Equivalent‐Circuit Elements and Modeling of the Impedance Phenomenon

Lvovich, Vadim F.

doi:10.1002/9781118164075.ch3

Cited by 9 publications

(2 citation statements)

References 10 publications

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“…Furthermore, we calculate an increasing pseudo capacitance (C2), from the fitted Q2 constant phase element during degradation. This can be caused by several factors, such as inhomogeneity of the surface, variability in conductivity, grain boundaries, and crystal phases of polycrystalline electrode, which contribute to the distributed time constants of the constant phase element representation. − Overall, diffusive resistance is introduced and OER kinetics are impeded during degradation, correlating to an increase in the electrically insulating nature of the electrode.…”

Section: Resultsmentioning

confidence: 99%

Degradation Mechanism of Calcium Iridium Oxide for Oxygen Evolution Reaction in Acid

Li,

Edgington,

Seitz

2023

Energy Fuels

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The development of active and acid-stable iridium-based catalysts is crucial to meet the requirements of proton exchange membrane technologies for the sustainable production of hydrogen via water electrolysis. However, long-term stability remains a critical challenge. In this work, we focus on a Ca 2 IrO 4 catalyst to develop a holistic picture of catalyst electronic and geometric structure evolution under various applied potentials by probing electrochemically active surface area, metal dissolution, Ir valence, and surface morphology. We observe an initial activity increase in parallel with increasing capacitance and minor iridium dissolution. Extensive chronoamperometry tests at oxidizing potentials lead to significant activity loss that occurs simultaneously with a dramatic drop in capacitance and a change in impedance. Using a combination of electrochemical and spectroscopic tools, we provide fundamental insights to these material degradation processes to enable future catalyst design with balanced activity and long-term stability.

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Section: Resultsmentioning

confidence: 99%

Degradation Mechanism of Calcium Iridium Oxide for Oxygen Evolution Reaction in Acid

Li,

Edgington,

Seitz

2023

Energy Fuels

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“…Additionally, the model includes two Constant Phase Elements (CPE) corresponding to the average capacitance of the medium (C Medium ) and the membrane of all cells (C Membrane ). These two capacitors are no ideal elements and thus it is required to use a positive fractional exponent less than the unity for each of them, "m" for the capacitor of the medium and "n" for the capacitor of the membrane; as a result, the impedance of a constant phase element can be described as the well-know general definition of it 35 : Z(ω) CPE ≡ 1 ⁄ (jω) m C; Here, "ω" is the frequency and j ≡ −( ) 1 is the imaginary number. By apply the substitution of the mathematical definition of the two CPEs in Fig.…”

Section: Discussionmentioning

confidence: 99%

Fabrication of an Active PCB-MEMS Microfluidic Chip for CHO Cells Characterization by Electrochemical Impedance Spectroscopy

Peña

Contreras-Saenz

Camacho-León

et al. 2021

J. Electrochem. Soc.

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This paper reports the use of laser ablation for the fabrication of a microfluidic device with integrated electrodes on a printed circuit board (PCB-MEMS). The fabricated novel device has flame retardant (FR)−4 resin as substrate, copper (Cu) as active material, and SU-8 polymer as a structural material. The resolution, repeatability, and simplicity achieved in this approach, along with the low cost of the involved materials and methods, enable an affordable micromachining technique with a rapid fabrication-test cycle to develop active microfluidic systems on a chip. Furthermore, an Electrochemical Impedance Spectroscopy (EIS) analysis was performed at different Chinese Hamster Ovary (CHO) cell concentrations (105 to 108 cfu ml−1) to validate device assembly and functionality. The electrical properties of the system were characterized and discussed through a proposed equivalent circuit model comprising five passive elements. The model describes ohmic and non-ideal capacitive behavior of the cytoplasm and membrane of the CHO cells as well as the suspending medium and electrical connections of the device. Likewise, two characteristic times associated with relaxation processes caused by a change in the path of charge transport through the cells are determined.

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One-pot synthesis of inorganic/organic hybrid membranes from organoalkoxysilane, hydroimidazole derivative, and cyclic sulfonic acid ester

et al. 2015

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Equivalent‐Circuit Elements and Modeling of the Impedance Phenomenon

Cited by 9 publications

References 10 publications

Degradation Mechanism of Calcium Iridium Oxide for Oxygen Evolution Reaction in Acid

Degradation Mechanism of Calcium Iridium Oxide for Oxygen Evolution Reaction in Acid

Fabrication of an Active PCB-MEMS Microfluidic Chip for CHO Cells Characterization by Electrochemical Impedance Spectroscopy

One-pot synthesis of inorganic/organic hybrid membranes from organoalkoxysilane, hydroimidazole derivative, and cyclic sulfonic acid ester

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