skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.

Abstract

Recent progress in synthesizing and characterizing aligned carbon nanotubes (ACNT) as the electrode catalyst material for proton exchange membrane fuel cells (PEMFC) is reported. Catalytically functionalized ACNT active towards the electrocatalytic reduction of oxygen were prepared by a chemical vapor deposition method. The electrocatalytic activities and the nanostructures of the ACNT layers were investigated by cyclic voltammetry and scanning electron microscopy. To understand the nature of the transition metal as the catalytically active site in the ACNT, we also conducted an in situ X-ray absorption spectroscopic investigation at the Advanced Photon Source at Argonne National Laboratory. The oxidation state and coordination structure of the transition metals embedded inside the nanotubes were monitored by examining the EXAFS spectra collected under different polarization potentials. We clearly observed the change in the electronic and coordinational structures during the oxygen reduction reaction.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
EE; USDOE Office of Science (SC)
OSTI Identifier:
944526
Report Number(s):
ANL/CMT/JA-58308
TRN: US0900540
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: ECS Transactions; Journal Volume: 5; Journal Issue: 1 ; 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
30 DIRECT ENERGY CONVERSION; 36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; ABSORPTION; ADVANCED PHOTON SOURCE; CARBON; CATALYSTS; CHEMICAL VAPOR DEPOSITION; ELECTRODES; FUEL CELLS; NANOSTRUCTURES; NANOTUBES; OXYGEN; POLARIZATION; PROTON EXCHANGE MEMBRANE FUEL CELLS; SCANNING ELECTRON MICROSCOPY; SPECTRA; TRANSITION ELEMENTS; VALENCE

Citation Formats

Liu, D. J., Yang, J., and Gosztola, D. J. Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.. United States: N. p., 2007. Web. doi:10.1149/1.2728997.
Liu, D. J., Yang, J., & Gosztola, D. J. Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.. United States. doi:10.1149/1.2728997.
Liu, D. J., Yang, J., and Gosztola, D. J. Mon . "Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.". United States. doi:10.1149/1.2728997.
@article{osti_944526,
title = {Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.},
author = {Liu, D. J. and Yang, J. and Gosztola, D. J.},
abstractNote = {Recent progress in synthesizing and characterizing aligned carbon nanotubes (ACNT) as the electrode catalyst material for proton exchange membrane fuel cells (PEMFC) is reported. Catalytically functionalized ACNT active towards the electrocatalytic reduction of oxygen were prepared by a chemical vapor deposition method. The electrocatalytic activities and the nanostructures of the ACNT layers were investigated by cyclic voltammetry and scanning electron microscopy. To understand the nature of the transition metal as the catalytically active site in the ACNT, we also conducted an in situ X-ray absorption spectroscopic investigation at the Advanced Photon Source at Argonne National Laboratory. The oxidation state and coordination structure of the transition metals embedded inside the nanotubes were monitored by examining the EXAFS spectra collected under different polarization potentials. We clearly observed the change in the electronic and coordinational structures during the oxygen reduction reaction.},
doi = {10.1149/1.2728997},
journal = {ECS Transactions},
number = 1 ; 2007,
volume = 5,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • First, we utilized first-principles spin-polarized density functional theory (DFT) calculations to study the electrocatalytic reaction steps on FeN4/C site of carbon nanotubes. O 2 molecule can be adsorbed and partially reduced on FeN4/C site without any activation energy barrier. The partially reduced O 2 further reacts with H + and e - through a direct pathway (DPW) and form two water molecules without any activation energy barrier. Through an indirect pathway (IDPW), there is an activation energy barrier of ~ 0.15 eV for the formation of the first H 2O molecule. Finally, the formation of the second H 2O moleculemore » through IDPW does not have any activation energy barrier.« less
  • In situ EIS data are presented on the anodic process in proton exchange membrane (PEM) fuel cells and the influence of CO poisoning of the Pt gas-diffusion electrodes (GDE) is examined. A characterization of the effects of interfacial kinetics in determining polarization losses in the presence of CO is performed by comparing impedance patterns obtained for cells of the type H{sub 2}/H{sub 2} with H{sub 2}/(H{sub 2} + CO). The impedance spectrum of the poisoned electrode is strongly dependent on potential and on the CO concentration in the gas feed. In the range between 0 and 0.3 V the impedancemore » increases rapidly with the potential, while at potentials higher than 0.3 V a pseudoinductive behavior is observed, in which a positive loop at higher frequencies is accompanied by a low frequency (LF) loop in the fourth quadrant. The latter was assigned to a new rate-determining process, the oxidation of CO{sub ads} by Pt-H{sub 2}O{sub ads}. As a critical potential V{sub crit} is attained, the diameters of the two loops become almost equal and the LF limit of the impedance (R{sub o}) approaches the value for unpoisoned electrode, showing that the activity of the electrode activity has been restored. The value of V{sub crit} is 0.43 and 0.58 V for electrodes poisoned with 100 ppm and 2% CO, respectively. At very high potentials, where the oxidizing species are Pt-OH{sub ads}, the impedance pattern is reserved to the second and third quadrants. Stripping voltammetry and polarization curves recorded in situ, are used to support the conclusions obtained from impedance measurements.« less
  • The catalyst supports exhibit great influence on the cost, performance, and durability of polymer electrolyte membrane (PEM) fuel cells. This review paper is to summarize several important kinds of novel support materials for PEM fuel cells (including direct methanol fuel cell, DMFC): nanostructured carbon materials (carbon nanotubes/carbon nanofibers, mesoporous carbon), conductive doped diamonds and nanodiamonds, conductive oxides (tin oxide/indium tin oxide, titanium oxide, tungsten oxide) and carbides (tungsten carbides). The advantages and disadvantages, the acting mechanism to promote electrocatalysis, and the strategies to improve present catalyst support materials and to search for new ones are discussed. This is expected tomore » throw light on future development of catalyst support for PEM fuel cells.« less