Strain-Induced Oxygen Vacancies in Monolayered CeO2(111) Islands Grown on Pt(111)

Ceria films grown on noble metal substrates have been widely studied as inverse model catalysts due to their high performance in various catalytic processes. Here, the oxygen vacancies formed in monolayered ceria islands on Pt(111) are explored by scanning tunneling microscopy and low-energy electron diffraction. The grown ceria forms (2 x 2) and (5 x 5) supercells to release the lattice strain due to their imperfect 3:4 lattice match with the underlying Pt(111) substrate lattice. The oxygen vacancies initially develop at the specific sites in the mismatched domains and subsequently grow into regular (3 x 3) supercells to link the mismatched domains.