Shape-selective separation of copper nanowires and copper-based nanoparticles by a ligand exchange strategy

Copper nanowires (Cu NWs) have been regarded as one of the most potential materials in the field of optoelectronics. However, the performance of Cu NWs based devices are directly affected by the purity of the Cu NWs, which mainly depends on the containing copper nanoparticle (Cu NPs). Here, we developed a novel shape-selective approach by a reversible ligand exchange process that simultaneously satisfies the high efficiency, high selectivity, and less deterioration of the target Cu NWs. Due to the difference in ligand exchange rates between Cu NWs and Cu NPs, the Cu NWs kept be hydrophobic and spontaneously floated up to the interface between the aqueous solution of organic additive and air, while the Cu NPs turned to be hydrophilic and dispersed evenly in the solution. Using sodium 3-mercaptopropanesulphonate as the ligand exchange reagent, the Cu NWs and Cu NPs can be separated efficiently under the optimal operation conditions. The organic additive can be screened according to the surface tension of the solution and easily available. Besides, this strategy is applicable to effectively separate Cu NWs from Cu@Ag NPs and Ni@Cu NPs. This method based on the ligand exchange is expected to promote the shape-selective separation of nanomaterials.