Simultaneous Intercalation and Oxidant-Free Polymerization of Pyrrole Between 2D Titanium Carbide (MXene) for High Performance Pseudocapacitive Electrodes

Electrochemically active organic materials which offer pseudocapacitve characteristics are attractive for energy storage applications because they are economical, environmentally benign, lightweight, and their functionalities can be tuned to achieve the required electrochemical properties. 1 Despite aforementioned advantages, they tend to degrade upon cycling mainly because of their poor conductivity. One option to improve the cycling and the overall electrochemical performance of the pseudocapacitve organic materials is to deposit/graft them onto conductive carbon particles. 2 Two-dimensional carbides and carbonitirides called MXenes, which generally offer metallic conductivity, may become a suitable option to replace carbon in pseudocapacitve electrodes to improve the electrochemical performance of the organic materials. 3,4 Here, we report a facile approach to simultaneously align and intercalate heterocyclic organic molecule pyrrole between the Ti 3 C 2 T x MXene layers. On contrary to the conventional approaches, pyrrole monomer was polymerized without addition of any oxidant when mixed with the Ti 3 C 2 T x colloidal solution, which was confirmed by various spectroscopic techniques. When the optimized composition was tested as a pseudocapacitive electrode, it exhibited high volumetric and gravimetric capacitances of 1000 F/cm 3 and 416 F/g, respectively, at 5 mV/s. Most important, excellent capacitance retention of 92% was observed after 25,000 cycles at 100 mV/s. 1. M. Boota et al., Adv. Mater. (2015). DOI (10.1002/adma.201504705) 2. M. Boota et al., ChemSusChem , 8 , 3576–3581 (2015) 3. M. R. Lukatskaya et al., Science. , 341 , 1502–1505 (2013) 4. M. Ghidiu, M. R. Lukatskaya, M.-Q. Zhao, Y. Gogotsi, and M. W. Barsoum, Nature , 516 , 78–81 (2014)