Fast synthesis of stable cubic copper nanocages in the aqueous phase

We report here a fast approach to the synthesis of cubic Cu nanocages in higher yield through a wet chemical reductive procedure. The performing reductive reactions from Cu(II) to Cu(0) in the aqueous phase can be finished in just 3 min at the low temperature of 80 degrees C in the presence of sodium oleate (SOA) as a stabilizer. Both transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) results indicate that the resultant cubic Cu cages are aggregates of Cu nanoparticles with 200 nm in edge lengths and the inclusive nanoparticles are about 20 nm in size. According to the inspection of the Cu nanostructure-forming mechanism, we suggest that the reduction intermediate of roughly solid Cu2O cubes formed in this strategy served as a spontaneous shape-controlled template and the cubic structure of the Cu nanostructures was evolved by morphology heredity from them. As we detected, this cubic morphology of Cu aggregates is preserved at varied reaction times, from 3 min to 2 h; it can be presumed that rapidly formed copper cubes are stable in morphology both in solution and as powders in restrained reaction time. Experiments in a longer reaction time of 24 h have also been done by us, and the results showed a trend to form Cu hollow spheres in our system at enough reaction time. Reasonably, the cubic Cu cage is a structure metastable toward hollow spherical materials and it has kinetically controlled growth.