Controllable Design and Preparation of Hollow Carbon-Based Nanotubes for Asymmetric Supercapacitors and Capacitive Deionization.

Abstract

Carbon-based materials are important desirable materials in areas such as supercapacitors and capacitive deionization. However, traditional commercial materials are heterogeneous and prone to agglomeration in nanoscale and have structural limitation of electrochemical and desalination performance due to poor transport channels and low capacitance of prepared electrodes. Here, we introduce the facile strategy for controllable preparation of two types of hollow carbon-based nanotubes (HCTs) with amorphous mesoporous structures, which are synthesized by employing a MnO2 linear template method and calcination of polymer precursors. The porous N-doped HCT (NHCT) shows a specific capacitance of 412.6 F g-1 (1 A g-1), with 77.3% rate capability (20 A g-1). The fabricated asymmetric MnO2//NHCT supercapacitor displays the energy density of 55.8 Wh kg-1 at a power density of 803.9 W kg-1. Furthermore, two typical MnO2//HCT and MnO2//NHCT devices both show the selective desalination performance of sulfate, and the MnO2//NHCT device possesses a high deionization value of 11.37 mg g-1 (500 mg L-1 Na2SO4). These fabricated hollow carbon-based architectures with functional characteristics promise potential applications in energy and environmental related fields.