Functional Zeolitic-Imidazolate-Framework-Templated Porous Carbon Materials for CO2 Capture and Enhanced Capacitors

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Abstract

Three types of zeolitic imidazolate frameworks (ZIFs) with different topological structures and functional imidazolate-derived ligands, namely, ZIF-8, ZIF-68, and ZIF69, have been directly carbonized to prepare porous carbon materials at 1000 °C. These as-synthesized porous carbon materials were activated with fused KOH to increase their surface areas and pore volumes for use in gas storage and supercapacitors. The relationship between the local structure of the products and the composition of the precursors has been investigated in detail. The BET surface areas of the resultant activated carbon materials are 2437 (CZIF8a), 1861 (CZIF68a), and 2264 m2 g−1 (CZIF69a). CZIF8a exhibits the highest H2-storage capacities of 2.59 wt. % at 1 atm and 77 K, whereas CZIF69a has the highest CO2 uptake of 4.76 mmol g−1 at 1 atm and 273 K, owing to its local structure and pore chemical environment. The specific capacities are calculated from the CV curves. CZIF69a exhibits the highest supercapacitor performance of 168 F g−1 at a scan speed of 5 mV s−1. These results indicate that the functional chloride group on the benzimidazolate ligand plays a very important role in improving the surface area, pore volume, and, therefore, CO2-capture and supercapacitor properties of the corresponding porous carbon materials.

Abstract

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