fig1

Figure 1. (A) HAADF-STEM image of the Pt₁/FeO_x catalyst where the Pt SAs occupy the positions of the Fe atoms; (B) Comparison of TOFs; (C) The proposed reaction pathways for CO oxidation on the Pt₁/FeO_x catalyst^[42]. Copyright 2013, Springer Nature; (D) The changes of surface free energy and specific activity with metal particle size^[43]. Copyright 2013, American Chemical Society; (E) The geometric and electronic structures of particles of several different sizes: SAs, clusters, and NPs^[44]. Copyright 2018, American Chemical Society; (F) Schematic illustration of dispersion states of metal species on SACs, DACs and SA-cluster/NP catalysts^[48]. Copyright 2022, American Chemical Society; (G) Schematic illustration of the controlled synthesis strategy for SACs^[53]. Copyright 2020, American Chemical Society. HAADF-STEM: High angle annular dark field-scanning transmission electron microscopy; SA: single atom; TOF: turnover frequency; NP: nanoparticle; SAC: single-atom catalyst; DAC: dual-atom catalyst.