Gold/Periodic Mesoporous Organosilicas with Controllable Mesostructure by Using Compressed CO₂

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Periodic mesoporous organosilicas (PMOs) are advanced materials with tunable structures.
• Gold nanoparticles (Au NPs) exhibit unique catalytic properties.
• Controlling nanoparticle confinement within porous frameworks is crucial for enhanced performance.

Purpose of the Study:

• To fabricate gold nanoparticles confined within periodic mesoporous organosilicas (PMOs) with controllable morphologies.
• To investigate the influence of carbon dioxide (CO2) pressure on PMO structure and Au NP confinement.
• To evaluate the catalytic performance of the synthesized Au-based PMOs for 4-nitrophenol reduction.

Main Methods:

• One-pot synthesis using HAuCl4, organosilica precursors, P123 template, and compressed CO2.
• Characterization via Transmission Electron Microscopy (TEM), N2 adsorption, and X-ray Diffraction (XRD).
• Evaluation of catalytic activity through the reduction of 4-nitrophenol (4-NP).

Main Results:

• Successfully fabricated gold nanoparticles confined within PMO walls with controllable morphologies (nanotube, hexagonal, vesicle-like, cellular foam) by varying CO2 pressure.
• Demonstrated morphology-dependent catalytic activity, high conversion rates, and excellent thermal stability for 4-NP reduction.
• Proposed a mechanism for mesostructure evolution of PMOs influenced by CO2 pressure.

Conclusions:

• The one-pot synthesis method effectively confines gold nanoparticles within PMOs.
• CO2 pressure is a critical factor in controlling PMO mesostructure and Au NP morphology.
• Au-based PMOs show promising catalytic applications with morphology-dependent properties.