Search

[Display omitted] • Hierarchical porous MXene/TiO 2 -Fe-G aerogel is prepared via a hydrothermal strategy. • The EmimTFSI-ACN-LiTFSI electrolyte is formulated to match the electrode material. • MXene/TiO 2 -Fe-G exhibits enhanced specific capacitance and good rate capability. • Fabricated ASC achieves energy density of 54 Wh kg−1 at power density of 1737 W kg−1. To achieve pseudocapacitance by driving reversible redox reactions is scientifically appealing to realize high energy density of supercapacitors (SCs). In this work, a unique ferric ions-assisted self-assembly MXene/TiO 2 -graphene aerogel composite (MXene/TiO 2 -Fe-G) is developed. The MXene/TiO 2 -Fe-G composite has a 3D hierarchical porous framework, large accessible specific surface area, and amorphous TiO 2 modified on the surface of MXene nanosheets. Importantly, amorphous TiO 2 , generated from the partial oxidation of MXene, can contribute enormous pseudocapacitance via the reversible redox reaction with Lithium ions. In addition, ferric cations with variable valence states can also provide pseudocapacitance. A trinary ionic liquid-based electrolyte (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide-acetonitrile-lithium bis(trifluoromethanesulfonyl)imide, EmimTFSI-ACN-LiTFSI) with a wide electrochemical stability potential window is also formulated to match the new material. Consequently, the MXene/TiO 2 -Fe-G composite as the negative electrode shows a superb specific capacitance of 196.4 F g−1 at 1 A g−1. An asymmetric supercapacitor assembled with the MXene/TiO 2 -Fe-G anode and self-synthesized nitrogen-doped reduced graphene oxide aerogel (N-RGA) cathode can deliver a high energy density of 54 Wh kg−1 at a high-power density of 1737 W kg−1. This work provides a possibility of implementing pseudocapacitance by changing the morphology and structure of MXene composites to match the ionic liquid-based electrolyte, which can considerably enhance the performance of MXene-based SCs. [ABSTRACT FROM AUTHOR]

• Stable ionic liquid hybrid Al-fum MOF materials were prepared by simple impregnation approach. • [C 2 N][Zn 3 Cl 7 ]@Al-fum-60% exhibit an exceptionally high uptake at high temperature (9.9 mmol/g at 80 °C, 8.8 mmol/g at 100 °C) • [C 2 N][Zn 3 Cl 7 ]@Al-fum-60% have an excellent selective separation performance of NH 3 from NH 3 /CO 2 mixture at 80 °C. • Coordination interactions of NH 3 to Zn centre is the key driven force for the adsorption and selective separation. Efficient adsorption and selective separation of ammonia at high temperature is a crucial and challenging issue. In this work, a series of stable ionic liquid hybrid materials have been developed by simple impregnation of ionic liquids into stable metal–organic framework Al-fum with 1D pores. The hybrid material [C 2 N][Zn 3 Cl 7 ]@Al-fum-60% exhibited an exceptionally high uptake (9.9 mmol/g at 80 °C, 8.8 mmol/g at 100 °C) at high temperature, excellent uptake (9.8 mmol/g at 25.0 °C) at low ammonia concentration (100,000 ppm), and remarkable selective separation performance (selectivity factor is 25.1) of NH 3 from NH 3 /CO 2 mixture at high temperature. The NH 3 uptake of [C 2 N][Zn 3 Cl 7 ]@Al-fum-60% at 100 °C was higher than the capacity of most of typical porous NH 3 adsorbents at room temperature. It is revealed that such superior NH 3 capacity and selective separation performance are mainly attributed to coordination interactions of NH 3 to Zn centre of the ionic liquids and the hydrogen bonding interactions of NH 3 with Cl of the ionic liquids and NH 3 with μ-OH of Al-fum. [ABSTRACT FROM AUTHOR]