Three-dimensional carambola-like MXene/polypyrrole composite produced by one-step co-electrodeposition method for electrochemical energy storage

Two-dimensional (2D) MXenes have been extensively investigated for electrochemical energy storage because of their excellent electronic properties. In this work, a facile and effective method was developed to fabricate MXene/polypyrrole (MXene/PPy) composite film electrodes via one-step co-electrodeposition. In this process, 2D Ti3C2Tx-MXene nanosheets acted as a core polymer because of the functional groups, such as -F, -OH, or -O, on their surface, and pyrrole monomer radical cations (Py center dot(+)) would gradually polymerize on the surface and layer space of the 2D MXene nanosheets to form three-dimensional (3D) carambola-like MXene/PPy composite films. The 3D structure composite facilitated electron transfer and ionic diffusion, so the MXene/PPy composite film electrodes exhibited an outstanding electrochemical performance with a high gravimetric capacitance of 416 F g(-1) at a current density of 0.5 A g(-1) in a three-electrode system. The as-fabricated symmetric supercapacitors of ITO-glasses coated with MXene/PPy composite films also exhibited a high specific capacitance (184 F g(-1) at a scan rate of 10 mV s(-1)), excellent reliability and good cycling stability (approximately 86.4% retention after 5000 cycles, at 5 A g(-1)). (C) 2019 Elsevier Ltd. All rights reserved.