EIS and relaxation times study for CO adsorbed on bimetallic Pt-Mo catalysts during the methanol oxidation reaction

Reyes, Orlando Ugalde; Liu, H.; Roquero, Pedro; Álvarez‐Ramírez, José; Sosa-Hernández, E.

doi:10.1016/j.electacta.2022.140309

Cited by 13 publications

(8 citation statements)

References 22 publications

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“…The finite Warburg diffusional element has the impedance Z w given by the following [ 34 ]:

where: w is the frequency (Hz), j is the imaginary unit, τ D is a time constant associated with the mass transfer and R D is the resistance of the finite Warburg diffusional element. The existence of the Warburg resistance is related to the corrosion process controlled by the diffusion circulation.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Evaluation of Protective Coatings with Ti Additions on Mild Steel Substrate with Potential Application for PEM Fuel Cells

et al. 2022

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In this work, the corrosion behavior of NiCr(Ti) protective coatings deposited on mild steel substrates through laser cladding technology is studied as an alternative new material for metallic bipolar plates used in PEMFC applications. For electrochemical testing, a solution consisting of 0.5 M H2SO4 + 2 ppm F− at room temperature is used as an electrolyte. The fluoride ions are added to simulate the conditions in the PEM fuel cell due to degradation of the proton exchange membrane and fluoride release. A saturated calomel electrode (SCE) is used as a reference electrode and a platinum mesh as the counter electrode. Scanning electron microscopy (SEM) and optical microscopy (OM) are used for studying the morphology of the protective coatings and the effect of Ti addition. The electrochemical evaluation consisted of measuring the open circuit potential (OCP), followed by electrochemical impedance spectroscopy measurements (EIS) and potentiodynamic polarization. It is found that the coatings with 5% Ti, 7% Ti and 10% Ti addition comply with the conditions of the US DOE regarding corrosion performance to be used as materials for the manufacture of the bipolar plates.

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“…The finite Warburg diffusional element has the impedance Z w given by the following [ 34 ]:

Section: Resultsmentioning

confidence: 99%

Electrochemical Evaluation of Protective Coatings with Ti Additions on Mild Steel Substrate with Potential Application for PEM Fuel Cells

et al. 2022

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“…Following the aforesaid scenario, it becomes difficult to extract exact values of low-frequency resistance and capacitance and correlate them with a physical phenomenon in the material . To tackle this issue, distribution of relaxation times (DRT) is a useful technique for the deconvolution of EIS Nyquist spectra . DRT is a method to convert the frequency response obtained in EIS to the time domain, yielding the corresponding time constants of each physical process .…”

Section: Introductionmentioning

confidence: 99%

“…14 To tackle this issue, distribution of relaxation times (DRT) is a useful technique for the deconvolution of EIS Nyquist spectra. 15 DRT is a method to convert the frequency response obtained in EIS to the time domain, yielding the corresponding time constants of each physical process. 16 The technique is much leveraged for batteries and fuel cells to derive information about the change in dynamics after each charge−discharge cycle.…”

Section: Introductionmentioning

confidence: 99%

Deconvoluting the Impedance Response of Halide Perovskite Single Crystals: The Distribution of Relaxation Time Method

et al. 2023

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Electrochemical impedance spectroscopy (EIS) has been emerging as a promising tool to study the core mechanisms occurring within metal halide perovskites (MHPs). Generally, MHPs show one or two semicircles in the Nyquist spectra in the probed frequency range. However, in the presence of external stimuli, often a Warburg diffusion or an inductive loop is observed at low frequencies. In such cases, a comparison of low-frequency parameters in both cases cannot be drawn because of the lack of a unique electrical circuit (EC). To overcome the issue of lack of EC, transformation of the frequency-domain technique to the time domain is carried out. In this work, we investigated three different cases of MAPbI3, MAPbBr3, and surface-passivated MAPbBr3 single crystals (SCs), which showed one suppressed semicircle, two semicircles, and a Warburg-like diffusion, respectively, in the Nyquist response of EIS. Next, we transformed these spectra into the time domain using the distribution of relaxation times (DRT) technique, a machine-learning-assisted tool. The obtained results suggest that in the case of Nyquist spectra with one semicircle (the case of MAPbI3 SCs), the observed time constants using EC and DRT are close enough. However, in the case of MAPbBr3 SC, three different time constants are obtained, associated with high, medium, and low frequencies, although the Nyquist response showed two semicircles. At last, in the presence of surface-passivated SCs, the Warburg-like feature changes significantly for different passivation times. Interestingly, the DRT spectra showed almost similar time constants, through which reliable information on the low-frequency RC can be extracted. Thus, DRT can pave the way for the easy and reliable interpretation of EIS spectra, which is not possible using EC.

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“…Therefore, the introduction of transition metals into Pt-based catalysts can promote MOR activity through oxidative removal of the adsorbed CO and the release of active sites, according to eqn (2). [8][9][10][11] So far, most of the Ptbased catalyst design involves (i) alloying Pt with non-noble metals, and (ii) anchoring Pt catalysts onto transition-metal oxide supports. By comparison, anchoring Pt catalysts on various transition-metal oxide supports can significantly enhance electrocatalytic activity and stability.…”

Section: Introductionmentioning

confidence: 99%

A high-performance Pt-based catalyst for the methanol oxidation reaction: effect of electrodeposition mode and cocatalyst on electrocatalytic activity

et al. 2023

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EIS and relaxation times study for CO adsorbed on bimetallic Pt-Mo catalysts during the methanol oxidation reaction

Cited by 13 publications

References 22 publications

Electrochemical Evaluation of Protective Coatings with Ti Additions on Mild Steel Substrate with Potential Application for PEM Fuel Cells

Electrochemical Evaluation of Protective Coatings with Ti Additions on Mild Steel Substrate with Potential Application for PEM Fuel Cells

Deconvoluting the Impedance Response of Halide Perovskite Single Crystals: The Distribution of Relaxation Time Method

A high-performance Pt-based catalyst for the methanol oxidation reaction: effect of electrodeposition mode and cocatalyst on electrocatalytic activity

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