MOFs as sacrificial templates for preparation of nanoporous carbon materials and their applications

Abstract

In recent years, nanoporous materials have attracted much attention owing to their high specific surface areas and narrow pore-size distribution. These materials have been widely used in gas storage, gas separation, catalysis and electrochemistry. Nanoporous carbon materials (NPCs), a sub-family of nanoporous materials, have been one type of the most popular functional materials. Enormous efforts have been made in the preparation of NPCs with various pore structures. Although many new NPCs have been prepared, most of them have mesoporous/macroporous/disordered structures, which limit their performance as functional materials. Therefore, the development of convenient synthetic methods to NPCs with narrower pore size at a microporous level is still a significant challenge. More recently, a novel, efficient synthetic method, thermal decomposition of metal-organic frameworks (MOFs), has been developed to obtain well-defined ordered NPCs with narrow pore sizes. MOFs have emerged as a new class of porous materials that are assembled with metal ions and organic ligands. Owing to their ordered structures, high surface areas, and large pore volumes, MOFs have been widely utilized in a variety of fields such as heterogeneous catalysis, electrochemistry, gas adsorption, and sensors. Considering the low coordination bond energy between the ligands and metal ions of MOFs, the stability of MOFs is normally lower than the traditional porous materials. MOFs have been considered as alternative precursors for the preparation of new metal oxides or carbon nanomaterials by pyrolysis. This article briefly reviews the recent progress in the preparation of these novel MOF-derived nanoporous carbons. We describe two methods to synthesize MOF-derived nanoporous carbons. One is one-step direct pyrolysis of MOFs for synthesis of nanoporous carbons. The other is introduced carbon sources into the micropores of MOFs before calcination. Furfuryl alcohol (FA), glycerol, carbon tetrachloride and ethylenediamine, and phenolic resin have been successfully employed as the carbon sources. In this review, MOFs-derived materials are classified to three species based on calcination atmosphere and metal ions, i.e., nanoporous carbons, metal/metal oxide nanoparticles embedded in a carbon matrix, and metal/metal oxide nanoparticles. At the same time, we also elaborate the applications of the porous carbon materials that are derived from MOFs as the sacrifice templates systematically. Some promising applications in, such as energy and environment-related areas, and the outlook of such types of materials are also discussed.