Low-Platinum Nanostructured Catalysts for Fuel Cells. Karen Swider-Lyons and Peter Bouwman Naval Research Laboratory Washington, DC Wojtek Dmowski University of Tennessee Knoxville, TN. 14. Source: Transportation Energy Data Book: Edition 19 , DOE/ORNL-6958, September 1999, and
Source: Transportation Energy Data Book: Edition 19, DOE/ORNL-6958, September 1999, and
EIA Annual Energy Outlook 2000, DOE/EIA-0383(2000), December 1999
Domestic Oil Production
Millions of Barrels per Day
U.S. Transportation Oil Demand
Strategies needed to close the production/utilization gap
Use fuel cells to increase efficiency and decrease fuel consumption
Electrochemical conversion process
Oxygen and hydrogen combined on catalysts to produce water, electricity and heat
H2 = 2 H+ + 2 e-
O2 + 2 H+ + 2 e- = H2O
Resistive losses due to materials and inefficient reactions.
Proton exchange membrane fuel cell
Perfluorosulfonic acid (Nafion® polymer) membrane
Hydrogen from water electrolysis is expensive due
to high materials and energy costs of electrolyzers
Mining Pt creates a lot of waste!
In fuel cell era, attention toward environmentally friendly mining and recycling
From: The Lonmin Group web site
Lowering Pt will lower the cost of fuel cells
Nanocomposite phases are still largely unexplored
-due to difficulty in their characterization?
Pt supported on MOx•H2O supported on carbon
O2 + 4 H+ + 4e- 2 H2O
Support Pt on a metal oxide and
improve opportunity for
* proton mobility to Pt sites
* chem/phys attraction of O2
* metal-support interactions with Pt
Catalyst development via
electrochemical and structural analysis
“Open Framework Inorganic Materials”
A. K. Cheetham G. Férey, T. Loiseau,
Angew. Chem. 1999, v. 38 p. 3286.
Pt-FePO4 catalysts have higher ORR activity than Pt/carbon standard
9% Pt-FePOx•yH2O + 50% VC
0.1 M HClO4
Structure of the active Pt-FeO
sample is glassy in conventional electron microscopy and X-ray diffraction
XRD largely amorphous
X-ray or neutron scattering is Fourier-transformed to give distribution of inter-atomic distances in a real space.
High energy, high intensity sources are essential to minimize errors and improve statistics.
Structure of Pt-FePOx with PDF analysis
VC impregnated with Pt-FePOx
Pt-FePOx mixed with Vulcan carbon
vs. Pt-FePOx impregnated on Vulcan carbon