Facile preparation of small-sized gold nanoparticle decorated silica nanocomposites and their morphological changes...

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 to 100μl, the corresponding rate constantK_appwas increased from 6.44 × 10^-3to 1.45 × 10^-2s^-1, and its TOF was as high as 1.326 × 10³h^-1, and the catalytic rate could still be maintained at 87% after five cycles. By analyzing the morphology and size of the SiO₂supported 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.