We now focus on the evolution of atomic charges in Pt atoms of the considered systems upon oxidation. The atomic charges (calculated by means of Bader's atoms in molecules approach) of the Pt atoms of the most stable oxidation states of each system are shown on Figure . All considered stoichiometries follow similar trends in their charge distribution. As expected, as the system increases its oxidation states, so does the average charge. It is also notable that the effect of the oxygen atoms in the ceria surface on the charge of the platinum atoms is slightly lower than that of the oxygen atoms adsorbed in the platinum cluster. This is visible when comparing the ceria-supported Pt3O5 structure to the free-standing counterpart. Despite the contact to atoms from the ceria surface, the Pt atoms of the Pt3O5 particle appear to be more oxidized for the free-standing case. Thus, although the CeO2(111) surface has an oxidizing effect on the particles and allows to complete certain stable structural motifs, bonds formed with O atoms from the ceria lattice are weaker and less oxidizing than those with O atoms directly on the PtOx particles.