Morphology-Controlled Synthesis of Co3O4 Nanocubes and Their Catalytic Performance in CO Oxidation

Co3O4 nanocubes that were exclusively terminated with {100} facets of edge size 10 nm were solvothermally fabricated in a mixed solution of ethanol and triethylamine. Analyses of the structural evolution of the intermediates at different intervals during the synthesis, together with an examination of the influences of the cobalt precursor and solvent on the product structure, showed that the formation of Co3O4 nanocubes followed a dissolution-recrystallization mechanism. After calcination at 200 degrees C, the as-synthesized Co3O4 material retained a cubic morphology with the same edge size, but calcination at 400 degrees C resulted in the formation of spherical Co3O4 particles of diameter about 13 nm. The Co3O4 nanocubes exhibited inferior activity in room-temperature CO oxidation compared with Co3O4 nanoparticles ({111} facets), primarily as a result of the exposure of the less-reactive {100} facets, demonstrating the morphology effect of Co3O4 nanomaterials.