Fabrication of TiO2/CNTs composite electrode with improved performance in capacitive deionization

Abstract

Many studies have shown that capacitance deionization (CDI) has great potential in salt-water treatment, one of the issues of great concern in many countries, especially Vietnam. The electrode material in CDI is one of the essential factors contributing to the desalination efficiency of this technology, so it is of research interest. In this study, TiO₂ and TiO₂/carbon nanotubes (CNTs) were synthesized from the sol-gel process and utilized as an electrode for desalination. The composite materials were intensively characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and thermal analysis. The electrochemical properties were investigated using electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge. The fabricated TiO₂/CNTs nanocomposite electrode consisting of 1% CNTs (electrode T1) exhibited remarkable capacitance, conductivity, and durability; thus, it was employed as an electrode for desalination. With this electrode T1, the maximum salt adsorption capacity of 17.5 mg g⁻¹, together with the highest charge efficiency of 90%, was achieved. Therefore, TiO₂/CNTs can be considered a suitable electrode candidate for CDI technology.