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

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 (Pt) to Pt single atoms (Pt) conversion on CeO. Owing to the excellent tunability of input laser energy, the proportion of Pt versus total Pt on CeO can be precisely controlled from 0 to 100% by setting different laser powers and irradiation times. The obtained PtPt/CeO catalyst with approximately 19% Pt and 81% Pt exhibited much-enhanced CO oxidation activity than Pt/CeO, Pt/CeO, and other PtPt/CeO catalysts. Density functional theory (DFT) calculations showed that Pt was the major active center for CO oxidation, while Pt changed the chemical potential of lattice oxygen on CeO, 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.