Insights into inorganic buffer layer-assisted in situ fabrication of MOF films with controlled microstructures

Abstract

In this study, it was demonstrated that the introduction of Co–Al/Mg–Al hydrotalcite-like compound buffer layers on porous α-Al₂O₃ substrates enabled effective manipulation of the microstructure of ZIF-7 films so that metal ions located in the inorganic buffer layers were not necessarily identical with those residing in the MOF crystals. Moreover, zinc sources were found to exert a significant influence on the final microstructure of the prepared ZIF-7 films. In addition to ZIF-7, well-intergrown ZIF-8 and HKUST-1 films could also be in situ grown on diverse HTlc buffer layer-modified α-Al₂O₃ substrates, which convincingly demonstrated the generality of this strategy for the facile preparation of qualified MOF films/membranes.