Nanostructured Bimetallic, Trimetallic and Core-Shell Fuel-CellNanostructured Bimetallic, Trimetallic and Core-Shell Fuel-CellCatalysts with Controlled Size, Composition, and MorphologyCatalysts with Controlled Size, Composition, and Morphology

(NIRT (NIRT CBET-0709113CBET-0709113))Jin LuoJin Luo11, Bin Fang, Bin Fang11, Bridgid Wanjala, Bridgid Wanjala11, Rameshwori Loukrakpam, Rameshwori Loukrakpam11, Peter N. Njoki, Peter N. Njoki11, Xiajing Shi, Xiajing Shi11, Derrick Mott, Derrick Mott11, Susan Lu, Susan Lu22, Lichang Wang, Lichang Wang44, Bahgat Sammakia, Bahgat Sammakia33, , Chuan-Jian ZhongChuan-Jian Zhong11**

Department of Department of 11Chemistry, Chemistry, 22Systems Science and Industrial Engineering, Systems Science and Industrial Engineering, 33Mechanical Engineering, Mechanical Engineering, State University of New York at Binghamton, Binghamton, NY 13902, USA State University of New York at Binghamton, Binghamton, NY 13902, USA

44Department of Chemistry & Biochemistry, Southern Illinois University at Carbondale,Department of Chemistry & Biochemistry, Southern Illinois University at Carbondale, IL 62901, USA IL 62901, USAAbstract: 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 Nano-engineering of Multimetallic Catalysts

Spot Pt V Fe10 (area) 34 16 50

11 (3nm) 34 16 50

12 (3nm) 33 15 52

13 (6nm) 32 13 55

Composition 32 13 55

PtVFe /C

For More Information:Email: * C.J. Zhong: cjzhong@binghamton.edu; Web: http://chemistry.binghamton.edu/ZHONG/zhong.htm

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.

Activity and Durability in Fuel cells

SupportReferences1. 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.

Stability

Activity

DFT Calculation

Pareto optimization

Morphology, Phase, and Composition

Fuel cell voltage:

Ecell = ENernst + ηact – ηohmic

AunPt100-n/C

(ORR: Oxygen Reduction Reaction)

Optimal balanced activity and stability.e.g., (Ni)x(Zr)yPt1-x-y

• Reduce Pt loading• Increase activity & stability• Understand design parameters • Discover new catalysts ηact=ηact(cathode)-ηact(anode))

Goals:

Bimetallic and Trimetallic Catalysts

• High conversion efficiency• Low pollution• Light weight• High power density

NIRTNIRTSUNYSUNY

NIRTNIRT

AuPt /C

Fuel Cells:

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).

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))

Computation and Optimization

Pt /C

Core@Shell Catalysts

Au@Pt

AuPt /C

ORR

Comparison of mass activities and specific activities for carbon-supported monometallic, bimetallic and trimetallic catalysts (E = 0.858 V vs. RHE).

Au@Pt/C