Exceptional oxidation activity with size-controlled supported gold clusters of low atomicity

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Catalytic activity of gold nanoparticles is highly dependent on particle size.
• Research into sub-nanometer gold clusters is a recent development enabled by advanced synthesis and characterization.

Purpose of the Study:

• To develop an easy method for preparing isolated gold atoms on functionalized carbon nanotubes.
• To investigate the catalytic performance of these gold species in the oxidation of thiophenol using O2.

Main Methods:

• Synthesis of isolated gold atoms supported on functionalized carbon nanotubes.
• Catalytic testing for thiophenol oxidation under O2.
• Characterization of gold species under reaction conditions.
• Theoretical calculations to understand reaction mechanisms.

Main Results:

• Isolated gold atoms showed no catalytic activity.
• Gold atoms aggregated into small clusters under reaction conditions, exhibiting high catalytic activity.
• Catalytic activity decreased significantly as gold clusters grew into larger nanoparticles.
• Theoretical calculations indicated simultaneous activation of thiophenol and O2 by gold clusters.
• Larger nanoparticles were passivated by strongly adsorbed thiolates, leading to loss of activity.

Conclusions:

• Gold clusters of low atomicity are highly effective catalysts for thiophenol oxidation.
• The optimal catalytic performance is achieved at the sub-nanometer cluster regime.
• Facile product desorption and simultaneous reactant activation contribute to the high efficiency of gold clusters.
• Understanding size-dependent catalysis is crucial for designing efficient nanomaterial catalysts.