Locking Effect in Metal@MOF with Superior Stability for Highly Chemoselective Catalysis

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Ultrasmall metal nanoparticles (NPs) offer high catalytic activity but suffer from aggregation and loss, reducing chemoselectivity and efficiency.
• Metal-organic frameworks (MOFs) can confine NPs, but strategies are needed to prevent NP deactivation and maintain performance.

Purpose of the Study:

• To develop a locking effect strategy for synthesizing high-loading, ultrafine metal NPs within MOFs for stable and efficient chemoselective catalysis.
• To investigate the use of interlocked MOF structures to confine gold nanoparticles (Au NPs) for enhanced catalytic performance.

Main Methods:

• A locking strategy was employed using ZIF-90 MOF with aldehyde groups and diamine chains, forming an interlocked structure via aldimine condensation.
• Gold nanoparticles (Au NPs) were formed *in situ* within the locked MOF (Au@L-ZIF-90) to create a stable catalytic system.
• Density functional theory (DFT) calculations and experimental characterization were used to analyze the catalyst's structure and electronic properties.

Main Results:

• The optimized catalyst (Au@L_a-ZIF-90) featured highly dispersed Au NPs (2.60 ± 0.81 nm) with a high loading (22 wt %).
• The catalyst demonstrated excellent performance in the selective hydrogenation of 3-nitrophenylacetylene (3-NPA) to 3-aminophenylacetylene (3-APA), achieving 99% yield and 99% selectivity.
• The locked MOF structure modulated the charge of Au NPs, enhancing specificity for nitro group hydrogenation and providing excellent durability over 20 cycles.

Conclusions:

• The locking effect strategy provides a robust method for stabilizing ultrafine metal NPs within MOFs, overcoming limitations of aggregation and loss.
• This approach enables highly efficient and selective chemocatalysis, as demonstrated by the superior performance in 3-APA synthesis.
• The strategy is versatile and applicable to various metal NPs and MOFs, offering a universal platform for designing advanced catalysts with tunable properties.