posted on 2017-11-20, 00:00authored byYa-Qiong Su, Ivo A. W. Filot, Jin-Xun Liu, Emiel J. M. Hensen
Doping
CeO2 with Pd atoms has been associated with catalytic
CO oxidation, but current surface models do not allow CO adsorption.
Here, we report a new structure of Pd-doped CeO2(111),
in which Pd adopts a square planar configuration instead of the previously
assumed octahedral configuration. Oxygen removal from this doped structure
is favorable. The resulting defective Pd-doped CeO2 surface
is active for CO oxidation and is also able to cleave the first C–H
bond in methane. We show how the moderate CO adsorption energy and
dynamic features of the Pd atom upon CO adsorption and CO oxidation
contribute to a low-barrier catalytic cycle for CO oxidation. These
structures, which are also observed for Ni and Pt, can lead to a more
open coordination environment around the doped-transition-metal center.
These thermally stable structures are relevant to the development
of single-atom catalysts.