Activity of CeOx and TiOx Nanoparticles Grown on Au(111) in the Water-Gas Shift Reaction
J. A. Rodriguez,1*
S. Ma,1
P. Liu,2
J. Hrbek,1
J. Evans,3
M. Pérez3
The high performance of Au-CeO2 and Au-TiO2 catalysts in the water-gas shift (WGS) reaction (H2O + CO
H2 + CO2) relies heavily on the direct participation of the oxide in the catalytic process. Although clean Au(111) is not catalytically active for the WGS, gold surfaces that are 20 to 30% covered by ceria or titania nanoparticles have activities comparable to those of good WGS catalysts such as Cu(111) or Cu(100). In TiO2-x/Au(111) and CeO2-x/Au(111), water dissociates on O vacancies of the oxide nanoparticles, CO adsorbs on Au sites located nearby, and subsequent reaction steps take place at the metal-oxide interface. In these inverse catalysts, the moderate chemical activity of bulk gold is coupled to that of a more reactive oxide.
1 Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
2 Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.
3 Facultad de Ciencias, Universidad Central de Venezuela, Caracas, 1020-A Venezuela.
* To whom correspondence should be addressed. E-mail: rodrigez{at}bnl.gov