Pt/CeO ₂ Catalysts Prepared by Laser Vaporization: Morphology, Structure, Platinum State, and Catalytic Properties in CO Oxidation Reaction

Abstract A new laser vaporization (LAVA) method for the synthesis of CeO 2 nanoparticles, allowed the synthesis of support samples with widely variable surface area and particle sizes. The LAVA‐synthesized CeO 2 nanoparticles exhibit a high degree of crystallinity, characterized by the absence of intracrystalline porosity, but high surface defectiveness and a well‐developed interblock structure. Platinum deposition produces highly dispersed species, including isolated ions (single atoms Pt 2+ ‐SA), ion associates (2D‐PtO x rafts), and oxidized 3D‐PtO x clusters. The catalyst with the largest surface area and the smallest mean particle size of CeO 2 contains platinum mainly in the Pt 2+ ‐SA form, owing to its strongest chemical interaction with the surface of small‐sized nanoparticles. This highly dispersed catalyst does not exhibit low‐temperature activity in CO oxidation, since ignition of the reaction is only observed at T > 150 °C. The catalysts with reduced surface area contain both Pt 2+ ‐SA and 3D‐PtO x clusters located at extended surface defects and along interblock boundaries. The formation of 3D‐PtO x cluster species results in a significant enhancement of the catalytic activity. The most notable catalytic effect is observed for the lowest surface area catalysts, for which CO conversion shows low‐temperature activity with the reaction ignition occurring at sub‐zero temperatures.