Engineering the NiO/CeO2 interface to enhance the catalytic performance for CO oxidation

Abstract

In this work, NiO/CeO₂ catalysts were synthesized with tunable CeO₂ crystal facets ({110}, {111} and {100} facets) to study the crystal-plane effects on the catalytic properties. Kinetic studies of CO oxidation showed that NiO/CeO₂ {110} had the lowest activation energy. Furthermore, the obtained samples were characterized by means of TEM, XRD, Raman, N₂-physisorption, UV-Vis DRS, XPS, H₂-TPR and in situ DRIFTS technologies. The results demonstrated that the geometric and electronic structures of the nickel species were dependent on the NiO/CeO₂ interfaces, which had an influence on the synergetic interaction of absorbed CO and active oxygen species, and then the generation of the formate intermediate played an important role in the catalytic performance. The possible interface structures of nickel species on the CeO₂ {110}, {111} and {100} surface were proposed through the incorporation model, suggesting that the advantageous NiO/CeO₂ {110} interface facilitated CO adsorption/activation and active oxygen species formation, leading to the best catalytic performance.