Kinetics of Hydrogen Oxidation Reaction on Pt Catalysts Used in Fuel Cells
Date Issued
2005
Date
2005
Author(s)
Lin, Ren-Bin
DOI
en-US
Abstract
The hydrogen oxidation reaction on the Pt-black/Nafion and Nafion-coated Pt/C electrodes were investigated using the rotating disk electrode (RDE) and cyclic voltammetry (CV) techniques. The voltammetric results demonstrated that the thin-film electrodes can be prepared with a good reproducibility. The coating of Nafion film (≦8 μm) had a negligible effect on the electrochemical surface area of an electrode, and the electrochemical and real Pt surface areas of an electrode were equal. The current density for the H2 oxidation reaction decreased as the Nafion film thickness increased. However, the diffusional resistance for H2 in the Nafion film was negligible when the film thickness was smaller than 0.2 μm. The hydrodynamic voltammograms were analyzed to determine the kinetic parameters using the modified Koutecky-Levich equation. The H2 permeability in the recast Nafion film was in the range of 2.0×10-5 to 5.2×10-5 mM cm2s-1. The effect of H2 diffusion in the catalyst layer on the reaction rate was accounted for using the effectiveness factor. The corrected exchange current densities for the Pt-black and Pt/C catalysts were determined to be about 0.49 and 0.96 mA cm-2, based on the real Pt surface area, respectively.
The thin-film RDE method has been demonstrated to be efficient and accurate for characterizing the electrochemical surface area of the catalyst, evaluating the performance of the polymer electrolyte, and determining the kinetic parameters under fuel cell relevant conditions. The results of this study are useful for designing the electrodes for fuel cells using Pt-black and Pt/C catalysts.
Subjects
電催化
旋轉電極
氫氣氧化
白金
燃料電池
Electrocatalysis
Rotating disk electrode
Hydrogen oxidation
Platinum
Polymer electrolyte
Fuel cell
Type
thesis