Microparticle-based iridium oxide ultramicroelectrodes for pH sensing and imaging

详细信息    查看全文

• 作者：Emad El-Deen M. El-Giar ; David O. Wipf ; ^{wipf@ra.msstate.edu}
• 关键词：pH sensing ; Metal oxide electrodes ; Ion-selective pH UME ; Iridium oxide (IrOx) ; Potential cycling ; SECM ; Cast iron ; Oxygen reduction reaction
• 刊名：Journal of Electroanalytical Chemistry
• 出版年：2007
• 出版时间：1 November 2007
• 年：2007
• 卷：609
• 期：2
• 页码：147-154
• 全文大小：511 K

文摘

In this paper, we present a simple, relatively inexpensive, and reproducible method for the construction of iridium oxide (IrOx)-pH sensitive ultramicroelectrodes (UMEs). In this method, the pH sensing layer is based on an IrOx film formed by potential cycling of iridium microparticles (diameter <10 ¦Ìm) in 0.5 M H₂SO₄ at 3.0 V/s. The IrOx-pH microsensors prepared this way are chemically stable, uniform, and exhibit rapid and linear response to H⁺ over the range 2?2 pH with a super-Nernstian slope (?4 ¡À 7 mV/pH) at room temperature. The pH response is reproducible and remains stable over a period of 2 months. Coexistence of redox ions such as and has little influence on the determination, however Ni²⁺does produce an apparent pH shift. The application of these pH-sensitive UMEs is demonstrated in imaging the pH changes due to the oxygen reduction reaction at the surface of a cast iron sample.