Self-propagating fabrication of 3D porous MXene-rGO film electrode for high-performance supercapacitors

2D MXene nanosheets with metallic conductivity and high pseudo-capacitance are promising electrode materials for supercapacitors.Especially,MXene films can be directly used as electrodes for flexible supercapacitors.However,they suffer from sluggish ion transport due to self-restacking,causing limited electrochemical performance.Herein,a flexible 3D porous MXene film is fabricated by incorporating graphene oxide(GO) into MXene film followed by self-propagating reduction.The self-propagating process is facile and effective,which can be accomplished in 1.25 s and result in 3D porous framework by releasing substantial gas instantaneously.As the 3D porous structure provides massive ion-accessible active sites and promotes fast ion transport,the MXene-rGO films exhibit superior capacitance and rate performance.With the rGO content of 20%,the MXene-rGO-20 film delivers a high capacitance of 329.9 F g^(-1) at 5 mV s^(-1) in 3 M H2 SO4 electrolyte and remains 260.1 F g^(-1) at 1,000 mV s^(-1) as well as good flexibility.Furthermore,the initial capacitance is retained above 90% after 40,000 cycles at 100 A g^(-1),revealing good cycle stability.This work not only provides a high-performance flexible electrode for supercapacitors,but also proposes an efficient and time-saving strategy for constructing 3D structure from 2D materials.