Copper Nanostructures Controlled Reduction Method

Metal nanomaterials have extensive prospects in the field of catalysis, optics, electronics, biology, etc. Thus increasing attention has been drawn into the area. In this work, solution-based chemical methods have been developed to synthesize the copper nanoparticles with expected size as well as size distribution. The influence of reaction parameters were investigated systemically. Different effects of three kinds of typical capping agents were studied respectively. Moreover, some copper nanoparticles with interesting structures and morphologies, such as hollow cubes and spherical aggregates, were obtained. The possible mechanisms for the formations of these nanostructures were proposed. The main results are summarized as follow:Sub-10 nm and narrow size distributed copper nanoparticles were synthesized with CTAB as capping agent and N₂H₄·H₂O as reductant. It was found that the size and size distribution of nanoparticles were strongly depended on the reaction temperature. Enlarged nanoparticles with a broadened size distribution can be prepared at a rising temperature. FTIR results show that CTAB molecules form a bilayer structure around the copper nanoparticles in which the inner layer is bound to the copper surface via the surfactant headgroups, instead of a micelle structure.At the presence of SDS spherical aggregates assembled by 10 nm nanoparticles were obtained. The formation mechanism relates to the competition between interparticle electrostatic interactions and steric effect. The size of the aggregate and the density of nanoparticles aggregated in it can be controlled by the addition of ammonia. In the absence of ammonia, well-defined spherical nanoparticles without aggregating can be obtained. Moreover, small-sized copper cubic nanoparticles were also obtained in a higher reactant concentration comparing with that in others' experiment.Copper nanocages with hollow interior were prepared. The formation process can be explained by the combination of both corrosion and Ostwald ripening.