Hollow Mesoporous Co₃ O₄ -CeO₂ Composite Nanotubes with Open Ends for Efficient Catalytic CO Oxidation

Catalytic performance is heavily dependent on how the structures of nanomaterials are designed. Co₃ O₄ -CeO₂ composite nanotubes with open ends and mesoporous structures were fabricated through a facile and environmentally friendly reaction. The mesoporous Co₃ O₄ nanotubes were synthesized by the calcination of cobalt-aspartic acid (Co-Asp) nanowires and coated with a CeO₂ shell. The composite nanotubes were characterized by SEM, TEM, XRD, and X-ray photoelectron spectroscopy. The composite materials comprise a combination of Co₃ O₄ nanotubes and CeO₂ nanoparticles with a hollow and mesoporous bimetallic oxide structure. The large BET surface area led to a higher degree of accessible active sites compared with other Co₃ O₄ -CeO₂ composite nanomaterials with other structures. The resulting Co₃ O₄ -CeO₂ -26.3 wt % composite nanotubes, with a CeO₂ content of approximately 26.3 wt %, achieved 100 % CO conversion at 145 °C. Additionally, the synergistic effect between the two metal oxides comprising the Co₃ O₄ -CeO₂ composite nanotubes was demonstrated by the enhanced catalytic activity compared with pure Co₃ O₄ nanotubes and CeO₂ nanoparticles.