Tuning the Surface Chemical Reactivity of Oxides for Heterogeneously Catalyzed Organic Synthesis

Cheap and abundant ionic solids, like transition-metal oxides, carbides, and nitrides, exhibit tunable surface chemical reactivity and a dual-site nature not found on classic reduced-metal heterogeneous catalysts.  Specifically, the chemical reactivity of the surface anion site is of chief interest as it presents a new catalytic site with drastically different and tunable chemical properties distinct from cationic metal surface sites.  In our efforts to rationally design heterogeneous catalytic materials for organic synthesis reactions, we have found that the reactivity of oxygen plays a critical role in the surface reaction mechanism.  In this presentation, we will discuss the role of CeO₂ in the phosgene-free synthesis if urethane monomers and AuO_x/CeO₂ in the Sonogashira carbon-carbon coupling reaction.  Utilizing a combination of DFT calculations, crystal-morphology-directed nano-crystal synthesis, and spectroscopy, we determined surface reaction mechanisms and rationally designed improved catalytic materials.