期刊
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
卷 609, 期 2, 页码 147-154出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jelechem.2007.06.022
关键词
pH sensing; metal oxide electrodes; ion-selective pH UME; iridium oxide (IrOx); potential cycling; SECM; cast iron; oxygen reduction reaction
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 mu m) 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 2-12 pH with a super-Nernstian slope (-64 +/- 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 Fe(CN)(3-)(6) and Ru(NH3)(3+)(6) has little influence on the determination, however Ni2+ does produce an apparent pH shift. The application of these pHsensitive UMEs is demonstrated in imaging the pH changes due to the oxygen reduction reaction at the surface of a cast iron sample. (C) 2007 Elsevier B.V. All rights reserved.
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