A Strategy for Synthesis of Carbon Nitride Induced Chemically Doped 2D MXene for High-Performance Supercapacitor Electrodes

作者：Yoon Yeoheung; Lee Minhe; Kim Seong Ku; Bae Garam; Song Wooseok; Myung Sung; Lim Jongsun; Lee Sun Sook; Zyung Taehyoung; An Ki Seok

来源：Advanced Energy Materials, 2018, 8(15): 1703173.

DOI：10.1002/aenm.201703173

<jats:title>Abstract</jats:title><jats:p>A step‐by‐step strategy is reported for improving capacitance of supercapacitor electrodes by synthesizing nitrogen‐doped 2D Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> induced by polymeric carbon nitride (p‐C<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub>), which simultaneously acts as a nitrogen source and intercalant. The NH<jats:sub>2</jats:sub>CN (cyanamide) can form p‐C<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> on the surface of Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> nanosheets by a condensation reaction at 500–700 °C. The p‐C<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> and Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> complexes are then heat‐treated to obtain nitrogen‐doped Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> nanosheets. The triazine‐based p‐C<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> decomposes above 700 °C; thus, the nitrogen species can be surely doped into the internal carbon layer and/or defect site of Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> nanosheets at 900 °C. The extended interlayer distance and <jats:italic>c</jats:italic>‐lattice parameters (<jats:italic>c</jats:italic>‐LPs of 28.66 Å) of Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> prove that the p‐C<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> grown between layers delaminate the nanosheets of Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> during the doping process. Moreover, 15.48% nitrogen doping in Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> improves the electrochemical performance and energy storage ability. Due to the synergetic effect of delaminated structures and heteroatom compositions, N‐doped Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic> shows excellent characteristics as an electrochemical capacitor electrode, such as perfectly rectangular cyclic voltammetry results (CVs, <jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.9999), high capacitance (327 F g<jats:sup>−1</jats:sup> at 1 A g<jats:sup>−1</jats:sup>, increased by ≈140% over pristine‐Ti<jats:sub>2</jats:sub>CT<jats:italic><jats:sub>x</jats:sub></jats:italic>), and stable long cyclic performance (96.2% capacitance retention after 5000 cycles) at high current density (5 A g<jats:sup>−1</jats:sup>).</jats:p>

• 出版日期2018-5-25