Transcript NSF NIRT 08 Meeting - NSF Nanoscale Science and

SUNY
Nanostructured Bimetallic, Trimetallic and Core-Shell Fuel-Cell
Catalysts with Controlled Size, Composition, and Morphology
(NIRT CBET-0709113)
NIRT
Jin Luo1, Bin Fang1, Bridgid Wanjala1, Rameshwori Loukrakpam1, Peter N. Njoki1, Xiajing Shi1, Derrick Mott1, Susan Lu2, Lichang Wang4, Bahgat Sammakia3, Chuan-Jian Zhong1*
1Chemistry, 2Systems
3Mechanical
Department of
Science and Industrial Engineering,
Engineering,
State University of New York at Binghamton, Binghamton, NY 13902, USA
4Department of Chemistry & Biochemistry, Southern Illinois University at Carbondale, IL 62901, USA
Abstract:
One of the most important challenges for the ultimate commercialization of fuel cells is the preparation of active, robust and low-cost catalysts. This poster highlights recent development of our investigations of
nanostructured catalysts in addressing this challenge. Emphasis is placed on nanoengineering-based fabrication, processing, and characterization of multimetallic nanoparticles. Recent results from evaluating the electrocatalytic
performance of the nanoengineered catalysts in fuel cell reactions are discussed. The nanoengineering approach differs from other traditional approaches to the preparation of supported catalysts in the ability to control the particle size,
composition, phase and surface properties. The understanding of how the nanoscale properties of the multimetallic nanoparticles differ from their bulk-scale counterparts, and how the interaction between the nanoparticles and the support
materials relates to the size sintering or evolution in the thermal activation process is an important focus. The fact that the bimetallic gold-platinum nanoparticle system displays the single-phase character different from the miscibility gap
known for its bulk-scale counterpart serves as an important indication of the nanoscale manipulation of the structural properties, which are useful for refining the design and preparation of the bimetallic catalysts. Bimetallic (PtnM1100-n),
trimetallic (PtnM1mM2100-n-m) nanoparticles (M (1 or 2) = Pt, Co, Ni, V, Fe, Cu, Pd, Cr, W, Zr, Au, etc.) were studied for establishing the structure-activity correlation. The fact that the some of the nanoengineered multimetallic nanoparticle
catalysts exhibit electrocatalytic activities in fuel cell reactions which are 4~5 times higher than pure Pt catalysts constitutes the basis for further expansion to the exploration of a variety of multimetallic combinations. The fundamental
insights into the control of nanoscale alloy, composition and core-shell structures have important implications to identifying nanostructured fuel cell catalysts with an optimized balance of catalytic activity and stability.
Fuel Cell Catalysts and Electrocatalytic Activity
Morphology, Phase, and Composition
Nano-engineering of Multimetallic Catalysts
PtVFe /C
AuPt /C
Fuel Cells:
• High conversion efficiency
• Low pollution
• Light weight
• High power density
Fuel cell voltage:
Goals:
• Reduce Pt loading
• Increase activity & stability
• Understand design parameters
• Discover new catalysts
Spot
Pt
V
Fe
10 (area)
34
16
50
11 (3nm)
34
16
50
12 (3nm)
33
15
52
13 (6nm)
32
13
55
Composition
32
13
55
AunPt100-n/C
Ecell = ENernst + ηact – ηohmic
Pt /C
ηact=ηact(cathode)-ηact(anode))
Bimetallic and Trimetallic Catalysts
Core@Shell Catalysts
Computation and Optimization
Activity and Durability in Fuel cells
DFT Calculation
Au@Pt
(ORR:
Oxygen Reduction Reaction)
AuPt /C
RDE curves for Pt32V14Fe54/C
(31% M) and Pt31Ni34Fe35/C
(30% M) in comparison with
standard Pt/C (36% M) (A, 5
mV/s, 2000 rpm), and for alloy
Au23Pt77/C (15%Pt) in 0.5 M
H2SO4. (B, 10 mV/s, 1600 rpm).
ORR
Au@Pt/C
Comparison of mass activities and specific
activities for carbon-supported
monometallic, bimetallic and trimetallic
catalysts (E = 0.858 V vs. RHE).
Pareto optimization
Activity
Polarization and power density curves of
MEA with Pt42V19Fe39/C or Pt/C as
cathode in PEMFC at 75 ○C (21% M, 0.4
mgPt/cm2)
(Anode: Pt/C catalyst (20% Pt, E-tek, 0.4
mgPt/cm2))
Optimal balanced
activity and stability.
e.g., (Ni)x(Zr)yPt1-x-y
Stability
Summary
• Nano-engineered bimetallic, trimetallic, and core-shell nanoparticle catalysts with
controlled size, composition and phase properties have been shown to exhibit high
electrocatalytic activity (4~5 times higher than pure Pt catalysts).
• Experimental and theoretical results have shown that the size, composition,
phase, and surface properties of multimetallic nanoparticles play an important role
in determining the electrocatalytic activity and stability.
• Promising multimetallic nanocatalysts are being identified as promising catalysts
under fuel cell conditions in terms of activity and durability.
References
1. B. Fang, J. Luo, P. N. Njoki, R. Loukrakpam, D. Mott, B. Wanjala, X. Hu, C. J. Zhong,
Electrochem. Comm., 2009, 11, 1139–1141.
2. Zhong, C. J.; Luo, J.; Njoki, P. N.; Mott, D.; Wanjala B.; Loukrakpam, R.; Lim, S. I-I.; Wang, L.;
Fang, B.; Xu, Z., Energy & Environ. Sci, 2008, 1, 454.
3. J. Luo, L.Y. Wang, D. Mott, P. Njoki, Y. Lin, T. He, Z. Xu, B. Wanjala, S. I-Im Lim, C. J. Zhong, Adv.
Mater., 2008, 20, 4342.
For More Information:
Email: * C.J. Zhong: [email protected]; Web: http://chemistry.binghamton.edu/ZHONG/zhong.htm
Support
NIRT