Gold nanoparticles supported on magnesium oxide for CO oxidation

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Gold (Au) nanoparticles are crucial catalysts, but their synthesis methods influence nanoparticle size and catalytic activity.
• Magnesium oxide (MgO) is a common support material for metal catalysts.
• Controlling gold nanoparticle size is key to optimizing catalytic performance.

Purpose of the Study:

• To synthesize 1 wt% gold nanoparticles on MgO using three distinct methods: double impregnation (DIM), liquid-phase reductive deposition (LPRD), and ultrasonication (US).
• To characterize the synthesized gold nanoparticles and their support.
• To evaluate and compare the catalytic activity of the different gold nanoparticle preparations in CO oxidation.

Main Methods:

• Gold loading onto MgO support via DIM, LPRD, and US.
• Characterization techniques including N2 adsorption, temperature-programmed reduction, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD).
• Catalytic testing using CO oxidation as a model reaction.

Main Results:

• MgO support transformed into Mg(OH)2 during gold precursor loading.
• Gold nanoparticle size ranged from 2-12 nm (DIM) and 3-15 nm (LPRD, US), with average sizes of 5.4 nm (DIM) and >6.5 nm (LPRD, US).
• Catalytic activity for CO oxidation followed the order: DIM > LPRD > US.

Conclusions:

• The double impregnation method yields smaller gold nanoparticles on MgO compared to LPRD and US.
• Smaller gold nanoparticle size, achieved via DIM, correlates with higher catalytic activity in CO oxidation.
• Synthesis method is a critical factor in determining the efficacy of gold catalysts.