DFT Study of the CO Poisoning Effects on PdxCu1-x (110) Surface
CO contaminants play a significant role in modifying the performance of proton exchange membrane fuel cells (PEMFC). Pt is probably the most common catalyst being used today to absorb CO in the PEMFC, yet recent studies have shown that the use of Pd alloys such as Pd-Cu can increase the fuel cell efficiency versus a pure Pt catalyst. In this work, we examine the adsorption of CO onto PdxCu1-x (110) surfaces, with different values of x, in order to improve the CO tolerance. Understanding how molecules interact with such surfaces is the first step in understanding catalytic reactions. The study here presented was done using CASTEP, a computational code based on the plane-wave pseudopotential method of functional density theory. The surface structure of PdxCu1-x (110) was optimized and then the state density-functional, the repulsion energies and the chemisorption for CO on PdxCu1-x(110) were calculated. The results indicate that chemisorption energies of CO on PdxCu1-x are highly dependent on the concentration x of the alloy. In addition, density of states analysis indicate that the poisoning effect is partially due to the loss of Pd-Cu(d) electrons upon CO adsorption.
catalysts, CO poisoning, PEMF cell, molecular simulation, DFT theory
Project supported by the Institute of Science and Technology of DF (ICYT-DF), under the agreement PIUTE10-32. We also acknowledge, for the partial finantial support, to Sistema Nacional de Investigadores from Consejo Nacional de Ciencia y Tecnología
(Mexican government foundation), SNI-CONACyT and to the Universidad Autónoma de la Ciudad de México, UACM.
 B.C.H. Steele, A Heinzel, Nature, 414, 345 (2001).
 R. Bashyam, P. Zelenay, Nature, 443, 63 (2006).
 F. Barbir. PEM fuel cells: theory and practice. New York: Elsevier Academic Press, 2005.
 R.G. Herman, K. Klier, G.W. Simmons, B.P. Finn, J.B. Bulko, T.P. Kobylinski, J. Catal. 56, 407 (1979).
 S. Alayoglu, A.U. Nilekar, M. Mavrikakis, B. Eichhorn, Nat. Mater. 7, 333 (2008).
 X. Cheng, Z. Shi, N. Glass, L. Zhang, J. Zhang, D. Song, Z. Liu, H. Wang, J.J. Shen, Power Sources, 165, 739 (2007).
 M.M. Gadgil, R. Sasikala, S.K. Kulshreshtha, J. Mol. Catal., 87 (1994).
 S. Ye, P. Beattie, S.A. Campbell, D.P. Wilkinson. Anode catalyst compositions for a voltage reversal tolerant fuel cell. US Patent Appl. 2004/0013935.
 T.R. Ralph, M.P. Hogarth, Platinum. Metals. Rev., 46, 117 (2002).
 S.D. Knights, K.M. Colbow, J. St-Pierre, D.P. Wilkinson. J. Power Sources, 127 (2002).
 R.L. Borup, J.R. Davey, F.H. Garzon, D.L. Wood, M.A Inbody, J. Power Sources, 163, 76 (2006).
 S. Ye, M. Hall, H. Cao, P. He, ECS Transactions 3,1, 657 (2006).
 Web page: www.kitco.com/market/.
 K. Kinoshita, Electrochemical Oxygen Technology, Wiley: New York, 1992.
 J.L. Fernandez, V. Raghuveer, A. Manthiram, A. Bard, J. Am. Chem. Soc. 127, 13100 (2005). A. Sarkar, A.V. Murugan, A. Manthiram, J. Mater. Chem. 19, 159 (2009).
 T.D. Pope, K. Griffiths, P.R. Norton, Surf. Sci, 306, 30 (1994).
 L. Bellaiche, D. Vanderbilt, Phys. Rev. B, 61, 7877 (2000).
 Web page: www.accelrys.com
 P. Hohenberg, W. Kohn, Phys. Rev. B, 136, 864 (1964).
 W. Kohn, L. Sham, J, Phys. Rev. A, 140, 1133 (1965).
 M. Levy in Proc. Natl. Acad. Sci. U. S. A., 76, 6062 (1979).
 R.G. Parr, W. Yang, Density-Functional Theory of Atoms and Molecules, Oxford University Press, Oxford, 1989.
 E.S. Krychko, E.V. Ludena. Energy Density Functional Theory of Many-Electron Systems, vol. 4 of Understanding Chemical Reactivity, Kluwer Academic Publishers, Dordrecht, 1990.
 B.G. Pfrommer, M. Cote, S.G. Louie, M.L. Cohen, J. Comput. Phys., 131, 133 (1997).
 J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 77, 3865 (1996).
 X. Xu, W. Goddard III, J. Chem. Phys., 121, 9 (2004).
 L. Chen, B. Chen, CH. Zhou, R. Forrey, H.J. Cheng, J. Phys. Chem. C., 112, 1394 (2008).
 G.J. Blyholder, J. Phys. Chem., 68, 2772 (1964).
 X.Wang, N.N, Kariuki, S.M. Niyogi, D.J. Smith, T. Myers, Y. Hofmann, M. Zhang and C. Heske, 214th ECS Meeting, October 12–17, Honolulu, Hawaii, 2008.
 Y. Sha, T. Yu, B.V. Merinov, A. van Duin, and W.A. Goddard III, 214th ECS Meeting, October 12–17, Honolulu, Hawaii, 2008.