Controllable Conversion of Platinum Nanoparticles to Single Atoms in Pt/CeO₂ by Laser Ablation for Efficient CO Oxidation

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Downsizing metal nanoparticles to single atoms (monoatomization of nanoparticles) has been actively pursued to maximize the metal utilization of noble-metal-based catalysts and regenerate the activity of agglomerated metal catalysts. However, precise control of monoatomization to optimize the catalytic performance remains a great challenge. Herein, we developed a laser ablation strategy to achieve the accurate regulation of Pt nanoparticles (PtNP) to Pt single atoms (Pt₁) conversion on CeO₂. Owing to the excellent tunability of input laser energy, the proportion of Pt₁ versus total Pt on CeO₂ can be precisely controlled from 0 to 100% by setting different laser powers and irradiation times. The obtained Pt₁PtNP/CeO₂ catalyst with approximately 19% Pt₁ and 81% PtNP exhibited much-enhanced CO oxidation activity than Pt₁/CeO₂, PtNP/CeO₂, and other Pt₁PtNP/CeO₂ catalysts. Density functional theory (DFT) calculations showed that PtNP was the major active center for CO oxidation, while Pt₁ changed the chemical potential of lattice oxygen on CeO₂, which decreased the energy barrier required for CO oxidation by lattice oxygen and resulted in an overall performance improvement. This work provides a reliable strategy to redisperse metal nanoparticles for designing catalysts with various single-atom/nanoparticle ratios from a top-down path and valuable insights into understanding the synergistic effect of nano-single-atom catalysts.