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Presently, two‐dimensional (2D) metal–organic framework (MOF) are drawing increasing attention in energy‐storage areas. However, more and complexed factors would affect the nucleation and growth of 2D MOFs, and subsequently affect the final performance. Particularly, it is important to control the coordination rate between ions and ligands. In this paper, MXene was directly used as titanium source to coordinate with an organic ligand to form Ti‐MOF sheets. To further boost the performance, mesopores were introduced in preparing 2D Ti‐MOF, constructing hierarchical porous Ti‐MOF@Ti3C2TX hybrids. Results showed that diffusion‐controlled behaviors play a dominant role over surface capacitive behaviors during the charge storage process of the hierarchical porous hybrids. A hybrid supercapacitor (HSC) assembled with the obtained HP‐Ti‐MOF@Ti3C2TX and activated carbon (AC) exhibited an energy density of 22.9 Wh kg−1 at a power density of 850 W kg−1 (1 A g−1), and a power density of 4.25 kW kg−1 at an energy density of 15.3 Wh kg−1 (5 A g−1). The present strategy is expected to provide design ideas for novel energy‐storage electrode materials. [ABSTRACT FROM AUTHOR]

• The nanostructured 3DPC/Co 3 O 4 composites were prepared. • Amorphous and hierarchical structure enhanced ion and electron transport. • Oxygen-deficient Co 3 O 4 state provided more active sites. • The 3DPC/Co 3 O 4 delivered enhanced electrochemical performance. The three-dimensional porous carbon (3DPC)/Co 3 O 4 composites were prepared via pyrolysis of 3D graphene/Co-MOF precursor. The rich carbon content, amorphous state and hierarchical porous structure remarkably accelerated electron and ion transport. The oxygen-deficient Co 3 O 4 state provided more active sites. Consequently, the 3DPC/Co 3 O 4 electrode delivered enhanced capacitive performance owing to these advantages, which exhibited a high specific capacitance of 423 F g−1 at 1 A g−1, good rate capability of 85.7% capacitance retention even at 10 A g−1, and ideal durability with about 17% capacitance decay after 2000 cycles. Moreover, the 3DPC/Co 3 O 4 //AC asymmetric supercapacitor exhibited a broad potential window of 1.7 V and a maximum energy density of 21.1 Wh kg−1 with a power density of 790 W kg−1. [ABSTRACT FROM AUTHOR]

Recently, two-dimensional metal-organic frameworks (2D MOFs) are drawing increasing attention in energy storage area. Specially, hybrid 2D MOF-based heterostructures have greatly promoted the development of MOF-based electrode materials. However, the underutilization of both abundant active sites and high surface area causes 2D MOFs poor performance and thus restricts their practical application. Herein, to shorten the ion transport paths and enhance the ion diffusion ability, mesopores were introduced into 2D Zn-MOF sheets to construct a hierarchical porous Zn-MOF-based heterostructure. The energy-storage mechanism in the heterostructures was deeply investigated and the importance of the introduced-mesopores on enhancing the electrochemical behaviors was confirmed. With the optimized design, the obtained Meso-Zn-MOF@rGO-PBA delivered outstanding electrochemical performance, including a high capacitance (292.8 F g−1 at 0.2 A g−1), an excellent rate capacity (268.1 F g−1 at 5 A g−1) and a good cycling stability (83.2 % retention after 2000 cycles). Furthermore, the practical applicability of Meso-Zn-MOF@rGO-PBA was researched by assembling an asymmetric supercapacitor using activated carbon as the other electrode, achieving a satisfied specific capacitance of 54.9 F g−1 with an energy density of 19.5 Wh kg−1 (1 A g−1). Our observation provides a strategic design idea for high-performance supercapacitor electrode materials. [Display omitted] • By introducing mesopores into 2D MOF-hybrid heterojunctions to develop novel electrode materials. • Conductive rGO-PBA lowered the internal resistance of electrodes and heightened the capability of producing capacitance. • Introduced-mesopores greatly promoted the synchronous enhancement of both pseudocapacitive and double-layer capacitance. • Meso-Zn-MOF@rGO-PBA delivered high capacitance (292.8 F g−1 at 0.2 A g−1) and good rate capacity (268.1 F g−1 at 5 A g−1). [ABSTRACT FROM AUTHOR]