Effect of 3.7 at% F doping on the atomic structure and reducibility of CeO2(111) surface: A first principles calculation

Density functional theory calculations was conducted to clarify effect of fluorination on the reducibility of CeO2 polishing powder. The atomic structure and O vacancy formation energy of F-doped CeO2(111) surface were systematically calculated, and electronic structure was also analyzed to understand the calculation results. It showed that the CeO1.963(111) surface needs absorb 7.853 eV to be reduced further, so it is difficult to generate the second O vacancy (V2). After fluorination, the first O vacancy (V1) in CeO1.926F0.037(111) surface caused adjacent atoms to move significantly, and O vacancy formation energy decreased to 2.913 eV, which promoted the formation of V2. Moreover, electronic structure calculation also showed that the interaction between O2p and Ce4f5d orbits was enhanced in reduced CeO1.963(111) surface, which hindered the formation of V2. The F2p orbit in CeO1.926F0.037(111) surface moved towards the low energy level, V1 made the reduced surface stable and promoted the formation of V2.