Synthesis of Co3O4 nanotubes and their catalytic applications in CO oxidation

• Oxidizing Co nanowires yielded Co3O4 nanotubes with the inner diameter of 8 nm.
• The formation of the tubular structure followed a nanoscale Kirkendall effect.
• Hydrogen reduction of the Co3O4 nanotubes occurred at a much lower temperature.
• The Co3O4 nanotubes had a better activity in CO oxidation at room temperature.

Co3O4 nanotubes with the inner of about 8 nm and the length of 200–500 nm were synthesized by oxidizing Co nanowires. Analyses on the structural evolution of the intermediates at different intervals identified that the formation of Co3O4 nanotubes followed a nanoscale Kirkendall effect. The outward diffusion of cobalt species was faster than the inward diffusion of oxygen species, resulting in the formation of nanovoids at the initial stage and subsequently the tubular structure. The Co3O4 nanotubes showed a higher activity and stability than the spherical nanoparticles in CO oxidation, primarily due of the facile redox feature.

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