Ceria has been widely studied as an oxidation-reduction catalyst due to its unique redox properties and oxygen storage capacity. Metal dopants such as Ti and Mn can be incorporated into ceria and form dopant-ceria mixed oxides, which could better enhance its thermal stability and improve its redox properties and oxygen storage capacity for practical applications in catalysis. To understand the chemistry of the metal dopant-ceria catalytic systems, we examined their structures at the nano-scale using X-ray photoelectron spectroscopy, low-energy electron diffraction, as well as scanning tunneling microscopy. Ti and Mn were vapor-deposited onto well-ordered ceria overlayers with a (111) surface orientation under ultrahigh vacuum conditions. Upon deposition of a sub-monolayer coverage at room temperature, both Mn and Ti are oxidized at the cost of ceria reduction. Ti is in the +4 formal oxidation state. However, +2 state of Mn is the predominate species on ceria. STM data show the presence of atomic-high features at the interface at 300 K as a result of formation of metal dopant-O-Ce linkages, which can further develop into two-dimensional chain structures or triangular domains upon heating. Our studies have shown that deposition of Ti and Mn metal dopants can modify both structural and electronic properties of ceria, which exhibit interesting chemical behavior upon adsorption of CO and O2 molecules. Furthermore, the addition of Ti/Mn dopants into ceria can affect the dispersion, stability, morphological, and electronic properties of deposited metal nanoparticles such as Au and Ni. The research is sponsored by the National Science Foundation (Award Number: CHE1151846).

Structure and properties of metal dopant/ceria mixed oxide interfaces

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.