A novel electrode hybrid of N–Ti3C2Tx/C/CuS fabricated using ZIF-67 as an intermediate derivation for superhigh electrochemical properties of supercapacitors

Abstract

The development of high-performance electrode materials with a far-from-enough energy density has still been crucial for the real applications of supercapacitor technology. In this paper, the N-doped and derivatized-carbon-intercalated Ti3C2Tx, abbreviated as N–Ti3C2Tx/C, was firstly fabricated using ZIF-67 as an intermediate precursor. Then N–Ti3C2Tx/C/CuS was prepared by further intercalation with CuS nanoparticles through a room-temperature-in-situ-reaction route. The doped pyridine N and pyrrolic N, together with derivatized carbon, optimized the surface charge distribution of Ti3C2Tx with increased active sites. In addition, CuS nanoparticles were observed distributed on the surface and between layers of single/multi-layered two-dimensional N–Ti3C2Tx/C nanosheets, forming a heterogeneous three-dimensional structure. Therefore, the specific capacitance of the N–Ti3C2Tx/C/CuS composite at a current density of 1 A g−1 reached 1205.8 F g−1, about 5 times that of N–Ti3C2Tx/C and 2 times of CuS, also much higher than other composite reported in the literature. The energy density and power density of N–Ti3C2Tx/C/CuS, as a symmetric supercapacitor electrode, are 77.22 Wh·kg−1 and 649.54 W kg−1, respectively. More importantly, N–Ti3C2Tx/C/CuS has an excellent stability after 3000 cycles, surpassing that of similar electrode materials reported in literature. This study opens a new direction for enhancing the energy density of supercapacitors with modified electrode materials through a MOF-mediated strategy.

Keywords

• Ti3C2Tx
• CuS
• ZIF-67
• Supercapacitor
• Specific capacitance
• Energy density