Hollow carbon nanocone arrays on carbon fiber cloth as a free-standing electrode for high-performance capacitive deionization

Capacitive deionization (CDI) has been rapidly developed as a competitive desalination technology for obtaining freshwater, wherein the rational design of electrode structures or morphologies plays a crucial role for achieving high-performance CDI process. The most important electrode material is various carbons in forms of 0D nanoparticles or nanocages, 1D nanotubes or nanoscrolls, and 2D nanosheets or nonobelts. Herein, we fabricated highly ordered, highly porous carbon nanocone arrays grown directly on carbon fiber cloth (CNCC) for using as an integrated, binder-free CDI electrode. The CNCC is characteristic of a hollow and end-open structure, graphene-like ultrathin cone walls, abundant pores on the walls, and a large electrochemical active surface area, endowing it with excellent electrical conductivity and unimpeded ion transport pathways. A symmetric CDI desalination cell, which was constructed with a pair of CNCC electrodes, delivered a high electrosorption capacity of 25.9 mg/g in 250 mg/L NaCl solution at 1.2 V, fast adsorption rate (0.43 mg/g min⁻¹), and satisfactory cycling stability (80 % capacity retention after 3 days). This research sheds light on the carbon-nanocone based materials for their preparation and promising applications in CDI and energy storage.