<div> <div>DFT calculations were carried out using the CP2K and Quantum ESPRESSO packages to study the structural, electronic, and catalytic properties of platinum nanoparticles supported on ceria surfaces. The models included Pt nanoparticles of different sizes on CeO₂ surfaces. The DFT+U approach was used to describe Ce 4f electrons, and 4f-in-core pseudopotentials were employed to model Ce³⁺ species. Adsorption energies, XPS binding energies, and reaction energies were computed to analyze the interaction of Pt with the ceria support and adsorbate (CO), providing insights into the size-dependent electronic behavior and catalytic activity of Pt species.</div> </div>