CO Oxidation Promoted by a Pt4/TiO2 Catalyst: Role of Lattice Oxygen at the Metal/Oxide Interface

Atomic and Electronic Structure of Pt/TiO2 Catalysts and Their Relationship to Catalytic Activity

Understanding the nature of the interaction between a metal and support, which is known as the metal-support interaction, in supported metal catalysts is crucial to design catalysts with desired properties. Here, we have developed model Pt/TiO₂ catalysts based on the deposition of colloidal Pt nanoparticles and studied their atomic and electronic structures before and after a postdeposition treatment that induces catalytic activity using aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles calculations. Direct contact between Pt nanoparticles and TiO₂ is realized after the postdeposition treatment, which is accompanied by the formation of a Ti³⁺ state on the TiO₂ surface close to the Pt nanoparticles and a Pt^δ+ state on the Pt nanoparticles. The origin of these two states and their effect on the catalytic properties are discussed. These findings pave the way for a comprehensive understanding of metal-support interactions in supported metal catalysts.

CO Oxidation at Near-Ambient Temperatures over TiO2-Supported Pd-Cu Catalysts: Promoting Effect of Pd-Cu Nanointerface and TiO2 Morphology

Significant improvement of the catalytic activity of palladium-based catalysts toward carbon monoxide (CO) oxidation reaction has been achieved through alloying and using different support materials. This work demonstrates the promoting effects of the nanointerface and the morphological features of the support on the CO oxidation reaction using a Pd-Cu/TiO2 catalyst. Pd-Cu catalysts supported on TiO2 were synthesized with wet chemical approaches and their catalytic activities for CO oxidation reaction were evaluated. The physicochemical properties of the prepared catalysts were studied using standard characterization tools including SEM, EDX, XRD, XPS, and Raman. The effects of the nanointerface between Pd and Cu and the morphology of the TiO2 support were investigated using three different-shaped TiO2 nanoparticles, namely spheres, nanotubes, and nanowires. The Pd catalysts that are modified through nanointerfacing with Cu and supported on TiO2 nanowires demonstrated the highest CO oxidation rates, reaching 100% CO conversion at temperature regime down to near-ambient temperatures of ~45 °C, compared to 70 °C and 150 °C in the case of pure Pd and pure Cu counterpart catalysts on the same support, respectively. The optimized Pd-Cu/TiO2 nanowires nanostructured system could serve as efficient and durable catalyst for CO oxidation at near-ambient temperature.

A DFT and microkinetic study of propylene oxide selectivity over copper-based catalysts: effects of copper valence states

The development of high-performance copper-based catalysts is critical for the selective oxidation of propylene in both technology and scientific fields.