Effect of Nafion content and hydration level on the electrochemical area of Pt nanocatalyst in the triple-phase boundary

2021 ◽  
Author(s):  
Juan Carlos Jimenez ◽  
Jimena A. Olmos-Asar ◽  
Esteban A. Francheschini ◽  
Marcelo Mario Mariscal
Keyword(s):  
Fuel Cells ◽  
Phase Boundary ◽  
Polymeric Membrane ◽  
Triple Phase Boundary ◽  
Hydration Level

Despite the great scientific effort, there are still some aspects of polymeric membrane-based fuel cells (PEMFC) operation that are difficult to access experimentally. This is the case of the so-called...

scholarly journals Role of Reaction Intermediate Diffusion on the Performance of Platinum Electrodes in Solid Acid Fuel Cells

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1065
Author(s):  
Oliver Lorenz ◽  
Alexander Kühne ◽  
Martin Rudolph ◽  
Wahyu Diyatmika ◽  
Andrea Prager ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Phase Boundary ◽  
Solid Acid ◽  
Diffusion Processes ◽  
Reaction Pathways ◽  
Reaction Intermediates ◽  
Boundary Area ◽  
Triple Phase Boundary ◽  
Boundary Length ◽  
Double Phase

Understanding the reaction pathways for the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR) is the key to design electrodes for solid acid fuel cells (SAFCs). In general, electrochemical reactions of a fuel cell are considered to occur at the triple-phase boundary where an electrocatalyst, electrolyte and gas phase are in contact. In this concept, diffusion processes of reaction intermediates from the catalyst to the electrolyte remain unconsidered. Here, we unravel the reaction pathways for open-structured Pt electrodes with various electrode thicknesses from 15 to 240 nm. These electrodes are characterized by a triple-phase boundary length and a thickness-depending double-phase boundary area. We reveal that the double-phase boundary is the active catalytic interface for the HOR. For Pt layers ≤ 60 nm, the HOR rate is rate-limited by the processes at the gas/catalyst and/or the catalyst/electrolyte interface while the hydrogen surface diffusion step is fast. For thicker layers (>60 nm), the diffusion of reaction intermediates on the surface of Pt becomes the limiting process. For the ORR, the predominant reaction pathway is via the triple-phase boundary. The double-phase boundary contributes additionally with a diffusion length of a few nanometers. Based on our results, we propose that the molecular reaction mechanism at the electrode interfaces based upon the triple-phase boundary concept may need to be extended to an effective area near the triple-phase boundary length to include all catalytically relevant diffusion processes of the reaction intermediates.

Use of layered double hydroxides to improve the triple phase boundary in anion-exchange membrane fuel cells

2010 ◽  
Vol 195 (19) ◽  
pp. 6500-6503 ◽  
Author(s):  
Kohei Miyazaki ◽  
Takeshi Abe ◽  
Koji Nishio ◽  
Haruyuki Nakanishi ◽  
Zempachi Ogumi
Keyword(s):  
Fuel Cells ◽  
Phase Boundary ◽  
Anion Exchange ◽  
Layered Double Hydroxides ◽  
Anion Exchange Membrane ◽  
Triple Phase Boundary ◽  
Double Hydroxides ◽  
Exchange Membrane

Triple phase boundary augmentation in hierarchical, Pt grafted N-doped mesoporous carbon nanofibers for high performance and durable PEM fuel cells

2018 ◽  
Vol 6 (26) ◽  
pp. 12768-12781 ◽  
Author(s):  
Karthikeyan K. Karuppanan ◽  
Appu V. Raghu ◽  
Manoj Kumar Panthalingal ◽  
Sivasubramanian Ramanathan ◽  
Thanarajan Kumaresan ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Phase Boundary ◽  
Carbon Nanofibers ◽  
Mesoporous Carbon ◽  
High Performance ◽  
Pem Fuel Cells ◽  
Triple Phase Boundary

Pt-grafted, hierarchical mesoporous carbon nanofibers (Pt/MPCNFs) electrocatalysts have been developed using electrospinning for high-performance PEM fuel cells.

Reaction Kinetics at the Triple-Phase Boundary in PEM Fuel Cells

2008 ◽  
Vol 5 (2) ◽  
Author(s):  
P. Berg ◽  
A. Novruzi ◽  
O. Volkov
Keyword(s):  
Fuel Cells ◽  
Phase Boundary ◽  
Reaction Kinetics ◽  
Surface Diffusion ◽  
Liquid Water ◽  
Numerical Technique ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Chemical Components ◽  
Triple Phase Boundary

A mathematical model is developed to describe the reaction dynamics in the vicinity of the triple-phase boundary (TPB), which is an important part of the pore scale structure of the catalyst layer in proton exchange membrane fuel cells. The model incorporates coupled diffusion, migration, and reaction phenomena of the chemical components in an undersaturated air pore and ionomer. One challenging feature of the work is the description of the TPB by a system of nonlinear partial differential equations (PDEs), coupling bulk, and surface-diffusion phenomena, which offers an approach to study the rarely investigated proton surface diffusion along the air pore surface. A numerical technique is implemented, taking into account the particular form of the domain, in order to solve the nonlinear PDE system efficiently. Several numerical results are discussed, including a sensitivity analysis with respect to the physical reference case and geometric parameters. The results indicate that surface diffusion might play a major role for the reaction kinetics, but only if the air pore is void of liquid water. In contrast, the formation of liquid water in the gas pores will turn surface diffusion into bulk diffusion, with the latter resembling the Grotthus mechanism.

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