Chitosan as capping agent in a robust one-pot procedure for a magnetic catalyst synthesis

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Developing efficient and recoverable catalysts is crucial for sustainable chemical synthesis.
• Chitosan (CS), a natural polymer, offers biocompatibility and unique properties for nanomaterial functionalization.
• Magnetically recoverable catalysts simplify separation and recycling processes.

Purpose of the Study:

• To synthesize magnetically recoverable nanoparticles (NPs) of ruthenium (Ru) or silver (Ag) stabilized by chitosan (CS).
• To evaluate the catalytic performance of these CS-capped NPs in the reduction of 4-nitrophenol.
• To assess the stability and reusability of the developed catalysts.

Main Methods:

• A one-pot solvothermal method was employed using triethyleneglycol (TEG) as a solvent.
• Iron oxide NPs were formed in situ in the presence of CS and iron acetylacetonate.
• Ru or Ag species were coordinated and NPs formed in the same reaction solution.
• Catalytic activity was tested using the reduction of 4-nitrophenol with sodium borohydride (NaBH4).

Main Results:

• Monodisperse 2.2 nm ruthenium NPs (Ru0 and Ru4+ species) were successfully stabilized by CS.
• Chitosan proved less effective for stabilizing Ag NPs, resulting in larger nanocrystals.
• The CS-Ru catalyst with 2.2 nm Ru NPs showed the highest catalytic activity for 4-nitrophenol reduction.
• The catalyst exhibited excellent shelf-life (10 months) and reusability over ten cycles with easy magnetic separation.

Conclusions:

• The developed one-pot method efficiently produces magnetically recoverable CS-Ru catalysts.
• The 2.2 nm CS-Ru NPs are highly active, stable, and reusable for nitroarene reduction.
• The catalyst's properties, combined with environmentally friendly fabrication, make it promising for industrial applications.