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Strong Local Coordination Structure Effects on Subnanometer PtOx Clusters over CeO2 Nanowires Probed by Low-Temperature CO Oxidation
journal contribution
posted on 2015-09-04, 00:00 authored by Jun Ke, Wei Zhu, Yingying Jiang, Rui Si, Yan-Jie Wang, Shuai-Chen Li, Chuanhong Jin, Haichao Liu, Wei-Guo Song, Chun-Hua Yan, Ya-Wen ZhangA fundamental understanding of the
structural effects of supported metal catalysts at the molecular level
is extremely important for developing high-performance catalysts that
are widely used in industry, which is still a longstanding attractive
but challenging topic in multidisciplinary fields. In this work, we
report the strong effects of local coordination structures on the
catalytic activity of subnanometric PtOx clusters over CeO2 nanowires in low-temperature CO oxidation
as a probe reaction. Atoms and subnanometric clusters of Pt were deposited
to form the coordination structure of PtOx on the well-defined CeO2 nanowires with mainly exposed
(110) facets. The reactivity of active sites and the variation of
the local coordination structures of the PtOx sites were deeply investigated with in situ spectroscopic
experiments, assisted by density functional theory simulations. According
to our observation, although the highly dispersed Pt sites at the
subnanometric scale could provide increased accessible sites, some
of the Pt sites did not show high activity for CO oxidation due to
the increased surrounding oxygen that seemed to overstabilize the
Pt atoms. An increased proportion of both adsorbed CO intermediates
on oxidized Pt sites and the interfacial lattice oxygen of PtOx clusters tended to become inactive on samples
with a high coordination number of oxygen bonded to Pt sites (CN(Pt–O)),
leading to the loss of effective active sites and a decrease in the
catalytic activity. A relatively small CN(Pt–O) value in the
subnanometric PtOx/CeO2 NWs,
which was found to be the appropriate structure for their catalytic
performance, remarkably increased the activity by about 1/2 order
of magnitude. We believe our investigation on the interfacial coordination
structure effects of subnanometric PtOx clusters dispersed on CeO2 nanowires can provide some
new basic chemical insights into the metal–support interfacial
interactions of Pt/CeO2 catalysts for understanding their
catalytic performance in some relevant reactions.