Tuning the Properties of MOF-808 via Defect Engineering and Metal Nanoparticle Encapsulation.

Rifan Hardian,Stefano Dissegna,Marie‐Vanessa Coulet,Aladin Ullrich,Philip L Llewellyn,Roland A Fischer

doi:10.1002/chem.202005050

Abstract

Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the reactivity of metal–organic frameworks. In this work, various MOF‐808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF‐808 is quantified with water adsorption and CO2 adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF‐808 towards water and could also be advantageously used to tune adsorption properties of this MOF family.

Highlights

Metal–organic frameworks (MOFs) have attracted much attention in recent years due to their use in a wide range of applications from gas storage and separations,[1,2] catalysis,[3,4,5] mechanics,[6,7] to drug delivery,[8] to name just a few
The general procedures to synthesize MOF-808 samples were adapted from refs. [32] and [35]
The nanoparticles were synthetized using H2PtCl6.6H2O as Pt precursor and PVP as stabilizer The procedure was adapted from refs. [36, 37, 38], and is described in Supporting Information. Prior to their use in the MOF synthesis, Pt nanoparticles (Pt-NPs) were characterized in depth, and TEM observations evidenced that the Pt nanoparticles possess an average diameter of 3.5 nm

Summary

Introduction

Metal–organic frameworks (MOFs) have attracted much attention in recent years due to their use in a wide range of applications from gas storage and separations,[1,2] catalysis,[3,4,5] mechanics,[6,7] to drug delivery,[8] to name just a few. Apart from the extensively studied UiO-66, there exist other zirconium-based MOFs with a different number of connectivity’s and variable topologies.[17,28] One can cite NU-1000 that has an 8-connectivity with csq topology[29] and MOF-808 characterized by a 6-connectivity with spn topology.[30] MOF-808 with hexanuclear zirconium is of particular interest because of its lower node-connectivity that can provide more accessible open metal sites, especially if missing linker defects are engineered into the framework This MOF is constructed from zirconium clusters linked together through trimesic acid or ben-. This investigation highlights the complex interplay between the synthesis, morphology, texture, and chemistry of the materials which influence their sorption properties

Results and Discussion

Conclusions

Conflict of interest