Solid electrolyte gas sensors based on mixed potential principle – A review

Ritter, Thomas; Zösel, J.; Guth, U.

doi:10.1016/j.snb.2023.133508

Cited by 10 publications

(9 citation statements)

References 132 publications

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“…We suspected a sensitivity of uncoated Ti electrodes to pH as electrodes made from other metals with a surface oxide layer, such as antimony, iridium, or palladium, are well-known to exhibit potentiometric responses to pH. , Indeed, pH sensitivity was observed for clean, sanded Ti rods when they were immersed into 1.0 M KCl solution, and the pH was varied between pH 2 and 12 by addition KOH or HCl (see Figure S4). As expected, the Ti rods showed a change in potential of −36.7 ± 1.7 mV per pH unit.…”

Section: Resultsmentioning

confidence: 99%

Microporous Ag/AgCl on a Titanium Scaffold for Use in Capillary Reference Electrodes

Robinson,

Troudt,

Bühlmann

2024

Anal. Chem.

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AgCl-coated silver fabricated with the thermalelectrolytic method can be used to prepare more reproducible reference electrodes than Ag/AgCl prepared with alternative methods such as electrolytic and chemical AgCl deposition or thermal fabrication. However, thermal-electrolytic fabrication requires a scaffold material upon which to build the layers upon. Platinum and rhodium have been used for this purpose as they are mechanically strong and chemically inert, but their cost is prohibitive for wider application. Herein, we report the stability of Ag/AgCl reference electrodes built atop a titanium scaffold using the thermal-electrolytic method and the use of these Ti/Ag/ AgCl constructs in capillary-based reference electrodes. Electrochemical characterization shows that the probable presence of small amounts of oxygen at the Ti/Ag interface does not affect the reference electrode performance; in particular, over a wide pH range, the half-cell potential is pH independent. The electrical resistance of the Ti/Ag/AgCl/KCl system is dominated by the charge transfer resistance at the interface of the AgCl to KCl solution but is kept very small by the large AgCl surface area and a high solution concentration of chloride. The resulting high exchange current minimizes the effect of system impurities on the reference half-cell potential. Capillary-based reference electrodes comprising Ti/Ag/AgCl show exceptionally low potential drifts (as low as 0.03 ± 2.01 μV/h) and standard deviations of the potential at or below ±0.5 mV over a 60 h period. These capillary-based reference electrodes are suitable for very small sample volumes while still providing a free-flowing liquid junction that prevents reference electrode contamination.

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Section: Resultsmentioning

confidence: 99%

Microporous Ag/AgCl on a Titanium Scaffold for Use in Capillary Reference Electrodes

Robinson,

Troudt,

Bühlmann

2024

Anal. Chem.

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“…As mentioned earlier, the sensor is operated in its electrolysis galvanostatic mode, i.e., a constant current I is applied between WE and CE and a potential difference

is measured between WE and RE:

( Figure 2 ). The measured voltage is given by the following equation [ 26 ]:

where

is the output voltage measured between WE and RE when no current is applied between the electrodes (

is considered null at I = 0),

is the cathodic overpotential, and R is the electrolyte resistance. The overpotential is linked to an additional quantity of energy required (compared to the one expected thermodynamically) by a reaction to occur over an electrode.…”

Section: Methodsmentioning

confidence: 99%

“…The overpotential is linked to an additional As mentioned earlier, the sensor is operated in its electrolysis galvanostatic mode, i.e., a constant current I is applied between WE and CE and a potential difference ∆V re f is measured between WE and RE: 2). The measured voltage is given by the following equation [26]:…”

Section: Sensor's Physical and Electrochemical Descriptionmentioning

confidence: 99%

“…Indeed, in tests carried out on electrochemical sensors, when several species can react at the same time on the same electrode, the thermodynamic equilibrium reached on each of the electrodes is different from the Nernst equilibrium. In this case, a more suitable model, presented in review articles by S. Haley et al [ 25 ] and T. Ritter et al [ 26 ], is the theory of mixed potentials. This theory has been used, for example, by X. Hao et al [ 27 ] to explain the response of the electrochemical sensor developed from a conventional YSZ electrolyte and a new type of measuring electrode: Nd 2 AO 4 (with A=Cu, Ba and Ni) to concentrations of H 2 S below 1 ppm.…”

Section: Introductionmentioning

confidence: 99%

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From the Modeling of an Electrochemical YSZ-Based Gas Sensor Used in Electrolysis Mode

Lakhmi,

Viricelle,

Alrammouz

et al. 2024

Sensors

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Electrochemical sensors have been used for many decades. However, the modeling of such sensors used in electrolysis mode is poorly documented, especially in the case of multiple gases’ parallel actions. These are of great interest since they constitute the first brick to bring information on the natures and concentrations of gaseous mixture compositions, thanks to gray box modeling of sensor arrays, for example. Based on Butler–Volmer’s equations, a model assuming parallel reactions at gold cathode has been introduced in this article and confronted with experimental results. The establishment of the model is based on the extraction of three variables: the charge transfer coefficient “α”, the reaction order γ, and the reaction constant rate k0. Tests performed without pollutants and with different concentrations of oxygen could be nicely fitted using the model. The influence of the polarization current on the three variables of the model has been evaluated, showing a clear influence on the constant rate and the reaction order. Moreover, increasing the polarization current enabled us to obtain selectivity for oxidant gases. Similarly, the effect of the oxygen concentration was evaluated. Results showed that, in this case, the charge transfer coefficients “α” obtained for oxidant gases are quite different from the ones obtained in the polarization current varying conditions. Therefore, the model will be interesting in situations where polarization current and oxygen content are not varied together. Variation of polarization current can be quite interesting to obtain increased information for multivariate analysis purposes in constant oxygen content situations. Additionally, other parameters have to be considered for applications in which the oxygen content is bound to change, such as exhaust gases or combustion.

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“…They are also denoted as non-equilibrium sensors. They are often based on yttria-stabilized zirconia (YSZ) as the oxygen-ion-conducting solid electrolyte [10][11][12][13][14][15][16]. In addition, various metal oxides are used directly as sensor electrodes [17][18][19][20][21] or on top of a noble metal electrode [22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Mixed-Potential Ammonia Sensor Based on a Dense Yttria-Stabilized Zirconia Film Manufactured at Room Temperature by Powder Aerosol Deposition

Donker,

Schönauer-Kamin,

Moos

2024

Sensors

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Powder aerosol deposition (often abbreviated as PAD, PADM, or ADM) is a coating method used to obtain dense ceramic films at room temperature. The suitability of this method to obtain ammonia mixed-potential sensors based on an yttria-stabilized zirconia (YSZ) electrolyte that is manufactured using PAD and a V2O5–WO3–TiO2 (VWT)-covered electrode is investigated in this study. The sensor characteristics are compared with data from sensors with screen-printed YSZ solid electrolytes. The PAD sensors outperform those in terms of sensitivity with 117 mV/decade NH3 compared to 88 mV/decade. A variation in the sensor temperature shows that the NH3 sensitivity strongly depends on the sensor temperature and decreases with higher sensor temperature. Above 560 °C, the characteristic curve shifts from exponential to linear dependency. Variations in the water and the oxygen content in the base gas (usually 10% oxygen, 2% water vapor in nitrogen) reveal a strong dependence of the characteristic curve on the oxygen content. Water vapor concentration variations barely affect the sensor signal.

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Solid electrolyte gas sensors based on mixed potential principle – A review

Cited by 10 publications

References 132 publications

Microporous Ag/AgCl on a Titanium Scaffold for Use in Capillary Reference Electrodes

Microporous Ag/AgCl on a Titanium Scaffold for Use in Capillary Reference Electrodes

From the Modeling of an Electrochemical YSZ-Based Gas Sensor Used in Electrolysis Mode

Mixed-Potential Ammonia Sensor Based on a Dense Yttria-Stabilized Zirconia Film Manufactured at Room Temperature by Powder Aerosol Deposition

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