Synthesis of ZnO Nanorods/Carbon Nanofiber Composites Using Electrochemical Deposition for Efficient Supercapacitor Electrodes: Control of Nucleation and Growth of ZnO Nanorods

ZnO nanorods can be electrochemically deposited onto carbon nanofiber (CNF) substrates and used for high-performance supercapacitors. The conductive, three-dimensional structure of the CNF web allows for electrodeposition of the ZnO nanorods. Therefore, the properties of the CNF substrate, as well as the deposition conditions, directly relate to the deposition mechanisms of the ZnO nanorods. The ZnO nanorod structure can be modulated by tuning the current density, precursor concentration, and type of applied current. These parameters affect the nucleation and growth mechanisms, resulting in different structures of ZnO nanorods. Applying a pulsed current with a rest time (5 s) during electrodeposition produces denser and narrower ZnO nanorods than those prepared under a constant current. The additional ZnO thin film coating by atomic layer deposition (ALD) on the CNF substrate exhibits a different tendency of the deposition of ZnO nanorods by acting as a seed layer.