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Technology Reviews

Review on the Properties of Nano-/Microstructures in the Catalyst Layer of PEMFC

[+] Author and Article Information
Xiao Yu, Bengt Sundén

Department of Energy Sciences, Faculty of Engineering, Lund University, 22100 Lund, Sweden

Jinliang Yuan1

Department of Energy Sciences, Faculty of Engineering, Lund University, 22100 Lund, Swedenjinliang.yuan@energy.lth.se

1

Corresponding author.

J. Fuel Cell Sci. Technol 8(3), 034001 (Mar 01, 2011) (13 pages) doi:10.1115/1.4003170 History: Received October 13, 2010; Revised November 05, 2010; Published March 01, 2011; Online March 01, 2011

Abstract

The catalyst layer (CL) of a proton exchange membrane fuel cell involves various particles and pores that span a wide range of length scales, from several nanometers to a few microns. The success of the CL design depends decisively on understanding the detailed structure in microscale or even in nanoscale. In this paper, the properties of nano-/microstructures are outlined, and the physical and chemical processes are analyzed on the Pt surfaces. A software package of automatic simulation environment is developed and applied to investigate the electronic structure of the Pt–H system. Then, the $H2$ dissociative adsorption process is obtained using the nudged elastic band approach. The modeling of the nanocomposites in the CLs is a multiscale problem. The nanoscale models are used for investigating the structural evolution and the interactions between Pt/C particles and polymer components; while the microscale simulations, which aim to bridge molecular methods and continuum methods, are extended to describe the morphology of heterogeneous materials and rationalize their effective properties beyond length- and time-scale limitations of the atomistic simulations. However, there are still some major challenges and limitations in these modeling and simulations. The multiscale modeling should be developed to demonstrate the usefulness for engineering design with the longstanding goal of predicting particle-structure-property.

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Figures

Figure 1

Schematic illustration of a cathode catalyst layer (1). Reprinted from Ref. 1 with permission from Elsevier.

Figure 2

TEM images of the catalyst with different substrates: (a) Pt50/VC-X and (b) Pt33/KB(20). Reprinted from Ref. 20 with permission from Elsevier.

Figure 3

TEM images of (a) ordered mesoporous carbon (21), (b) CNFs (22), and (c) CNTs (23). Reprinted from Refs. 21-23 with permission from Elsevier.

Figure 4

((a) and (c)) TEM images and ((b) and (d)) enlarged HR-TEM images of the Pt/C catalyst prepared with 10×CMC and 50×CMC of B+T, respectively (25). Reprinted from Ref. 25 with permission from Elsevier.

Figure 5

(a) The HR-TEM image and (b) the particle size distribution of the 3Pt1Sn/C catalyst (27). Reprinted from Ref. 27 with permission from Elsevier.

Figure 6

HR-TEM image of (a) 20Pt–10CeO2/C catalysts and (b) EDX pattern for the 20Pt–10CeO2/C catalyst (29). Reprinted from Ref. 29 with permission from Elsevier.

Figure 7

Typical HR-TEM image of the MWCNT/PyPBI/Pt. The Pt nanoparticles are penetrated into the thin PyPBI-coating layer to contact closely with the MWCNT surfaces (30). Reprinted from Ref. 30 with permission from Elsevier.

Figure 8

Representations of the H2–Pt(111) systems. The interatomic distance r, the H2 CM distance Z from the surface, the polar angle θ, and the azimuthal angle Φ are illustrated in (a). The H2–Pt configurations are also shown for the adsorption of H2 on the ideal surface (b) and on the defective surface with vacancies at sites (c) 1, (d) 2, (e) 3, and (f) 4. The surface unit cell is given in (b), with a lattice constant of 2.772 Å (36). Reprinted from Ref. 36 with permission from Elsevier.

Figure 9

The MEP for H atom diffusion on Pt(111) surface and the images under the equilibrium states (the red dots)

Figure 10

MEP for H2 dissociative adsorption on the Pt(111) surface

Figure 11

Oxygen reduction reaction pathways

Figure 12

Details of the interface catalyst surface/water/Nafion (for a polymer content of 7 Nafion-4/cell, λ=24) (70). Reprinted from Ref. 70 with permission from Elsevier.

Figure 13

A conceptual representation of the implementation of SOFC porous structures into a LBM model. (a) A representation of the pore structure where the white regions are the pore and the black regions represent the dense Ni and YSZ materials. (b) A binary representation of this structure, as read by the LBM, where “1” is a pore and “0” is a dense region. (c) Discrete electrochemical boundary conditions are implemented with a unique binary indicator, “2,” at the interface. False colors are used as a visual guide (99). Reprinted from Ref. 99 with permission from Elsevier.

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