CO oxidation and NO reduction by CO over Sn4+ doped CeO2 catalysts: Determination of active sites as well as commonness and differences

Sn doping sites in CeO2 can greatly affect its electronic structures. However, the identification of adsorption/active sites, their effects on CO oxidation and NO reduction by CO, and the commonness and differences between the two reactions have never been addressed. Herein, Sn4+ is selectively doped into nano-rod and nano-cubic CeO2 by hydrothermal methods. It is found that the Ce10Sn1Ox catalysts exhibit greatly promotional effects on both the two reactions, which benefits from the formation of more oxygen vacancies (OVs), stronger redox ability that can enhance the mobility of lattice oxygen, lower formation energies of OVs, and weaker alkalinity that can increase the desorption of product CO2. Experiments and DFT calculations show that they share the same adsorption/active site, i.e., Sn2+−Ov−Ce3+, in the two reactions. Meanwhile, the CO oxidation half-reaction has obvious dependence on the active [O] species derived from the dissociation of NO species during NO reduction by CO. [Display omitted] •Ce10Sn1Ox catalysts exhibit greatly promotional effects on both the two reactions.•Doping of Sn4+ into CeO2 rearranges the electronic structure of Sn2+−Ov−Ce3+ site.•They share the same adsorption/active site, i.e., Sn2+−Ov−Ce3+, in the two reactions.•The structure of CeO2 itself is proved to be well preserved after the doping of Sn4+.