| Sumario: | We present a simple and generalizable synthetic route toward phasepure, monodisperse transition-metal-substituted ceria nanoparticles (MCeC, M = Mn, Fe, Co, Ni, Cu). The solution-based pyrolysis of a series of heterobimetallic Schiff base complexes ensures a rigorous control of the size, morphology and composition of 3 nm MCeC crystallites for CO oxidation catalysis and other applications. X-ray absorption spectroscopy confirms the dispersion of aliovalent (M and M) transition metal ions into the ceria matrix without the formation of any bulk transition metal oxide phases, while steady-state CO oxidation catalysis reveals an order of magnitude increase in catalytic activity with copper substitution. Density functional calculations of model slabs of these compounds confirm the stabilization of M and M in the lattice of CeO. These results highlight the role of the host CeO lattice in stabilizing high oxidation states of aliovalent transition metal dopants that ordinarily would be intractable, such as Cu, as well as demonstrating a rational approach to catalyst design. The current work demonstrates, for the first time, a generalizable approach for the preparation of transition-metal-substituted CeO for a broad range of transition metals with unparalleled synthetic control and illustrates that Cu is implicated in the mechanism for CO oxidation on CuO-CeO catalysts.
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