Wednesday, November 7, 2007 - 9:10 AM
345c

A Cu/pt Near-Surface Alloy For Water-Gas Shift Catalysis

Anand U. Nilekar1, Jan Knudsen2, Ronnie T. Vang2, Joachim Schnadt2, Flemming Besenbacher2, and Manos Mavrikakis1. (1) University of Wisconsin, Department of Chemical & Biological Engineering, 1415 Engineering Dr. #2010, Madison, WI 53706, (2) Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, University of Aarhus, DK-8000, Aarhus C, Denmark

Water-Gas-Shift (WGS) reaction represents a crucial step in hydrogen production from fossil fuels and the performance of the current commercial catalysts used for WGS demands major improvement. Using of a combination of high-resolution scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), CO Temperature-programmed desorption (TPD) experiments, and density functional theory (DFT) calculations, we suggest the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA), promising for WGS catalysis. DFT calculations show that this Cu/Pt NSA binds CO, formate and other reaction intermediates significantly more weakly than Cu. We also find that this Cu/Pt NSA has a low activation barrier for H2O dissociation, the rate-determining step for the WGS on several metal surfaces. Thus, this NSA is resistant to poisoning by most prominent reactive intermediates, is very active for H2O activation, and -as a result- holds promise as an improved WGS catalyst.