Low concentration of active sites in the oxide support of catalysts may be blocked by the anchoring of metal particles. By using a second oxide as a support (host), one can create a multifunctional configuration with both metal and oxide active centers exposed to reactants. Deposition of an oxide on sub-monolayer amounts over a second oxide host can create nanostructures which in turn may enhance the overall catalytic properties of the entire system. We have synthesized Nanowires of RuOx on TiO2(110) by adsorption and decomposition of Ru3(CO)12 with subsequent exposure to O2 at elevated temperatures, and found a dramatic increase in their catalytic activity with respect to bulk ruthenium oxide. Depositing ceria on TiO2(110) leads to the formation of ceria dimmers. We uncovered an unexpected electronic influence, coined as 'electronic metal–support interaction' (EMSI), of these ceria dimers on the reactivity of small co-deposited platinum particles for reactions involving water cleavage. The importance of metal–oxide interfaces has long been recognized, but the molecular determination of their properties and role is only now emerging. Atoms with properties ranging from metallic to ionic are available at the metal–oxide interface and create unique reaction sites. Our studies point to a new paradigm in the design of catalysts: The optimization of the oxide phase and the metal-oxide interface in a catalyst can improve substantially its activity and selectivity. Examples on the catalytic properties of these mixed-metal oxides for photocatalytic and heterogeneous process will be presented.

Catalysis and the nature of mixed-metal oxides at the nanometer level: Special properties of MOx/TiO2(110) {M= Ru, Ce} surfaces

251st National Meeting (2016)

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