Electrostatically induced reconstruction of the 3D nitrogen-doped Ti3C2Tx electrode and its excellent desalination performance for hybrid capacitive deionization

Abstract

Capacitive deionization is a promising solution for freshwater production with Ti₃C₂T_x emerging as a momentous electrode material. Here, highly porous 3D nitrogen-doped Ti₃C₂T_x (3D-N-Ti₃C₂T_x) is developed by using electropositive melamine to electrostatically induce electronegative Ti₃C₂T_x nanosheets to be reconstructed to alleviate the severe stacking problem of Ti₃C₂T_x layers. 3D-N-Ti₃C₂T_x has a large specific surface area (129.48 m² g⁻¹) and pore volume (0.372 cm³ g⁻¹), exposing numerous ion adsorption sites. Also, 3D-N-Ti₃C₂T_x achieves nitrogen doping, which greatly improves the hydrophilicity and electrical conductivity. With the combined advantages of a three-dimensional structure and nitrogen doping, 3D-N-Ti₃C₂T_x achieves a specific capacitance of 101.9 F g⁻¹ in 1 mol L⁻¹ NaCl solution and demonstrates fantastic desalination performance with a high desalination capacity of 31.51 mg g⁻¹, surpassing those of the majority of reported Ti₃C₂T_x electrodes, and outstanding desalination cycling stability in 500 mg L⁻¹ NaCl solution at 1.2 V. This work significantly contributes to the advancement of Ti₃C₂T_x electrode material in CDI.