Catalytically Active Silicon Oxide Nanoclusters Stabilized in a Metal-Organic Framework

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable porous structures for material functionalization.
• Post-synthetic modification allows for the introduction of specific functionalities into MOFs.
• Bulk silicon dioxide is generally considered catalytically inactive.

Purpose of the Study:

• To functionalize the zirconium-based MOF NU-1000 with silicon oxide clusters using atomic layer deposition (ALD).
• To investigate the catalytic activity of the resulting silicon oxide functionalized MOF (Si-NU-1000).
• To compare the catalytic performance of Si-NU-1000 with aluminum oxide-based catalysts.

Main Methods:

• Post-synthetic modification of NU-1000 using ALD with tetramethoxysilane.
• Characterization of the Si-NU-1000 material using X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR).
• Evaluation of catalytic activity and comparison with Al-NU-1000 and bulk γ-Al2O3.

Main Results:

• Successful incorporation and stabilization of few-atom silicon oxide (SiO_x) clusters within the MOF pores.
• Si-NU-1000 demonstrated significant catalytic activity, unlike bulk SiO₂.
• Si-NU-1000 exhibited higher catalytic activity than Al-NU-1000 and bulk γ-Al₂ O₃.
• XPS and IR revealed an electron-donating nature of the nanosized SiO_x clusters, correlating with high activity.

Conclusions:

• Nanosized silicon oxide clusters exhibit unique electronic properties and high catalytic activity.
• ALD modification of MOFs is an effective strategy for creating advanced catalytic materials.
• Si-NU-1000 presents a promising alternative to conventional acidic catalysts.