent electrode performance. However, the surface chemistry of the 3DOM carbon cannot be ignored. While there is no evidence for an aqueous layer forming between the sensing membrane and unoxidized 3DOM carbon, electrodes based on oxidized 3DOM carbon exhibit potentiometric responses with the typical hysteresis indicative of a water layer. A comparison of the different techniques to characterize the solid contacts confirms that constant-current charge-discharge experiments offer an intriguing approach to assess the long-term stability of solid-contact ISEs but shows that their results need to be interpreted with care.
研究了三维有序大孔（3DOM）碳固体接触的结构和表面化学对离子选择性电极（ISE）性能的影响。通过冷冻扫描电子显微镜（cryo-SEM）和元素分析表明，将增塑聚氯乙烯（PVC）膜渗透到碳孔中会在传感膜和固体接触之间形成大的界面面积。这种大的界面面积，再加上 3DOM 碳固体接触的高电容（通过循环伏安法、恒电流计时电位法和电化学阻抗谱法确定），导致了电位响应的优异长期稳定性，漂移低至 11.7 μV/h。与无模板碳固体接触相比，3DOM 碳固体接触的比较表明，孔结构是优异电极性能的重要特征。然而，3DOM 碳的表面化学也不容忽视。虽然在传感膜和未氧化的 3DOM 碳之间没有形成水层的证据，但基于氧化 3DOM 碳的电极表现出具有典型滞后的电位响应，表明存在水层。对不同技术来表征固体接触的比较证实，恒流充放电实验提供了一种评估固体接触 ISE 长期稳定性的有趣方法，但也表明需要谨慎解释其结果。
