Experimental and Theoretical Studies of Novel Electrocatalysts

2010 Spring Symposium

 
Jingguang G. Chen
Center for Catalytic Science and Technology
Department of Chemical Engineering
University of Delaware
Newark, DE 19716


Abstract – Metal carbides [1-3] and bimetallic alloys [4-7] often show novel catalytic and electrocatalytic properties. However, it is difficult to know a priori how the chemical properties of particular carbide and bimetallic systems will be modified relative to the parent metals. In the past few years our research group has investigated the novel catalytic properties of various carbide and bimetallic systems, using a combination of Density Functional Theory (DFT) calculations, surface science studies on single crystal surfaces, and reactor and fuel cell studies of supported catalysts. The general trends from the experimental and theoretical studies of carbide [1] and bimetallic surfaces [4] have been summarized in recent reviews.

In this talk we will describe the utilization of tungsten carbides as potential anode electrocatalysts for Direct Methanol Fuel Cells (DMFC). Currently, the anode electrocatalysts for DMFC are Pt and Pt/Ru, which are disadvantageous in terms of the prohibitively high costs and their susceptibility to be poisoned by CO. We will describe how to control the decomposition pathways of methanol on single crystal surfaces of tungsten carbides under well-controlled ultrahigh vacuum (UHV) conditions. We will also discuss the synthesis of phase pure tungsten carbide electrodes using Physical Vapor Deposition (PVD) to bridge the “materials gap” between single crystal surfaces and polycrystalline films. We will then present our results of the electrochemical evaluation of the tungsten carbide electrodes to bridge the “pressure gap” between UHV environment and electrochemical conditions. We will also briefly discuss the thermodynamic stability and kinetic measurements regarding the bimetallic surfaces in the presence of oxygen under both UHV [8] and atmospheric [9] conditions, which should help identify active and stable bimetallic cathode electrocatalysts in the Oxygen Reduction Reaction (ORR) in fuel cells.

[1] Hwu & Chen, Chemical Reviews, 105 (2005) 185-212.
[2] Na, Zhang, Zheng, Wang & Chen, Angew. Chem. Int. Ed. 47 (2008) 8510.
[3] Weigert, Stottlemyer, Zellner & Chen, J. Phys. Chem. C, 111 (2007) 14617.
[4] Chen, Menning & Zellner, Surface Science Reports, 63 (2008) 201-254.
[5] Hwu, Eng & Chen, J. Am. Chem. Soc. 124 (2002) 702.
[6] Kitchin, Norskov, Barteau & Chen, Phys. Rev. Lett. 93 (2004) 156801.
[7] Murillo, Goda & Chen, J. Am. Chem. Soc. 129 (2007) 7101.
[8] Menning & Chen, J. Chem. Phys. 130 (2009) 174709.
[9] Menning & Chen, J. Power Sources, 195 (2010) 3140.

Speaker’s Biography – Jingguang Chen is the Claire D. LeClaire Professor of chemical engineering. He also holds the positions of the Interim Director of the University of Delaware Energy Institute and Co-Director of the Energy Frontier Research Center at the University of Delaware. He received his Ph.D. degree from the University of Pittsburgh 1988. He spent one year in Germany as a Humboldt Postdoctoral Fellow before starting his career at the Exxon Corporate Research Laboratories. In 1998 he accepted a faculty position at the University of Delaware and served as the Director of the Center for Catalytic Science and Technology (CCST) from 2000-2007. He has 200 journal publications and 17 US patents. He is very active in serving the surface science and catalysis communities, including responsibilities as the Chair for the Gordon Research Conference on Catalysis in 2002, the Chair of the Philadelphia Catalysis Club in 2004, the Catalysis Secretariat of the American Chemical Society in 2007, and the Board of Directors for the North American Catalysis Society. He is also the co-founder and team leader of the first Synchrotron Catalysis Consortium in the US for the Department of Energy.