DFT study of synergistic catalysis of the water-gas-shift reaction on Cu-Au bimetallic surfacesDFT study of synergistic catalysis of the water-gas-shift reaction on Cu-Au bimetallic surfaces
Faculty of Sciences. Physics
Condensed Matter Theory
8(2016):6, p. 1208-1217
University of Antwerp
The water-gas-shift reaction (WGSR) is an important industrial process that can be significantly enhanced at suitable catalyst surfaces. In this work, we investigate the catalytic behavior of metallic Cu(100) and bimetallic Cu-Au(100) surfaces. With density functional theory calculations, the variation in the Gibbs free energy (G degrees), the activation barriers, and the rate constants for the WGSR are calculated. The variation in G degrees for water dissociation shows that the process is spontaneous up to 520K on the bimetallic surface and up to 229K on the Cu(100) surface. The calculated rate constants for the process also show that the bimetallic surface is much more reactive than the Cu(100) surface. The calculated pressure-temperature phase diagram for water dissociation shows that the partial pressure of H2O required for water dissociation on the bimetallic surface is substantially lower than that on the Cu(100) surface at all the studied temperatures. Additionally, the calculations demonstrate that the kinetics of the water-gas-shift reaction is dominated by redox processes on both the surfaces.