Construct mesoporous MXenes by thermal shock induced pore engineering for high performance supercapacitor

Abstract

As one of the latest additions to two dimensional (2D) family, transition metal carbides, carbonitrides and nitrides (MXenes) suffer from sluggish ion transport kinetics and insufficient active site utilization, resulted from self-restacking for application in electrochemical energy storage. Construction of in-plane pores will restrain restacking and avoid redundant macropores, however, it remains an obstacle due to MXenes’ unique etching preparation process and vulnerable resistance to oxidation. Herein, by taking advantage of the confined interlayer spaces of Ti3C2Tx MXenes, combining with rapid annealing process, a novel thermal shock induced pore engineering strategy was proposed to successfully construct in-plane mesoporous MXene nanosheets, simultaneously minimizing the oxidation and preserving their hydrophilicity. Consequently, the optimized porous electrode structures significantly provide substantial redox-active sites and accelerate ion transportation, leading to a remarkable specific capacitance (494.8 F g-1 at 5 mV s–1), an unparalleled rate capability (91.5% capacitance retention with a low mass loading, 59.7% with a high mass loading of 7.89 mg cm-2 at 2 000 mV s-1) and robust cycling stability. This work sheds new light on the construction of in-plane pores in MXenes and provides an exciting opportunity for boosting their practical application for energy storage.