Baize-like CeO₂ and NiO/CeO₂ nanorod catalysts prepared by dealloying for CO oxidation

Baize-like monolithic CeO₂ and NiO/CeO₂ nanorod catalysts were prepared by combined dealloying and calcination and the catalytic activities were evaluated using CO catalytic oxidation. The CeO₂ catalysts were composed of nanorods and exhibited a three-dimensional supporting structure with pores. After introduction of NiO, dispersed NiO nanosheets and nanoparticles were supported on the surface of CeO₂ nanorods and they were not well-crystallined due to CeO₂ inhibiting the NiO crystallization. The Raman and x-ray photoelectron spectroscopy analyses revealed that the introduction of NiO species into CeO₂ generated more coordinate unsaturated Ni atoms, oxygen vacancies, defects and active sites for CO catalytic reactions. The reaction activation energy of NiO/CeO₂ nanorod catalyst prepared from the Al₈₃Ce₁₀Ni₇ precursor alloy was just 31.2 kJ mol^-1 and the CO conversion can reach up to 97% at 240 °C, which was superior to that of pure CeO₂ and nanoporous NiO. The enhanced catalytic activity of baize-like NiO/CeO₂ nanorods can be attributed to the strong synergistic effects between finely dispersed NiO species and surface oxygen vacancies in CeO₂ nanorods.