The Influences of Quenching Times on the Property of Thermal Oxidized Iridium pH Sensor

Huang, Feifei; Jin, Ying; Wen, Liping; Mu, Daobin; Cui, Mengmeng

doi:10.1149/05012.0237ecst

Cited by 3 publications

(8 citation statements)

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“…According to this criterion, the time period needed for potential stabilization is defined as the response time of the electrode. 32 Figs. 3a-3c show error bar plots of the response time of IrO x pH electrodes fabricated by 1∼3 times of H&Q at the three examined temperatures in pH = 1∼13 buffer solutions.…”

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

“…14,31 Among which, the electrode produced by thermal oxidation exhibited excellent overall performance, including wide E-pH relationship range, fast response time and long term stability. [32][33][34][35][36] Wang et al developed carbonate melt oxidation to coat Ir through the oxidation of Ir wires in a carbonate melt at 870 • C for 5 hours. 31 Hitchman et al produced IrO x -electrodes by direct thermal oxidation in air at 800 • C. 34 Both surface films of fabricated by the above conditions showed obvious cracks.…”

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The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

Huang¹,

Wan²,

Jin³

et al. 2017

J. Electrochem. Soc.

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The present work demonstrated the effects of isothermal oxidation temperature (750 • C∼870 • C) and water quenching cycle times (1∼3) on properties of IrO x pH electrodes. Property tests of the fabricated electrodes showed that electrodes developed by 800 • C isothermal heating and water quenching for 3 times (H&Q 3) had excellent near Nernst E-pH relationship, relatively faster response rate and the minimum potential drift in long-term stability test. Surface and cross-section morphologies, confocal laser scanning microscopy, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the electrodes to explore the reason for their excellent properties. Surface morphology showed that the iridium oxide film (IROF) made by H&Q 3 at 800 • C had larger surface roughness, and well-defined homogeneous dense inner layer and loose porous outer layer. Besides, it had the minimum reaction resistance in both acid and alkaline buffers, and contained more effective compositions compared to electrodes fabricated by other conditions. Thus H&Q 3 at 800 • C was suggested to obtain a better integrated pH sensing property. Furthermore, a potential compensation method with a specially designed probe structure was proposed to correct possible errors caused by the potential drift of IrO x pH electrode in long-term pH monitoring. pH, used to reflect the grade of solvents in chemical laboratory since 1909, is an important parameter in many fields such as chemical industry, bio-industry as well as some fundamental research like electrodeposition/electrolysis and corrosion process.1-3 The glass pH electrode is a mature routine tool presenting good sensitivity, excellent stability and long life time in pH sensing. However, some of its disadvantages restrict its usage in some particular applications due to the physical nature of the glass membrane.The alternative pH electrodes include ion-sensitive field-effect transistor (ISFET) pH sensors, 4,5 optical fiber pH sensors, 6,7 hydrogel film pH sensors, [8][9][10][11][12] metal/metal oxide sensors, 13-16 etc. By comparing sensitivity, Nernst response range, ion selectivity, interference of oxidation, the iridium oxide pH electrode has been demonstrated to be the most promising one among all kinds of pH sensors. [17][18][19] The reported fabrication approaches of IrO x pH electrode include electrochemical cyclic voltammetry (CV), 19-22 electrodeposition, 23-25 radio frequency (RF) magnetron sputtering deposition, 26-30 and thermal oxidation.14,31 Among which, the electrode produced by thermal oxidation exhibited excellent overall performance, including wide E-pH relationship range, fast response time and long term stability.32-36 Wang et al. developed carbonate melt oxidation to coat Ir through the oxidation of Ir wires in a carbonate melt at 870• C for 5 hours.31 Hitchman et al. produced IrO x -electrodes by direct thermal oxidation in air at 800• C. 34 Both surface films of fabricated by the above conditions showed obvious cracks...

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Section: Resultsmentioning

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The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

Huang¹,

Wan²,

Jin³

et al. 2017

J. Electrochem. Soc.

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“…Besides, the produced IrO x electrode shows excellent comprehensive properties including wide E-pH range, near Nernst pH sensitivity, fast response rate, and good long term stability etc., 22,33 which makes the current pH detection available, the details of above properties will not be repeated here.…”

Section: Resultsmentioning

confidence: 99%

Application of Cyclic Thermal-Oxidized IrOx Electrode in pH Detection of Zn/Steel Galvanic Process in 3.5 wt.% NaCl Solution

Huang

et al. 2020

J. Electrochem. Soc.

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The IrOx electrodes fabricated by cyclic heating and quenching process show excellent comprehensive properties including wide E-pH range, near Nernst pH sensitivity, fast response rate, and long term stability etc. The IrOx electrodes are applied in the detection of surface pH changes during galvanic corrosion process of zinc/steel couple in 1 mm 3.5 wt.% NaCl electrolyte layer and 3.5 wt.% NaCl bulk solution, respectively. This detection is realized by integrating the self-fabricated IrOx pH sensor and self-assembled moving platform together. Before the application of the IrOx electrode, the appropriate way of scanning the surface of the zinc/steel galvanic couple is discussed. Comparing with the case in bulk solution, the zinc/steel couple corrodes faster in 1 mm electrolyte layer, the surface pH of which increases to a high value after corrosion begins for 20∼40 min, and the low pH region exists on the zinc surface and the region adjacent to border area of the steel surface, whereas the pH value of the steel surface away from the border area is relatively high. It is demonstrated that the IrOx electrode could detect the pH distribution effectively in surface region during metal corrosion, which could help the understanding of corrosion process under different situations.

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“…As stipulated by the International Union of Pure and Applied Chemistry (IUPAC), when the rate of change of the electrode potential decreases to less than 1 mV/min, the electrode can be regarded as achieving a steady state. (37) Therefore, to meet this criterion, the response time of the electrode is defined by the time period needed for the stabilization of the electrode potential.…”

Section: Response Rate Of the Fabricated Iro X Electrodesmentioning

confidence: 99%

Insight into the Factors of Thermal Oxidation Influencing Properties of Iridium Oxide Electrodes

Huang¹,

Bi²,

Wan³

et al. 2020

Sensors and Materials

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Using thermal oxidation for fabricating iridium oxide (IrO x) electrodes is a good choice for obtaining robust pH electrodes. We fabricated IrO x electrodes at different temperatures for different heating times to obtain electrodes with different E (electrode potential)-pH responses, response rates, and long-term stability. Corresponding characterizations, which include surface morphology, section morphology and composition, surface composition, and surface roughness, are examined intensively. Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) are used to carry out the characterizations. All prepared electrodes had a near-Nernstian response, especially when heated at 750, 800, and 870 ℃ for 1.0 and 1.5 h. IrO x electrodes fabricated with these heat treatment parameters had a relatively high response speed, a small potential drift, few cracks on the surface oxide film, thick films, and a small reaction impedance. The surface roughness and composition of the IrO x electrodes fabricated at different temperatures for 1.5 h were also obtained to clarify the relationship between the electrode composition, structure, and properties. Finally, the properties of the electrodes and their relationship with technical preparation parameters and the electrode structure and composition are discussed.

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The Influences of Quenching Times on the Property of Thermal Oxidized Iridium pH Sensor

Cited by 3 publications

References 12 publications

The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

Application of Cyclic Thermal-Oxidized IrOx Electrode in pH Detection of Zn/Steel Galvanic Process in 3.5 wt.% NaCl Solution

Insight into the Factors of Thermal Oxidation Influencing Properties of Iridium Oxide Electrodes

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The Influences of Quenching Times on the Property of Thermal Oxidized Iridium pH Sensor

Cited by 3 publications

References 12 publications

The Effects of Cyclic Isothermal Oxidation on Ir/IrOxpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

The Effects of Cyclic Isothermal Oxidation on Ir/IrOxpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

Application of Cyclic Thermal-Oxidized IrOx Electrode in pH Detection of Zn/Steel Galvanic Process in 3.5 wt.% NaCl Solution

Insight into the Factors of Thermal Oxidation Influencing Properties of Iridium Oxide Electrodes

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The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode

The Effects of Cyclic Isothermal Oxidation on Ir/IrO_xpH Electrode and a Method to Correct the Potential Drift of Metal Oxide Electrode