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

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.