Synthesis and characterization of noble metal nanoparticles/kaolinite composites

Abstract

Silver, palladium, and rhodium nanoparticles were prepared by heterogeneous nucleation in the interlamellar space of a layered kaolinite support. Disaggregation of the lamellae of nonswelling kaolinite was achieved by intercalation of dimethyl sulfoxide. The kaolinite was suspended in various metal precursor solutions and the adsorbed metal cations were reduced with NaBH₄.The diameter of the silver particles (4–10 nm) prepared in this way depends on the initial Ag⁺> concentration. Palladium and rhodium particles were stabilized by polymers and by the lamellae of kaolinite. The effect of the molecular mass and the concentration of the polymers on the size of the particles formed was studied using neutral poly(vinylpyrrolidone). The effect of the concentration of the precursor was also examined. The average particle size fell in the range 1–3 nm, depending on the stabilization method used and the concentration of precursor ions. Interlamellar incorporation of nanoparticles was monitored by X-ray diffraction, and was verified by transmission electron microscopy and small-angle X-ray scattering.

Acknowledgements The authors thank for the financial support of the Hungarian National Scientific Found (OTKA M036688).