Cost-effective synthesis route for ultra-high purity of Ti3AlC2 MAX phase with enhanced performance of Ti3C2Tx MXene and MXene/NiO composite for supercapacitor application

Abstract

MXene, an emerging material with versatile properties, holds immense promise for supercapacitor applications. However, transitioning from laboratory-scale synthesis to commercial viability faces significant challenges, primarily due to the prohibitively high cost, small lifespan, and self-stacking nature. Prior attempts to lower the cost burden by employing TiO2 as impurities such as TiC, TiAl, and Ti2AlC have hindered a precursor rather than Ti/TiC expensive materials. Herein, a synthesis method was presented to prepare an ultra-high pure Ti3AlC2 MAX phase using an optimized molar ratio of precursors (TiO2: Al: C), calcination process, and HCl washing. The obtained material was subsequently transformed into pure Ti3C2Tx MXene by a mild etching process that helps to sustain a long lifespan. Further, to address the restacking issue and low performance of Ti3C2Tx for supercapacitor applications, a composite of MXene/NiO (MX/NiO) was synthesized through bath sonication. MXene exhibits a specific capacitance of 358.5 F g−1, while MX/NiO composite achieves 892 F g−1 at 1 A g−1 current density within a potential window of −0.6 – 0.4 V with 2 M H2SO4 electrolyte. Further, in 6 M KOH electrolyte, Ti3C2Tx and MX/NiO-based symmetric supercapacitors show 171 and 461 F g−1 specific capacitance at 1 A g−1 current density. The DFT-based theoretical capacitance analysis of MAX phase, MXene, and MX/NiO composite supports electrochemical results. By addressing the limitations of previous approaches, this methodology can bridge the gap between laboratory research and large-scale commercial production of MXene, thus unlocking its full potential for supercapacitor applications.