STM study of the growth of cerium oxide nanoparticles on Au(1Â 1Â 1)

The morphology and structure of nanosized ceria particles prepared by several in vacuo deposition methods on a Au(1 1 1) template were investigated by scanning tunneling microscopy. Cerium metal nanoparticles on gold have limited reactivity toward molecular oxygen and NO2, due to the formation of Ce-Au alloys, and their oxidation leads to formation of non-uniform substoichiometric three-dimensional (3D) oxide particles. Cerium metal deposition onto condensed multilayers of water or NO2 generates fully oxidized but poorly ordered ceria particles after annealing. Ultra-thin flat and ordered ceria nanoislands were prepared by deposition of cerium metal on the gold surface at elevated temperatures under an oxygen background pressure. Atomically resolved images show an oxygen-terminated surface of CeO2(1 1 1) with oxygen vacancies.