Reticulation of 1D/2D Mo2TiC2 MXene for excellent supercapacitor performance

Abstract

Heterostructures of MXene are promising for electrochemical energy storage devices (EESDs) because of their synergistic effect and interfacial-driven properties. However, the fabrication process of MXene heterostructures based on transition metal oxides (TMOs) is very challenging due to the poor compatibility of selected materials with MXene. Herein, we fabricate a novel reticulate heterostructure (MnO2 NWs@Mo2TiC2) composed of one-dimensional (1D) ultrathin manganese oxide (MnO2) nanowires (NWs) and two-dimensional (2D) double transition metal (DTM) carbides-based MXene (Mo2TiC2) via a facile liquid-phase pre-pillaring and pillaring method. This unique heterostructure was designed by mixing pre-pillared Mo2TiC2 MXene (cetyltrimethylammonium bromide (CTAB)) and MnO2 NWs in equal mass ratios under specific experimental conditions. The MnO2 NWs not only enhance the performance but also prevent the restacking of nanosheets, while 2D Mo2TiC2 facilitates ion diffusion and ultrafast electron transport. Due to the pillaring effect of MnO2 NWs between the layers of Mo2TiC2 and the synergistic effect between MnO2 NWs and Mo2TiC2 matrix, the heterostructure exhibits a superior gravimetric capacitance for both cyclic voltammetry (CV) 918.6 F/g at 2 mV/s (459.3 C/g) and galvanostatic charge-discharge (GCD) 399.2 F/g at 1 A/g (159.7 C/g) measurements, which is significantly higher than that of pristine MXene, and also show excellent cycling stability (83.3% capacitance retention after 10000 cycles at 10 A/g). These results may open the ways to extend the research more extensively to explore the properties of double transition metal based MXenes and their composites.