Zeolitic imidazolate framework (ZIF)-derived porous carbon materials for supercapacitors: an overview

Abstract

The present analysis focuses on the synthetic methods used for the application of supercapacitors with various mysterious architectures derived from zeolitic imidazolate frameworks (ZIFs). ZIFs represent an emerging and unique class of metal-organic frameworks with structures similar to conventional aluminosilicate zeolites, consisting of imidazolate linkers and metal ions. Their intrinsic porous properties, robust functionalities, and excellent thermal and chemical stabilities have resulted in a wide range of potential applications for various ZIF materials. In this rapidly expanding area, energetic research activities have emerged in the past few years, ranging from synthesis approaches to attractive applications of ZIFs. In this analysis, the development of high-performance supercapacitor electrodes and recent strategies to produce them, including the synthesis of various heterostructures and nanostructures, are analyzed and summarized. This analysis goes via the ingenuity of modern science when it comes to these nanoarchitecture electrodes. Despite these significant achievements, it is still difficult to accurately monitor the morphologies of materials derived from metal-organic frameworks (MOFs) because the induction force during structural transformations at elevated temperatures is in high demand. It is also desirable to achieve the direct synthesis of highly functionalized nanosized materials derived from zeolitic imidazolate frameworks (ZIFs) and the growth of nanoporous structures based on ZIFs encoded in specific substrates for the construction of active materials with a high surface area suitable for electrochemical applications. The latest improvements in this field of supercapacitors with materials formed from ZIFs as electrodes using ZIFs as templates or precursors are discussed in this review. Also, the possibility of usable materials derived from ZIFs for both existing and emerging energy storage technologies is discussed.

Fig. 1. Ragone plots of different energy storage systems.

Fig. 2. Representation of various supercapacitors: (a) electrical double-layer capacitors (EDLCs); (b) pseudo-capacitors (PCs) (where M exemplifies a metal atom; if electrolyte anions participate in reversible redox reactions, they move in the opposite route to the cations).

Fig. 3. Strategies adopted for the improvement of electrode performance.

Fig. 4. Production of ZIF-8 and ZIF-67-derived nanoporous carbon and its advantages and disadvantages. Reproduced with permission from the American Chemical Society, ref. 63, Copyright 2015.

Fig. 5. Summary of the synthetic methods to convert ZIFs to ZIF-derived NPC and MO materials.

Fig. 6. (a) Preparation of Zn/Co-ZIFs and (b) colors of Zn/Co-ZIFs with various compositions; (c) TEM image, (d) elemental mapping and (e) SEM image of Zn/Co-ZIFs. Reproduced with permission from ref. 72, Copyright 2016, Nature Publishing Group.

Fig. 7. Synthesis of a Co/Zn hybrid MOF and nano-porous carbon. (a) Preparation of Co/Zn (2 : 1) hybrid-ZIF from a metal precursor and 2-methylimidazole organic linker followed by carbonization to produce graphitic and amorphous nanoporous carbons. (b) Pictures of 2 L-scale production. SEM images of (c) a bimetallic Co/Zn hybrid ZIF and (d) carbonized nano-porous carbon. Reproduced with permission from the Royal Society of Chemistry ref. 78, copyright 2016.

Fig. 8. Representation of the preparation of nanoporous carbons and nano-porous Co₃O₄ from ZIF-67 as a precursor, which shows the retention of the morphology of the parent ZIF-67, as shown in the SEM and TEM images. Reproduced with permission from American Chemical Society, ref. 35, Copyright 2015.

Fig. 9. SEM images of before (a) and after (b and c) the synthesis of ZIF-67 derived n-doped CNTs decorated with sulfur and nickel hydroxide, (d) specific capacitance calculated from CV curves as a function of scan rate for the Co/NC, Co/NC/S, and Co/NC/S@NH electrodes, (e) Bode phase angle plots of synthesized electrodes on Ni foam. Reproduced with permission from Elsevier, ref. 40, and Copyright 2020.

Fig. 10. TEM images of (a–c) Ce-MOF/GO, (d) cyclic voltammetry response of the Ce-MOF/GO composite at various scan rates in 3 M KOH electrolyte, (e) galvanostatic charge–discharge behavior in 3 M KOH electrolyte, and (f) Ragone plots of the Ce-based composites. Reproduced with the approval from ref. 136, Copyright 2018, the Royal Society of Chemistry.

Fig. 11. (a) Specific capacitance of NiCo-LDH/NF (α and β) at different current densities; (b) retention capacity; (c) comparison of the XRD patterns of NiCo-LDH/NF (β) before and after the life cycles; (c and d) SEM and TEM images of NiCo-LDH/NF, respectively. Reproduced with the approval from ref. 24, Copyright 2019, Elsevier.