A Freeze-and-Thaw-Assisted Approach to Fabricate MXene/ZIF-8 Composites for High-Performance Supercapacitors and Methylene Blue Adsorption

Herein, an effective strategy was carried out to exfoliate multilayer-MXene via the gentle water freezing-and-thawing method. Following that, we designed and fabricated novel microporous Zeolitic imidazolate frameworks-8 (ZIF-8) type metal-organic frameworks hybrids incorporated with MXene by a facile layer-by-layer deposition approach which is highly desirable to overcome the severe restacking problem of MXene layers. As a supercapacitor electrode, the MXene/ZIF-8-4 composite achieved a high capacitance of 1279.5 F g ⁻¹ at 0.5 A g ⁻¹ . Moreover, the capacitance retention of MXene/ZIF-8-4 composite could maintain 90.88% after 10000 cycles at 5 A g ⁻¹ . Furthermore, asymmetrical supercapacitor has been fabricated using MXene/ZIF-8 composite as positive electrode and exhibit exceptional electrochemical performance. This device exhibits a large specific capacitance of 354.7 F g ⁻¹ at 0.5 A g ⁻¹ , and energy density of 57.84 Wh kg ⁻¹ at a power density of 0.628 kW kg ⁻¹ . In addition, MXene/ZIF-8 composites are transformed into different a loosely organized porous aerogel using freeze-drying process. As a result, the 3D porous MXene/ZIF-8 aerogels exhibit a high adsorption capacity of 459 mg g ⁻¹ to remove Methylene blue (MB).