A pH Electrode Based on Melt-Oxidized Iridium Oxide

Fabrication and characterization of a novel potentiometric pH electrode based on melt-oxidized iridium oxide film is presented. The oxide film produced in a lithium carbonate melt has the composition of and shows high chemical stability. The electrode based on this oxide film exhibits very promising pH sensing performance, with an ideal Nernstian response in the tested pH range of 1 to 13. The potential response is fast, with a 90% response time obtained in less than 1 s for all pH changes. The open-circuit potential of the electrode is almost drift-free, with an average variation over time in a pH 6.6 solution as small as 0.1 mV/day. Furthermore, the potential/pH slopes and the apparent standard electrode potentials show excellent agreement among electrodes from the same batch. A comparison is made of the present electrode and those reported in the literature with respect to fabrication method and pH sensing characteristics. © 2001 The Electrochemical Society. All rights reserved.

[1]  J. Zemel,et al.  pH-sensitive sputtered iridium oxide films , 1981 .

[2]  Philippe Deniard,et al.  Structural and analytical characterization of an iridium oxide thin layer , 1993 .

[3]  B. Thirion,et al.  Chemical and electrochemical behaviour of copper species in the molten eutectic mixture Na2CO3 + K2CO3 at 800°C , 1995 .

[4]  Hiroki Yamamoto,et al.  Response of an Iridium Oxide pH-Sensor in Nonaqueous Solutions. Comparison with Other pH-Sensors , 1996 .

[5]  V. Plichon,et al.  Anodic electrodeposition of iridium oxide films , 1998 .

[6]  Yuichi Watanabe,et al.  Preparation and properties of electrochromic iridium oxide thin film by sol-gel process , 1999 .

[7]  F. Lévy,et al.  Thermal Stability of Sputtered Iridium Oxide Films , 1989 .

[8]  Patrick J. Kinlen,et al.  A solid-state pH sensor based on a Nafion-coated iridium oxide indicator electrode and a polymer-based silver chloride reference electrode , 1994 .

[9]  G. Janz,et al.  Corrosion of Platinum, Gold, Silver and Refractories in Molten Carbonates , 1963 .

[10]  J. Cox,et al.  Characterization of oxide films electrochemically deposited from solutions of palladium chloride and sodium hexachloroiridate , 1992 .

[11]  Wouter Olthuis,et al.  pH sensor properties of electrochemically grown iridium oxide , 1990 .

[12]  S. Gottesfeld,et al.  Electrochromism in Anodic Iridium Oxide Films II . pH Effects on Corrosion Stability and the Mechanism of Coloration and Bleaching , 1979 .

[13]  Michael J. Tarlov,et al.  Sputtered thin-film pH electrodes of platinum, palladium, ruthenium, and iridium oxides , 1995 .

[14]  M. Hitchman,et al.  Evaluation of iridium oxide electrodes formed by potential cycling as pH probes. , 1988, The Analyst.

[15]  R. Einerhand,et al.  pH Measurement in strong KOH solutions with a bismuth electrode , 1989 .

[16]  M. Neuman,et al.  A Palladium-palladium oxide miniature pH electrode. , 1980, Science.

[17]  H. Thirsk,et al.  EMF measurements of cells employing metal—metal oxide electrodes in aqueous chloride and sulphate electrolytes at temperatures between 25–250°C☆ , 1976 .

[18]  W. Grubb,et al.  Palladium-palladium oxide pH electrodes , 1980 .

[19]  PREPARATION OF AN OXIDIZED IRIDIUM ELECTRODE AND THE VARIATION OF ITS POTENTIAL WITH PH , 1984 .

[20]  P. Pickup,et al.  The Influence of the Aqueous Growth Medium on the Growth Rate, Composition, and Structure of Hydrous Iridium Oxide Films , 1988 .

[21]  M. Pourbaix.  Atlas of Electrochemical Equilibria in Aqueous Solutions , 1974 .

[22]  M. Madou.  Fundamentals of microfabrication , 1997 .

[23]  M. Hitchman,et al.  A field-induced poising technique for promoting convergence of standard electrode potential values of thermally oxidized iridium pH sensors. , 1992, Talanta.

[24]  Min Wang.  Potentiometric sensors for pH and carbon dioxide measurement , 2002 .

[25]  Corrosion , 1941, Science.

[26]  Agner Fog,et al.  Electronic semiconducting oxides as pH sensors , 1984 .

[27]  M. Rȩkas,et al.  Studies on the binary system Li2CO3–BaCO3 , 2001 .

[28]  S. Trasatti.  Physical electrochemistry of ceramic oxides , 2010 .

[29]  S. Ardizzone,et al.  Properties of thermally prepared iridium dioxide electrodes , 1981 .

[30]  Teruaki Katsube,et al.  “ETOX pH SENSOR” AS pH MEASURING ELECTRODE , 1991 .

[31]  L. Burke,et al.  A voltammetric investigation of the charge storage reactions of hydrous iridium oxide layers , 1984 .

[32]  S. Głąb,et al.  Polycrystalline and monocrystalline antimony, iridium and palladium as electrode material for pH-sensing electrodes. , 1986, Talanta.

[33]  Michael J. Tarlov,et al.  Mechanistic and response studies of iridium oxide pH sensors , 1990 .

[34]  J. Baur,et al.  Electrochemical deposition of iridium (IV) oxide from alkaline solutions of iridium(III) oxide , 1998 .

[35]  Huang,et al.  Electron paramagnetic resonance of a molecular defect in gamma -irradiated IrO2 single crystals. , 1989, Physical review. B, Condensed matter.

[36]  Peter Douglas,et al.  Novel thick-film pH sensors based on ruthenium dioxide-glass composites , 1995 .

[37]  M. Madou,et al.  Chemical Sensing With Solid State Devices , 1989 .

[38]  H. Grabke,et al.  Corrosion of iron base alloys and high alloy steels in the Li2CO3-K2CO3 eutectic mixture , 1997 .

[39]  B. Conway,et al.  Surface and bulk processes at oxidized iridium electrodes—II. Conductivity-switched behaviour of thick oxide films , 1983 .

[40]  M. Yuen,et al.  Electrically free-standing IrOitx thin film electrodes for high temprature, corrosive environment pH sensing , 1983 .

[41]  M. Hitchman,et al.  Potentiometric determination of proton activities in solutions containing hydrofluoric acid using thermally oxidized iridium electrodes , 1991 .

[42]  I. Uchida,et al.  Oxide electrodes in molten carbonates Part 1. Electrochemical behaviour of nickel in molten Li + K and Na + K carbonate eutectics , 1995 .

[43]  W. Cascio,et al.  Electrodeposited iridium oxide pH electrode for measurement of extracellular myocardial acidosis during acute ischemia. , 1998, Analytical chemistry.

[44]  Helmuth Galster,et al.  pH Measurement: Fundamentals, Methods, Applications, Instrumentation , 1991 .

[45]  G. Papeschi,et al.  Use of an iridium electrode for direct measurements of pI of proteins after isoelectric focusing in polyacrylamide gel. , 1976, Biochimica et biophysica acta.

[46]  Marc Madou,et al.  Electrochemical Measurements on Pt, Ir, and Ti Oxides as pH Probes , 1984 .

[47]  N. Kitamura,et al.  Electrochemically-deposited RuO2 films as pH sensors , 1993 .