Multilayer Superlattices of Monolayer Mesoporous Carbon Framework-Intercalated MXene for Efficient Capacitive Energy Storage

Incorporating conductive and porous components as pillaring materials into the interlayers of two-dimensional (2D) materials offers a solution to the restacking issue and enables the creation of multifunctional hetero-superstructures. Here, multilayer MXene superlattices intercalated with monolayer mesoporous carbon frameworks (MMCFs) are synthesized by colloidal co-assembly of MXene Ti3C2Tx nanosheets and Fe3O4 nanoparticles. The intercalated MMCFs not only increase interlayer spacing and create porous channels for fast mass transport but also act as conductive pillars to facilitate electron transfer along the z-direction. These unique structural features allow for the full utilization of unilamellar MXene, making the resulting Ti3C2Tx/MMCF superlattices particularly suitable for capacitive energy storage in organic electrolytes containing bulky ions. As a demonstration, supercapacitors made from Ti3C2Tx/MMCFs exhibit a volumetric capacitance of 317 F cm-3 in a tetraethylammonium tetrafluoroborate/propylene carbonate electrolyte. Furthermore, on-chip micro-supercapacitors (MSCs) fabricated from Ti3C2Tx/MMCFs, using the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate as an electrolyte, achieve an areal energy density of 0.10 mWh cm-2, surpassing that of most state-of-the-art MXene-based MSCs developed to date. This study not only highlights the significant potential of Ti3C2Tx/MMCFs for efficient capacitive energy storage in organic electrolytes but also introduces a new method for synthesizing 2D porous hetero-superstructures for various applications. This work proposes a precise colloidal co-assembly method that bridges unilamellar MXene with monolayer mesoporous carbon frameworks (MMCFs), forming MXene/MMCF multilayer superlattices. On-chip micro-supercapacitors fabricated from Ti3C2Tx/MMCFs achieve remarkable areal energy density, benefiting from the full utilization of unilamellar MXene enabled by the intercalated MMCFs.image