Ceria Reduction via Ce-Sn Bimetallic Bonding

Tin was deposited in the amount of 0.4 and 0.8 nm onto CeO2(111) surface by molecular beam deposition at the temperature of 520 K. The interaction of tin with cerium oxide was studied with use of XPS, UPS and RPES (Resonant Photoelectron Spectroscopy). The strong tin - ceria interaction led to the Ce(4-nx)+Snxn+O22- compound formation. It was accompanied with partial reduction of CeO2 observed as a giant 4f resonance enhancement of Ce3+ species referring to defects in ceria. CeO2 and SnO2 oxides were formed after oxygen treatment at 520 K. The strong Ce - Sn inter- action and Sn - Ce charge transfer that lead to a weakening of cerium - oxygen bond and consequently to the formation of oxygen deficient active sites on the ceria surface can be a key of understanding the high catalytic activity of the SnOx/CeOx catalysts.