Hierarchically Ultrasmall Hf-Based MOF: Mesopore Adjustment and Reconstruction by Recycle Using Acid Etching Strategy

[Display omitted] •A facile top-down acid etching method for preparing nanosized (∼15 nm) HP-UiO-66-NH2(Hf) is proposed.•Tuning the size of mesopores via simply controlling the concentration of PA.•Sustainable reconstruction of mesoporous structure by reusing PA etching solution.•HP-UiO-66-NH2(Hf) displays high size-selectivity for adsorption of enzymes.•GOD@HP-UiO-66-NH2(Hf) has higher catalytic activity and enhanced stability compared to GOD@UiO-66-NH2(Hf). Benefiting from their unique properties including faster mass transfer, more exposed active sites and large molecule recognition, hierarchically porous metal–organic frameworks (HP-MOFs), in the form of ultrasmall nanoparticles (NPs) and having self-assembled interparticle mesopores, have garnered greater attention in recent years that given to typical MOFs. However, controllable synthesis of HP-MOFs on the nanoscale remains a significant challenge. Herein, for the first time, a facile top-down acid etching strategy was developed to fabricate a series of nanosized (∼15 nm) mesoporous MOF, HP-UiO-66-NH2(Hf). The sizes of mesopores in this material can be effectively tuned by simply controlling the concentration of propionic acid (PA) utilized in the preparation solution. Interestingly, the generated mesoporous HP-UiO-66-NH2(Hf) has excellent stability and can be readily constructed by using PA etching solution that has been recycled at least four times. Remarkably, HP-UiO-66-NH2(Hf) displays a high size-selectivity for adsorption of enzymes. Associated with its highly matched mesopore size, the nanocomposite generated by complexation with glucose oxidase (GOD), GOD@HP-UiO-66-NH2(Hf) has a higher catalytic activity and a significantly enhanced stability (recycled at least 7 times) in promoting oxidation of glucose compared to its MOF counterpart, GOD@UiO-66-NH2(Hf) and native GOD.