Synthesis and Growth Mechanism of Cu Nanorods via Liquid-Phase Reduction of Cu2O Cubes

Background: The synthesis of one-dimensional Cu nanomaterials, e.g. nanowires or nanorods, normally invovles the use of hard templates, organic additives, or some special conditions, e.g. high vacuum or electric field as discussed in patents. Objective: Herein, we report that, in the absence of any hard template and organic additives, Cu nanorods can be spontaneously formed during low-temperature reduction of Cu2O cubes. Method: The conversion of Cu2O cubes into Cu nanrods is conducted in an alkaline KHB4 aqueous solution at a temperature of 30°C. Results: Nanoparticle-like Cu can be observed on the surface of the cubes in the early stage of reduction. As the reduction reaction proceeds, rod-like Cu appears and some of the cubes can be totally destroyed by the growth of Cu nanorods. Detailed examination of these Cu nanorods reveals that some nanorods are obviously composed of nanoparticles. Moreover, the spontaneous formation of Cu nanorods can be hindered by the addition of ethylenediamine, where Cu cubes made up of Cu nanoparticles can be obtained. Conclusion: Based on these experimental results, a mechanism based on nanoparticle oriented attachment was proposed for the growth of Cu nanorods by liquid-phase reduction of Cu2O cubes.