Effects of Architecture and Surface Chemistry of Three-Dimensionally Ordered Macroporous Carbon Solid Contacts on Performance of Ion-Selective Electrodes

摘要

The effects of the architecture and surface chemistry ofnthree-dimensionally ordered macroporous (3DOM) car-nbon solid contacts on the properties of ion-selectivenelectrodes (ISEs) were examined. Infiltration of the plas-nticized poly(vinyl chloride) (PVC) membrane into thenpores of the carbon created a large interfacial areanbetween the sensing membrane and the solid contact, asnshown by cryo-scanning electron microscopy (cryo-SEM)nand elemental analysis. This large interfacial area, alongnwith the high capacitance of the 3DOM carbon solidncontacts (as determined by cyclic voltammetry, chrono-npotentiometry, and electrochemical impedance spectros-ncopy) results in an excellent long-term stability of thenpotentiometric response, with drifts as low as 11.7 µVh. The comparison of 3DOM carbon solid contacts withnan untemplated carbon solid contact shows that the porenstructure is an essential feature for the excellent electrodenperformance. However, the surface chemistry of then3DOM carbon cannot be ignored. While there is nonevidence for an aqueous layer forming between the sens-ning membrane and unoxidized 3DOM carbon, electrodesnbased on oxidized 3DOM carbon exhibit potentiometricnresponses with the typical hysteresis indicative of a waternlayer. A comparison of the different techniques to char-nacterize the solid contacts confirms that constant-currentncharge discharge experiments offer an intriguing ap-nproach to assess the long-term stability of solid-contactnISEs but shows that their results need to be interpretednwith care.