Reduced thermal expansion by surface-mounted nanoparticles in a pillared-layered metal-organic framework

Abstract

Control of thermal expansion (TE) is important to improve material longevity in applications with repeated temperature changes or fluctuations. The TE behavior of metal-organic frameworks (MOFs) is increasingly well understood, while the impact of surface-mounted nanoparticles (NPs) on the TE properties of MOFs remains unexplored despite large promises of NP@MOF composites in catalysis and adsorbate diffusion control. Here we study the influence of surface-mounted platinum nanoparticles on the TE properties of Pt@MOF (Pt@Zn2(DP-bdc)2dabco; DP-bdc2-=2,5-dipropoxy-1,4-benzenedicarboxylate, dabco=1,4-diazabicyclo[2.2.2]octane). We show that TE is largely retained at low platinum loadings, while high loading results in significantly reduced TE at higher temperatures compared to the pure MOF. These findings support the chemical intuition that surface-mounted particles restrict deformation of the MOF support and suggest that composite materials exhibit superior TE properties thereby excluding thermal stress as limiting factor for their potential application in temperature swing processes or catalysis.

CO2 and Temperature Induced Switching of a Flexible Metal-Organic Framework with Surface-Mounted Nanoparticles

“…It has been found that linker rotation can influence conversion and selectivity for Pt@ZIF-8 materials used in catalysis; 43 however, to the best of our knowledge the inverse question of how flexibility in MOFs is affected by NPs has not been investigated outside of a recent study from us where we focused on the thermal expansion properties of Pt@MOF composites. 44 The research areas of NP loaded MOF materials and switchable, flexible MOFs are yet not interlinked while scenarios in which network switching regulates catalysis conditions at the NPs, and in which NPs direct framework switching behavior can easily be envisioned. Therefore, we see great potential in forming this link.…”