In situ growth of gold nanoparticles onto polyphosphazene microspheres with amino-groups for alcohol oxidation in aqueous solutions

• Amino-terminated polyphosphazene microspheres were easily fabricated.
• The PZS-NH2 microspheres act as both reductant and stabilizer.
• The Au nanoparticles possess uniform size and good dispersibility.
• The Au/PZS-NH2 composites show high catalytic activity and good recyclability.

Cross-linked polyphosphazene microspheres with amino-groups have been successfully prepared by precipitation polymerization of hexachlorocylotriphosphazene and 4,4′-diaminodiphenyl ether. Then Au nanoparticles (Au NPs) were synthesized by in situ growth on the surface of amino-terminated polyphosphazene (PZS-NH2) microspheres, which serve as a reducer and a stabilizer. The PZS-NH2 microspheres and the Au/PZS-NH2 composites were characterized by scanning electron microscopy, FT-IR spectrum, transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. The results showed that Au NPs with good dispersibility and uniform size were well located on the surfaces of the PZS-NH2 microspheres. The catalytic performance of the Au/PZS-NH2 composites was studied in the oxidation of alcohols to the corresponding carboxylic acids with air as the oxidant in aqueous solutions. More than 94% conversion of alcohol was obtained at the reaction temperature of 50 °C for 24 h. The Au/PZS-NH2 catalyst was recycled six times without loss of catalytic activity.

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