The Interfacial Charging Transient of Gas Sensors Made from Porous Gas-Diffusion Electrodes

Lu, Juntao; Gong, Siling; Yan, Hao; Yang, Jing

doi:10.1002/(sici)1521-4109(199904)11:4<249::aid-elan249>3.0.co;2-8

Cited by 1 publication

(3 citation statements)

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“…Previous workers have considered possible electrical limitations on the measured gas sensor response times [18,30] . In a potentiostatic experiment, these effects can arise because the applied potential is divided between the working electrode/solution interface, the reference electrode/solution interface and the solution resistance.…”

Section: Resultsmentioning

confidence: 99%

“…Eqs. ( 9), ( 29) and (30) show that slow interfacial kinetics does not affect the shape of the long-time (small s) region of the data because the ratio � j= � J is independent of s as s ! 0.…”

Section: Interfacial Kineticsmentioning

confidence: 97%

“…Previous workers have considered possible electrical limitations on the measured gas sensor response times. [18,30] In a potentiostatic experiment, these effects can arise because the applied potential is divided between the working electrode/ solution interface, the reference electrode/solution interface and the solution resistance. There are three generic possibilities: either (i) the ohmic drop in the solution varies when a current flows in the presence of analyte, (ii) the presence of the analyte causes a small change in the interfacial capacitance of the working electrode, or (iii) a shift in the reference potential generates a charging current despite the diffusion-limited nature of the sensing reaction.…”

Section: Chronoamperometric Response To a Concentration-stepmentioning

confidence: 99%

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Diffusion Models of Mass Transport for the Characterisation of Amperometric Gas Sensors

Saunders,

Mudashiru,

Baron

et al. 2024

ChemElectroChem

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A diffusion model for the analysis of chronoamperometric data in response to a concentration step is developed for amperometric gas sensors. This analysis avoids the difficulties with standard potentiodynamic measurements at the large specific area, high capacitance electrodes employed in these sensors. Despite the fact that typical devices comprise multiple layers with varying thicknesses and diffusivities, we show that typical chronoamperometric traces can be fitted to a simple diffusion model with a single parameter where L is an overall effective thickness of the diffusion barrier and D is an effective diffusion coefficient. Through a comparison of the transient and steady‐state current, independent estimates of L and D in the devices can be made. The model is also extended to cover cases with interfacial kinetic barriers; such kinetic limitations lead to a change in the effective values L and D, but the simple diffusion model remains a good fit to the data. This analysis shows that transient sensor responses can be characterised by a single parameter τ and conversely that deviations from this regression model cannot be assigned to (i) complex layer architectures or (ii) interlayer kinetic barriers. Instead, we show that non‐uniform accessibility effects arising from a distribution of diffusion rates across the device lead to deviations from the simple regression model, but that they may be captured approximately by a more complex model in which τ has a probability distribution.

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Section: Resultsmentioning

confidence: 99%

Section: Interfacial Kineticsmentioning

confidence: 97%

Section: Chronoamperometric Response To a Concentration-stepmentioning

confidence: 99%

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