Figure 2. Capacity of stepped CeO₂(111) surface to accommodate Pt²⁺.

(a) Amount of Pt²⁺ stabilized on CeO₂(111) substrates with different density of steps for 0.18 ML (blue symbols) and 0.06 ML (black symbols) of deposited platinum. Pt not stabilized in the form of Pt²⁺ remains metallic. Lines represent guides to the eyes. Blue line is a linear fit of 0.18 ML Pt data. Black line represents the maximum achievable amount of Pt²⁺ in the case of 100% oxidation of Pt for 0.06 ML of deposited Pt. (b) Reduction of the ceria surface accompanying the stabilization of Pt²⁺ ions determined by resonant PES expressed as a coverage of the surface by Ce³⁺ ions. Lines represent guides to the eyes from a and indicate the Pt²⁺ concentration. The Ce³⁺ concentration is lower or equal to the Pt²⁺ concentration on all samples.