Anode materials for low-temperature fuel cells: A density functional theory study

Based on density functional calculations, we discuss the effect of alloying Pt with other metals for use as anode catalyst materials in low-temperatur e fuel cells. We discuss why a few parts per million of CO in the H-2 fuel can poison Pt surfaces and how this problem can be alleviated by alloying, and an extensive data base of the effect of alloying on the reactivity that includes all binary combinations of the transition metals to the right in the periodic table is given. We also discuss the effect of surface segregat ion and give a calculated data base of segregation energies of binary trans ition metal alloys. Based on extensive Monte Carlo simulations we show that while the adsorbate-free surface of a Ru0.5Pt0.5 alloy has no Ru in the fi rst layer, the presence of CO can move some Ru to the surface, but all thes e Ru atoms are covered by CO. (C) 2001 Academic Press.