Temperature Effects on PEM Fuel Cells Pt/C Catalyst Degradation

Bi, Wu; Fuller, Thomas F.

doi:10.1149/1.2781037

Cited by 35 publications

(14 citation statements)

References 14 publications

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“…The results show that increasing operating temperature leads to improvement in cell performance, due to increase membrane conductivity and gas diffusivity with higher operating temperature that result in better mass transport and thus better limiting current densities. This trend is consistent with the experimental work of [65], [66]. Wang et al [65] concluded that the performance of the PEM fuel cell improves with the increase of operating temperature, if sufficient humidification is ensured.…”

Section: Effect Of Operating Temperaturesupporting

confidence: 88%

Proton exchange membrane (PEM) fuel cell parametric study via mathematical modeling and numerical simulation

Jaralla¹

2023

Preprint

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In the proton exchange membrane (PEM) fuel cell study, numerical analysis of complex and coupled multi-disciplinary processes involving the subjects of fluid dynamics, heat transfer, mass transport, and electrochemistry has been attempted over the past few decades. However, many resulting models are, in spite of fancier functionalities such as three-dimensionality, too complex to implement on account of the digital hardware requirement as well as computation time consumption. On the other hand, three-dimensional analytical models reported in literature look much simple, but they are embedded by a number of fairly unrealistic assumptions and, hence, lead to significantly weakened usability. In this thesis, a set of detailed two-dimensional non-isothermal computational models for PEM fuel cells in x-y and y-z planes are developed, which aims at the equivalency with the 3D PEM fuel cell model and, moreover, gains more insights with significantly reduced computational cost. The complete model consisting of the equations of continuity, momentum, energy, species concentrations, and electric potentials in different regions of a PEM fuel cell are numerically solved using the finite element method implemented into a commercial CFD (COMSOL) code. A comprehensive comparison with the experimental data has been performed to validate the 2D models developed in this study. On the basis of simulations of various flow and transport phenomena in an operational PEMFC, a systematic parametric study is conducted using the present developed PEM fuel cell models. A number of operating and design parameters are examined, including the operating pressure, ambient temperature, relative humidity, the porosity of the gas diffusion layer (GDL), the effective porosity of catalyst layer (CL), the porosity of membrane (M), the proton conductivity and the air inlet velocity at cathode side. The obtained results of this study revelaed that the membrane porosity, and air inlet velocity have considerable effects on the water content in the membrane, thus it is essential to select the proper values of these parameters to improve water management in the cell and avoid dehydration the membrane or flooding the electrode. Also, it is found that increasing air velocity at the inlet of the cathode gas channel has a significant effect on the temperature distribution in PEM fuel cell, as the temperature a noticeably dropped with higher inlet air velocity. The numerically results also found that with higher porosities of gas diffusion layers (GDLs) and catalyst layers (CLs), the performance of PEM fuel cell improved. In addition, it found that a higher performance can be achieved when fuel cell operated with reasonably higher operating temperature, operating pressure, proton conductivity and ensuring a full hydration of the reactants. The outcome of this study demonstrates that the present developed PEM fuel cell models can serve as a useful tool for understanding of transport and electrochemical phenomena in PEM fuel cell as well as for optimization of cell design and operating conditions.

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Section: Effect Of Operating Temperaturesupporting

confidence: 88%

Proton exchange membrane (PEM) fuel cell parametric study via mathematical modeling and numerical simulation

Jaralla¹

2023

Preprint

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“…Rare but highly important previous studies focused mainly on the effects of temperature on the kinetics of carbon support corrosion demonstrated that higher rates of carbon oxidation are expected with increasing operating temperature of the PEMFC. 31 − 33 However, there also exists a limited number of past studies that address the relation of Pt dissolution and temperature both on Pt NPs 34 − 38 as well as bulk Pt. 39 − 41 In addition to these studies, Cherevko and co-workers 42 followed with the first study on the temperature-dependent dissolution of polycrystalline Pt by coupling of the scanning flow cell (SFC) with an inductively coupled plasma mass spectrometer (ICP-MS).…”

Section: Introductionmentioning

confidence: 99%

Understanding the Crucial Significance of the Temperature and Potential Window on the Stability of Carbon Supported Pt-Alloy Nanoparticles as Oxygen Reduction Reaction Electrocatalysts

et al. 2021

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The present research provides a study of carbon-supported intermetallic Pt-alloy electrocatalysts and assesses their stability against metal dissolution in relation to the operating temperature and the potential window using two advanced electrochemical methodologies: (i) the in-house designed high-temperature disk electrode (HT-DE) methodology as well as (ii) a modification of the electrochemical flow cell coupled to an inductively coupled plasma mass spectrometer (EFC-ICP-MS) methodology, allowing for highly sensitive time- and potential-resolved measurements of metal dissolution. While the rate of carbon corrosion follows the Arrhenius law and increases exponentially with temperature, the findings of the present study contradict the generally accepted hypothesis that the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature. On the contrary, clear evidence is presented that in addition to the importance of the voltage/potential window, the temperature is one of the most critical parameters governing the stability of Pt and thus, in the case of Pt-alloy electrocatalysts, also the ability of the nanoparticles (NPs) to retain the less noble metal. Lastly, but also very importantly, results indicate that the rate of Pt redeposition significantly increases with temperature, which has been the main reason why mechanistic interpretation of the temperature-dependent kinetics related to the stability of Pt remained highly speculative until now.

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“…Indeed, it is known that catalysts can be either reduced or oxidized during the catalytic process. , Even though some reactions such as ORR and HER are performed at room temperature (RT), the sample was studied at elevated temperature to accelerate and amplify the effects of exposure to O 2 and H 2 . Hence, the experiment provides an insight into degradation mechanisms occurring after long usage of the nanocatalysts . Additionally, an in situ study of the sample under H 2 at elevated temperature describes structural changes during annealing, a crucial step often performed after synthesis to improve the random distribution of Co and Pt. ,, …”

Section: Resultsmentioning

confidence: 99%

Structural and Valence State Modification of Cobalt in CoPt Nanocatalysts in Redox Conditions

et al. 2021

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Platinum is the primary catalyst for many chemical reactions in the field of heterogeneous catalysis. However, platinum is both expensive and rare. Therefore, it is advantageous to combine Pt with another metal to reduce cost while also enhancing stability. To that end, Pt is often combined with Co to form Co–Pt nanocrystals. However, dynamical restructuring effects that occur during reaction in Co–Pt ensembles can impact catalytic properties. In this study, model Co2Pt3 nanoparticles supported on carbon were characterized during a redox cycle with two in situ approaches, namely, X-ray absorption spectroscopy (XAS) and scanning transmission electron microscopy (STEM) using a multimodal microreactor. The sample was exposed to temperatures up to 500 °C under H2, and then to O2 at 300 °C. Irreversible segregation of Co in the Co2Pt3 particles was seen during redox cycling, and substantial changes of the oxidation state of Co were observed. After H2 treatment, a fraction of Co could not be fully reduced and incorporated into a mixed Co–Pt phase. Reoxidation of the sample increased Co segregation, and the segregated material had a different valence state than in the fresh, oxidized sample. This in situ study describes dynamical restructuring effects in CoPt nanocatalysts at the atomic scale that are crucial to understand in order to improve the design of catalysts used in major chemical processes.

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Temperature Effects on PEM Fuel Cells Pt/C Catalyst Degradation

Cited by 35 publications

References 14 publications

Proton exchange membrane (PEM) fuel cell parametric study via mathematical modeling and numerical simulation

Proton exchange membrane (PEM) fuel cell parametric study via mathematical modeling and numerical simulation

Understanding the Crucial Significance of the Temperature and Potential Window on the Stability of Carbon Supported Pt-Alloy Nanoparticles as Oxygen Reduction Reaction Electrocatalysts

Structural and Valence State Modification of Cobalt in CoPt Nanocatalysts in Redox Conditions

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