Surface Chemistry of Model Oxide-Supported Metal Catalysts: An Overview of Gold on Titania

CO Oxidation on Au/TiO2: Condition-Dependent Active Sites and Mechanistic Pathways

“…Given the above results we ask whether or not O ad Au + CO is active toward CO oxidation, or thermodynamically stable, hence potentially a step toward catalyst deactivation as has been debated in the literature. − Two major CO oxidation mechanisms have been previously proposed. In the LH mechanism, the first CO molecule on the gold cluster reacts with the adsorbed O 2 to produce the first CO 2 molecule, leaving one O ad at the metal/oxide interface.…”

“…Only a few kinetic studies ,,,− have been performed to obtain apparent activation energies for CO oxidation on Au/TiO 2 ; the values vary from 0.2–0.8 eV with the notable observation that the highest activation energies are obtained under highly oxidizing conditions. See the summarized information in Table S6.…”

“…Given our results, we postulate that apparent activation energies strongly depend on the catalyst preparation method and the level of oxidation of the catalyst/support under operando conditions. Most studies point out that Au/TiO 2 nanocatalysts exhibit a high activity for CO oxidation with a barrier of ∼0.2–0.4 eV at low temperatures. ,,, However, it was also reported that catalysts often deactivated very rapidly within only 1–2 h. Goodman et al, , attributed the deactivation to Au cluster agglomeration, but the estimated activation energy only changed by 0.1 eV, when the size of the Au cluster changed from 3 to 6 nm. Moreover, Behm et al, pointed out that size effects could not be the main deactivation culprit due to the observed small changes in particle size.…”

Investigating Reactive Superoxide Units Bound to Zirconium Oxide Cations

“…Relationships among the elemental composition, electronic structures, and geometric structures correlate to specific chemical transformations and catalytic processes. 1 The remarkable oxidative ability of catalytic materials is due to their capacity to activate oxygen on their surfaces. Findings from a detailed investigation of the reactivity of various forms of activated oxygen are expected to provide information that may enable the tailored design of highly selective and active oxidation catalysts.…”

“…Currently, considerable interest in catalytic research is focused on determining the active sites responsible for promotion of catalytic mechanisms. Relationships among the elemental composition, electronic structures, and geometric structures correlate to specific chemical transformations and catalytic processes . The remarkable oxidative ability of catalytic materials is due to their capacity to activate oxygen on their surfaces.…”