In situ growth of gold nanoparticles on SiO₂/lanthanide–polyoxometalates composite spheres: An efficient catalytic and luminescent system

Graphical abstract: TEM picture of SiO_2−a/EuW₁₀/Au. - Highlights: • A method for in situ Au nanoparticles growth on luminescent spheres was developed. • The bifunctional composites show high catalytic activity and good luminescence. • HAuCl₄ solution could be reduced by luminescent composites. • The sizes of Au particles on spheres could be tuned by using different SiO₂. - Abstract: In this paper, bifunctional composite particles were synthesized by in situ grafting Au nanoparticles on the surface of SiO₂/polyethyleneimine/Eu-polyoxometalates (SiO₂/PEI/Eu-POM) spheres. It was found that the PEI layer on SiO₂/PEI/Eu-POM spheres could act as a reductant for in situ reduction of metal ions to Au nanoparticles. The sizes of Au particles grafted on spheres could be tuned by adjusting the sizes of SiO₂ spheres. The composite particles showed excellent red luminescence under UV light, which could be observed by naked eyes. In addition, they exhibited good catalytic activity in the oxidation of styrene and reduction of 4-nitrophenol. The smaller composite particles show the better overall performance in the catalytic reaction because of their lager active surface. The present strategy gives a promising way to prepare bifunctional composites for broad applications in catalysis and labeling