title: Water-gas shift reaction on metal nanoclusters encapsulated in mesoporous ceria studied with ambient-pressure X-ray photoelectron spectroscopy.
abstract: Metal nanoclusters (Au, Pt, Pd, Cu) encapsulated in channels of mesoporous ceria (mp-CeO(2)) were synthesized. The activation energies of water-gas shift (WGS) reaction performed at oxide-metal interfaces of metal nanoclusters encapsulated in mp-CeO(2) (M@mp-CeO(2)) are lower than those of metal nanoclusters impregnated on ceria nanorods (M/rod-CeO(2)). In situ studies using ambient-pressure XPS (AP-XPS) suggested that the surface chemistry of the internal concave surface of CeO(2) pores of M@mp-CeO(2) is different from that of external surfaces of CeO(2) of M/rod-CeO(2) under reaction conditions. AP-XPS identified the metallic state of the metal nanoclusters of these WGS catalysts (M@mp-CeO(2) and M/rod-CeO(2)) under a WGS reaction condition. The lower activation energy of M@mp-CeO(2) in contrast to M/rod-CeO(2) is related to the different surface chemistry of the two types of CeO(2) under the same reaction condition.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Cun
authors.initials: C
authors.lastname: Wen
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Ye
authors.forename: Shiran
authors.initials: S
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Cheng
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Paul
authors.initials: P
authors.lastname: Wang
authors.forename: Franklin Feng
authors.initials: FF
authors.lastname: Tao
mesh_terms: D002563:Cerium / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D044367:Phase Transition; D056951:Photoelectron Spectroscopy / Q000379:methods*; D016062:Porosity; D011312:Pressure; D014867:Water / Q000737:chemistry*
chemical_list: D005740:Gases; D014867:Water; D002563:Cerium; C030583:ceric oxide