Rapid synthesis of CuCeO2 catalysts by flame spray pyrolysis produces highly active Cu dimer morphologies without the need for additional catalyst pretreatment. The active Cu component is enriched onto the CeO2 surface at concentrations higher than the nominal loading with no evidence of amorphous or crystalline CuO phase. Increasing the Cu content results in a morphological transition from isolated Cu monomers to oxygen‐bridged dimers and an associated increase in oxygen vacancy concentration. Dimer‐containing CuCeO2 catalysts display high levels of activity and selectivity in the low‐temperature preferential oxidation of CO. Experimental measurements and simulations suggest that the geometry of the dimer presents a comparatively ionic CuO bond at the catalyst surface. Further studies indicate that these ionic dimer species promote preferential CO oxidation at lower temperatures than observed for monomeric Cu species. This is the first report to explicitly propose and demonstrate that the structural distortion associated with the formation of Cu dimers directly induces increased bond ionicity at the catalyst surface and that these changes are responsible for improved catalytic activity.

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A nonaqueous photodeposition procedure for forming Au nanoparticles on semiconducting supports (TiO(2), CeO(2), and ZrO(2)) was investigated. Intrinsic excitation of the support was sufficient to induce Au(0) nucleation, without the need for an organic hole-scavenging species. Photoreduction rates were higher over TiO(2) and ZrO(2) than over CeO(2), likely due to a lower rate of photogenerated electron recombination. Illumination resulted in metallization of the adsorbed Au species and formation of crystalline Au nanoparticles dispersed across the oxide surfaces. On the basis of transmission electron microscopy (TEM) evidence of a strong Au particle-metal oxide interaction, it is proposed that Au deposit formation proceeds via the nucleation of highly dispersed clusters which can diffuse and amalgamate at room temperature to form larger surface-defect-immobilized clusters, with the final particle size being significantly smaller than that achieved by conventional aqueous photodeposition. From this work, it is possible to draw several new fundamental insights, with regards to both the nonaqueous photodeposition process and the general mechanism by which dispersed metallic Au nanoparticles are formed from ionic precursors adsorbed upon metal oxide supports.

The influence of Cu on various metal oxide supports was investigated for the catalytic oxidation of acetaldehyde (ACA). The activity of the catalysts towards ACA conversion and the CO2 yield decrease in the order: Cu/CeO2>Cu/TiO2≈Cu/ZrO2> Cu/Al2O3>Cu/SiO2. Spontaneous adsorptive conversion of ACA to surface carboxylates, such as bridging and bidentate acetates, was detected over the basic supports CeO2, TiO2, and ZrO2. Detailed temperature‐programmed studies found the high activity of Cu/CeO2 to stem mainly from the intrinsically high activity of the CeO2 support. In contrast, similar studies on Cu/TiO2 demonstrated the activity improvements imparted by Cu were predominantly additive. Despite the difference in origin of ACA oxidation activity over Cu/CeO2 and Cu/TiO2, the overall concerted effects of basicity‐induced carboxylate formation and availability of surface oxygen were thought to be overriding factors crucial in the overall catalytic reactivity.

By identifying the Electron Partitioning Effect (EPE) as responsible for the large gold deposits usually formed in the conventional photodeposition method, a low energy UV light-based method for the preparation of comparatively high-activity gold-titania catalysts was developed. These materials were tested in the carbon monoxide (CO) oxidation reaction and returned markedly higher levels of activity at room temperature, when compared to catalysts prepared by the traditional photodeposition method. This is the first instance of using a light-mediated process for preparing catalysts active for the CO oxidation reaction.