High supercapacitance performance of nitrogen-doped Ti3C2Tx prepared by molten salt thermal treatment

Ti3C2Tx with -F surface terminations were treated in LiCl-KCl-Li3N molten salt at atmospheric pressure to introduce N and simultaneously remove -F surface terminations, in which LiCl-KCl salt was used as the solvent and Li3N as the nitrogen source. By optimizing the mass ratio of Li3N:Ti3C2Tx to be 1:2, N-doped Ti3C2Tx (N-Ti3C2Tx-0.5) was obtained with 19.6 at% nitrogen element and 0.69 at% -F surface terminations, leading to the substitution of C by N atoms and the D-spacing expansion from 0.96 to 1.15 nm. Owing to its good electrical conductivity and high electrochemical activity area, the N-TTi3C2Tx- 0.5 electrode showed a higher specific capacitance (332 F g(-1) at 0.5 A g(-1) in 1 M H2SO4 solution), good rate performance (83.1% at 20 A g(-1)), and excellent capacitance retention (87.5% after 10 0 0 0 charging-discharging cycles). This paves a new way to achieve MXene electrodes with high specific capacitances and excellent retention performance. (c) 2021 Elsevier Ltd. All rights reserved.