The effect of hydrogen peroxide on the synthesis of terephthalate‐based metal‐organic frameworks

Abstract

Metal‐organic frameworks (MOFs) are versatile materials for applications in fields including the environment, energy and health. A synthetic route for improving the formation of MOFs has been developed and is triggered by hydrogen peroxide (H2O2) to promote the formation of terephthalate‐based MOFs of MIL‐53 and MIL‐68 types, specifically those made from Fe3+ and Al3+ and mixtures of both. Different characterization techniques (TGA, XRD, SEM, TEM, N2 porosimetry and Raman, mass and NMR spectroscopies) gave insights into the effect of H2O2 on the MOF synthesis. The reaction yield was significantly improved (the highest yield being 74 % for MIL‐53(Al)), while crystallinity and N2 adsorption properties were mostly maintained for phases based on Al and Al/Fe. Furthermore, a reaction mechanism was envisaged from the mass spectroscopic analysis of the reaction solutions, thus suggesting that H2O2 plays the role of a μ‐hydroxo bridge promoter, favoring the link between terephthalate ligands and aluminum‐containing species to give rise to the μ‐carboxylate bridges, leading to a faster growth of the final MOF, and offering a novel MOF synthesis approach.