Wooseok Song, Minhe Lee, Taehyoung Zyung, Sun Sook Lee, Yeoheung Yoon, Ki-Seok An, Seong Ku Kim, Sung Myung, Garam Bae, Jongsun Lim
A step-by-step strategy is reported for improving capacitance of supercapacitor electrodes by synthesizing nitrogen-doped 2D Ti2CTx induced by polymeric carbon nitride (p-C3N4), which simultaneously acts as a nitrogen source and intercalant. The NH2CN (cyanamide) can form p-C3N4 on the surface of Ti2CTx nanosheets by a condensation reaction at 500–700 °C. The p-C3N4 and Ti2CTx complexes are then heat-treated to obtain nitrogen-doped Ti2CTx nanosheets. The triazine-based p-C3N4 decomposes above 700 °C; thus, the nitrogen species can be surely doped into the internal carbon layer and/or defect site of Ti2CTx nanosheets at 900 °C. The extended interlayer distance and c-lattice parameters (c-LPs of 28.66 Å) of Ti2CTx prove that the p-C3N4 grown between layers delaminate the nanosheets of Ti2CTx during the doping process. Moreover, 15.48% nitrogen doping in Ti2CTx improves the electrochemical performance and energy storage ability. Due to the synergetic effect of delaminated structures and heteroatom compositions, N-doped Ti2CTx shows excellent characteristics as an electrochemical capacitor electrode, such as perfectly rectangular cyclic voltammetry results (CVs, R2 = 0.9999), high capacitance (327 F g−1 at 1 A g−1, increased by ≈140% over pristine-Ti2CTx), and stable long cyclic performance (96.2% capacitance retention after 5000 cycles) at high current density (5 A g−1).
Carbon nitride (p-C3N4) induced chemically nitrogen doped 2D Ti2CTx for supercapacitor electrodes is reported. The synthesized 900N-Ti2CTx exhibits a high N atom concentration of 15.48% via thermal decomposition process of p-C3N4, and significant improvements in supercapacitor performance parameters, such as capacitance, rate, and cyclic life, are achieved due to the delaminated structures, high nitrogen content, and improved electrical conductivity.