Defect engineered Ti3C2Tx MXene electrodes by phosphorus doping with enhanced kinetics for supercapacitors

Abstract

Supercapacitors (SCs) have attracted increasing attention due to high power density, rapid charge/discharge, excellent cyclic stability, and withstands adverse environments. Two-dimensional (2D) Ti₃C₂T_x MXene is considered as a promising electrode material for electrochemical energy storage. However, undesirable low specific capacitance issues limit its practical applications. Herein, a facile heteroatom doping strategy is proposed to construct defect-rich Ti₃C₂T_x MXene with abundant active cites. Hence, P-doped Ti₃C₂T_x MXene was synthesized by a simple annealing method. The prepared P-doped Ti₃C₂T_x was used as the electrode material of SC, and it was found that the P-doped Ti₃C₂T_x exhibits enhanced electrochemical performance compare to the pristine Ti₃C₂T_x MXene, the P-doped Ti₃C₂T_x electrode could deliver a high specific capacity of 31.11 mA h g⁻¹ at 1 A g⁻¹ in 1 M KOH electrolyte. Furthermore, a P-doped Ti₃C₂T_x based symmetric SC device is fabricated and displays excellent energy density of 8.2 Wh L⁻¹ at a power density of 303.4 W L⁻¹. This study provides a straightforward strategy to design and construct MXene-based electrode materials with enlarged layer spacing structure for high-performance K⁺ storage and even in other metal ion storages.