Laboratório Interdisciplinar de Eletroquímica e Cerâmica (LIEC), Federal University of São Carlos (UFSCar), Chemistry Dept., PO Box: 676, CEP: 13.565-905, São Carlos, SP, Brazil.
Institute of Chemistry of São Carlos, University of São Paulo (USP), PO Box: 780, CEP: 13560-970, São Carlos, SP, Brazil.
Anal Chim Acta. 2015 Oct 15;897:17-23. doi: 10.1016/j.aca.2015.09.047. Epub 2015 Oct 8.
There are some electrocatalytic reactions in which the key parameter explaining their behavior is a local change in pH. Therefore, it is of utter importance to develop an electrode that could quantify this parameter in situ, but also be customizable to be used in different systems. The purpose of this work is to build a versatile rotating ring/disc electrode (RRDE) with IrOx deposited on a glass tube as a ring and any kind of material as disc. As the IrOx is sensitive to pH variation, the reactions promoted on the disc can trigger proportional pH shifts on the ring. In such assembly, the IrOx ring presents a fast response time even during the pH transients due to the small thickness of the ring (approximately 10 μm), which enables the detection of interfacial pH changes. The ring electrode was tested toward the interfacial pH shift observed during the electrolytic reduction of water on the disc and also characterized by acid-base titration to determine the response time. As the main conclusions, fast response and durable RRDE were obtained, and this assembly could be used to revisit many electrocatalytic reactions in order to test the importance of local pH on the process.
有些电催化反应的关键参数是局部 pH 值的变化。因此，开发一种能够现场定量测量该参数的电极，并能够针对不同系统进行定制，是非常重要的。本工作的目的是构建一种多功能的旋转环/盘电极（RRDE），将 IrOx 沉积在玻璃管的环上，并使用任何种类的材料作为盘。由于 IrOx 对 pH 值的变化敏感，盘上的反应可以引发环上的比例 pH 值变化。在这种组件中，由于环的厚度约为 10 μm，因此 IrOx 环具有快速的响应时间，即使在 pH 瞬变期间也能如此，从而能够检测到界面 pH 值的变化。对盘上水电解还原过程中观察到的界面 pH 值变化，用环电极进行了测试，并通过酸碱滴定进行了特性表征，以确定响应时间。作为主要结论，获得了快速响应和耐用的 RRDE，该组件可用于重新研究许多电催化反应，以检验局部 pH 值对该过程的重要性。
