Facile preparation of small-sized gold nanoparticle decorated silica nanocomposites and their morphological changes in catalytic reactions

Abstract

Due to the unique physicochemical properties of gold nanoparticles (AuNPs) decorated silica nanostructures (SiO2@AuNPs), they show great potential for applications in catalysis, biosensing, optical devices and medicine. It is essential to explore the catalytic effect of SiO2@AuNPs and the understanding of the essential process of catalytic reactions. We have prepared SiO2@AuNPs by loading small-sized AuNPs on surface-modified silica nanospheres. SiO2@AuNPs was used as a catalyst for the catalytic reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4, and the results showed that with the increase of the amount of catalyst from 30 µL to 100 µL, the corresponding rate constant Kapp was increased from 6.44×10-3 s-1 to 1.45×10-2 s-1, and its TOF was as high as 1.326 × 103 h-1, and the catalytic rate could still be maintained at 87% after five cycles. By analyzing the morphology and size of the SiO2 supported AuNPs before and after the catalytic reaction, it can be seen that the atoms on the surface of small-sized AuNPs supported by silica have migrated during the catalytic process, which subsequently affects the catalytic efficiency of the structure. This study proves the good catalytic effect of SiO2@AuNPs structure and lays the foundation for its wider application.