Morphology Control of Cu Crystals on Modified Conjugated Polymer Surfaces

We report the fabrication of a series of micro-/nanostructured copper particles with various sizes, structures, and morphologies on polyaniline (PANI) membranes via an electrochemical deposition method. Different dopants applied in PANI membranes can lead to the production of Cu particles with various morphologies, including cubic, dendritic, textured spherical, and octahedral structures. On a citric acid (CA)-doped PANI membrane, the deposition of aggregated Cu nanoparticles is observed at an early stage, and these aggregated nanoparticles serve as the template to form larger Cu microspheres through a fill-in process. For a camphorsulfonic acid (CSA)-doped PANI membrane, a morphological transition of Cu metal from octahedral to dendritic structure is observed as the reaction time is prolonged, suggesting a branching growth mechanism. In addition to this unique control of the growth mechanism by varying the dopant, we find certain additives, such as citrate, can alter the growth of copper particles into a two-stage growth process, which results in the formation of copper microspheres decorated by nanowires and jellyfish-like structures for both CSA and CA-doped membranes. To the best of our knowledge, this is the first time where the electrochemical deposition of micro-/nanostructured copper using a two electrode setup with tunability in size, structure, and morphology has been demonstrated. These results offer valuable insights in understanding the underpinning growth mechanisms, imply an efficient method to control size and morphology, and enable designed synthesis of complex copper micro-/nanoparticles.