Transformation of a Pt–CeO₂ Mechanical Mixture of Pulsed‐Laser‐Ablated Nanoparticles to a Highly Active Catalyst for Carbon Monoxide Oxidation

Abstract

The pulsed laser ablation (PLA) in alcohol and water media was employed to prepare Pt and CeO2 PLA‐nanoparticles of different sizes and degrees of defectiveness. Interactions of metallic platinum and ceria particles were studied using the thermal activation of Pt–CeO2 mechanical mixtures in the CO+O2 reaction medium or O2 atmosphere. The thermal activation resulted in oxidized Pt2+/Pt4+ states of platinum in the surface solid solutions PtCeOx and/or PtOx clusters. Catalysts formed after calcination of the PLA‐ablated Pt–CeO2 mixtures in oxygen at 450–600 °C revealed CO conversion at very low temperatures up to 70 % depending on the conditions of PLA particles preparation and thermal activation of Pt–CeO2 mechanical mixture.

Cerium(III) Nitrate Derived CeO2 Support Stabilising PtOx Active Species for Room Temperature CO Oxidation

“…Interestingly, the analogous effect (non‐zero activity below 25 °C, GHSV=50 000 ml ⋅ g −1 ⋅ h −1 ) was shown for 2.5 wt% Pt/CeO 2 catalyst for which the tetrahedral platinum clusters Pt 4 grafted on the ceria surface were proposed to be active centres. An even more pronounced effect (converting up to 70 % CO at 25 °C, GHSV=200 000 ml ⋅ g −1 ⋅ h −1 ) was achieved for Pt/CeO 2 catalysts prepared by pulsed laser ablation and activated in oxygen at 450–600°C . The low‐temperature activity was attributed to the formation of oxidised platinum species, such as PtO x clusters and surface solid solutions of platinum ions in ceria.…”

“…The spectrometer was calibrated using the Au4f 7/2 (84.0 eV) and Cu2p 3/2 (932.7 eV) lines of pure gold and copper metallic surfaces. Spectral calibration for the samples was performed using binding energy E b (Ce3d U′′′)=916.7 eV . The chemical composition was calculated from the XPS data, taking into account atomic sensitivity factors .…”

“…Spectral calibration for the samples was performed using binding energy E b (Ce3d U''') = 916.7 eV. [13] The chemical composition was calculated from the XPS data, taking into account atomic sensitivity factors. [29] The original XPS-Calc software, which was successfully tested in our earlier works, [13,[30][31][32] was employed for the deconvolution of experimental spectra into individual components.…”

“…[13] The chemical composition was calculated from the XPS data, taking into account atomic sensitivity factors. [29] The original XPS-Calc software, which was successfully tested in our earlier works, [13,[30][31][32] was employed for the deconvolution of experimental spectra into individual components. The spectral background of the Pt4 f line was subtracted using the Shirley method, and an approximation of the doublets was calculated using Lorentzian and Gaussian functions.…”

“…An even more pronounced effect (converting up to 70 % CO at 25°C, GHSV = 200 000 ml · g À 1 · h À 1 ) was achieved for Pt/CeO 2 catalysts prepared by pulsed laser ablation and activated in oxygen at 450-600°C. [13] The lowtemperature activity was attributed to the formation of oxidised platinum species, such as PtO x clusters and surface solid solutions of platinum ions in ceria.…”