High-throughput screening and characterization of novel zeolitic imidazolate framework gels

Abstract

Metal–organic frameworks (MOFs) are promising electrochemical energy storage materials for batteries and supercapacitors, gas storage materials, and adsorption materials for adsorption heat pumps. An obstacle to their practical application is the conversion of powdered MOFs into bulk bodies. Using MOF gels is a promising method; however, to date, only a few MOF gels have been identified for synthesis, and a unified strategy for synthesizing the desired MOF gels is unclear. This study explored the gelation conditions for zeolitic imidazolate framework (ZIF) gel synthesis using acetate by efficiently targeting multiple ZIFs via high-throughput screening and subsequent batch synthesis. Here, novel ZIF-zni and ZIF-61 gels were synthesized and characterized. These gels formed dense and mechanically rigid films on multiple substrates via simple coating and drying processes. This process has excellent industrial feasibility; therefore, the results are critical for the practical application of ZIF-zni and ZIF-61 films on desired substrates. Moreover, the unique application of the potential of the obtained ZIF-zni and ZIF-61 gels as structural adhesives for metals was investigated. The shear strength of the adhesive exceeded 30 MPa. This value exceeds those of previously reported MOF adhesives. Furthermore, using data obtained from high-throughput screening experiments, the influence of the synthesis conditions on wet gel formation, which is crucial for the realization of gel-derived films and adhesives, was evaluated through statistical modeling. Several factors like reactant concentration were estimated to have statistically significant effects on gelation, which is critical in determining the widely applicable conditions for gelation.