More than oxygen vacancies: a collective crystal-plane effect of CeO2 in gas-phase selective oxidation of benzyl alcohol

Abstract

The morphology and crystal-plane effects of CeO₂ materials (nanorods, octahedra, cubes, and particles) in gas-phase selective oxidation of benzyl alcohol were investigated. HRTEM, XPS and TPR analyses showed that CeO₂ nanorods enclosed by {110} and {100} facets are richer in oxygen vacancies than nanocubes, octahedra and nanoparticles. Their catalytic activity towards the gas-phase selective oxidation of benzyl alcohol, however, followed the order nanorods > nanoparticles ≈ nano-octahedra > nanocubes, which was not fully consistent with the content of oxygen vacancies. Further characterization together with density functional theory (DFT) calculations revealed that the exposed crystal planes can not only determine the content of oxygen vacancies, but also influence the ability to abstract H, adsorb O₂ and remove water. The combination of all these factors leads to a collective crystal-plane effect of ceria, and these results can help deepen our understanding of ceria surface chemistry.