CBET Award Achievements
Notable Accomplishments from CBET Awards
 

Dealloyed Core-Shell Alloy Nanoparticle Electrocatalysts for use in Electrochemical Energy Conversion

Peter Strasser  –  University of Houston


Background:  The proton-exchange membrane fuel cell (PEMFCs) is an energy conversion technology which has the potential to improve both environmental quality and energy security in the United States by converting hydrogen and oxygen from air into electricity and water.  The most critical technical challenges for fuel cell commercialization are the cost and poor performance of the carbon-supported Pt (platinum) catalyst.  More active and chemically stable fuel cell electrode catalysts would enable cost-effective and durable fuel cell devices.  A popular strategy to improve the performance of these fuel cells is to employ Pt alloys: non-noble transition metal atoms are introduced into the Pt lattice in the immediate neighborhood of Pt surface atoms, either in the first or in the second layer (bulk Pt alloys, Pt monolayer alloys).

Results:  Dr. Strasser's research group recently developed a class of very active oxygen reduction reaction (ORR) Pt-Cu (copper)nanoparticle electrocatalysts using a compositional analysis and surface scattering technique that de-alloys the Cu-rich precursor particles to yield a very Pt rich shell and Cu rich core (Figure 1).  The Pt enriched surface of this catalyst catalyzes the ORR with many times the efficiency (on a per unit-mass of Pt or per unit-surface of Pt basis) of pure platinum and with efficiencies exceeding the technological targets set by DOE.


Peter Strasser Image
Figure 1.  Use of electrochemical dissolution to dealloy the base metal rich precursor particles results in Pt surface enriched active ORR catalysts.
                   Keys:      a) full particle
                                   b) cross section.

              Colors:  Magenta  -  base metal atoms
                                         Grey  -  Pt atoms


Image Credit: Courtesy of Peter Strasser, University of Houston


Primary Strategic Outcome Goal:  (1) Discovery
  - Disciplinary/Interdisciplinary Research

Secondary Strategic Outcome Goal:  (2) Learning
  - Graduate and Undergraduate Education (in Sustainable Energy)

This project addresses the strategic outcome goals, as described in the NSF Strategic Plan 2006-2011, of:

(1) Discovery:  This research is directed at fundamental investigations whether electrocatalytic surface reactivity can be tuned by selective removal of surface base metal atoms thereby introducing a controlled amount of lattice strain.  Apart from its fundamental intellectual merit, it has the potential to transform today's catalyst technology for electrochemical energy conversion devices such as fuel cells, certain continuous batteries and other devices.

(2) Learning:  Dr. Strasser's research and teaching on ‘material science for energy’ introduce undergraduate and graduate students at the University of Houston to concepts and methods of electrochemistry-enabled nanotechnology.  To disseminate knowledge and encourage learning about sustainable energy technologies, he organized trips for K-12 student groups to visit to the Houston Museum of Natural Science’s unique Wiess Energy Hall followed by visits to the PI’s Electrochemical Energy and Fuel Cell Laboratories.  During these face-to-face events, K-12 students were encouraged to discuss and reflect on the importance of sustainable energy technologies.

This research is notable because of Scientific Uniqueness:  This hypothesis-driven project investigates the fundamental role of geometric strain in nanostructured core-shell alloy particles.  The synthesis of the active catalyst phase involves deliberate removal of metal atoms from the alloy particle surface (corrosion) which is a novel, counter-intuitive concept. Harnessing corrosion as a synthetic strategy for new materials has begun to interest theoretical-computational researchers in the field of surface catalysis.  Introduction of controlled amount of lattice strain may prove to be a new deliberate strategy to tune surface catalytic activity.

Transformative Research:  The unprecedented reactivity of de alloyed Pt core-shell nanoparticles for the electroreduction of oxygen in fuel cell tests to date has verifiably shown that a broader use of this catalyst class could reduced the (noble metal) cost of a fuel cell by up to a factor of 6x, which is discussed as the target value for automotive fuel cell commercialization.  No other fuel cell cathode alloy catalyst class to date has shown this level of activity in a single fuel cell.  Given the stability of the catalysts is acceptable, this class of catalytic materials could transform the current fuel cell cathode catalyst technology.

Broadening Participation:  The University of Houston is a Department of Education-designated Minority Post-secondary Institution; more than half of the undergraduate students at UH are minorities.  The PI has and continues to recruit minority undergraduate summer students by means of the Program of Mastery in Engineering Studies (PROMES) offered in the UH College of Engineering.  This is a program focusing on student retention and advancement, and the UH-led, NSF-sponsored Houston Louis Stokes alliance for minority participation.  This program, a collaborative effort of six universities including Texas Southern University, two community college systems and the Houston Independent School District, is designed to double in five years the number of baccalaureate degrees granted annually to under-represented minority students in the fields of science, mathematics, engineering, and technology.

Impact on Industry and/or Society:  The discovered class of electrocatalytic materials has the potential to significantly reduce the cost of hydrogen fuel cell technology to levels where commercialization of fuel cells for automotive applications becomes economically viable.  A broader use of all electric fuel cell-powered vehicles would spur the development of hydrogen technologies, catalyze the transition to a broader use of hydrogen as an energy carrier in transportation, co-catalyze the use of stationary fuel cells as residential power source, and, as a consequence, would contribute to a reduction of the US dependence on foreign oil imports.



     
Program Officer:
 
  Trung Van Nguyen
CBET Program Director, Energy for Sustainability
     
NSF Award Number:   0729722
     
Award Title:   Lattice-strained core-shell nanoparticle catalysts for use in electrochemical energy conversion
     
PI Name:   Peter Strasser - University of Houston
     
Program Element:   7644
     
NSF Investments:
 
 
 
 
  American Competitiveness Initiative (ACI)
Climate Change
Homeland Security
National Nanotechnology Initiative (NNI)
Environment (including the importance of fresh water and dynamics of water processes)
     
CBET Nugget:   FY 2008
     

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This Nugget was Updated on 28 November 2008.