High catalytic performance of raspberry-like gold nanoparticles and enhancement of stability by silica coating

Abstract

Raspberry-like gold nanoparticles (Au RLNPs) synthesized through reduction of HAuCl₄ by using Brij35 surfactant and NaOH show high catalytic activity in the reduction of 4-nitrophenol and ethanol electrooxidation. The enhanced catalytic activity of Au RLNPs is mainly due to their high surface roughness. However, Au RLNPs are easily changed to spherical or aggregated nanoparticles by treatment with acids, thiols, and cationic surfactants (e.g., CTAB), making it difficult to sustain the catalytic activity. To improve the stability and applicability in a wide range of environments without degrading the original Au RLNP morphology, silica-coated Au RLNPs (Au RLNP@SiO₂ NPs) were successfully synthesized through a sol–gel process using poly(vinylpyrrolidone) (PVP) as a primer. In comparison with Au RLNPs and other Au nanoparticles, Au RLNP@SiO₂ NPs are more easily recovered and recycled in repeated catalytic reactions.