Controllable Template-Assisted Electrodeposition of Single- and Multi-Walled Nanotube Arrays for Electrochemical Energy Storage

Abstract

Here we explored a novel ZnO nanorod array template-assisted electrodeposition route to synthesize large-scale single-walled polypyrrole (PPy) nanotube arrays (NTAs) and multi-walled MnO₂/PPy/MnO₂ NTAs. The structures of nanotubes, such as external and inner diameters, wall thicknesses, and lengths, can be well controlled by adjusting the diameters and lengths of ZnO nanorods and deposition time. The synthesized hybrid MnO₂/PPy/MnO₂ triple-walled nanotube arrays (TNTAs) as electrodes showed high supercapacitive perporties, excellent long-term cycling stability, and high energy and power densities. The PPy layers in MnO₂/PPy/MnO₂ TNTAs provide reliable electrical connections to MnO₂ shells and uniquely serve as highly conductive cores to support the redox reactions in the active two-double MnO₂ shells with highly electrolytic accessible surface area. The fabricated multi-walled NTAs allow high efficient utilization of electrode materials with facilitated transports of ions and electrons. The outstanding performance makes MnO₂/PPy/MnO₂ TNTAs promising candidates for supercapacitor electrodes.