Yolk−Shell Catalyst of Single Au Nanoparticle Encapsulated within Hollow Mesoporous Silica Microspheres

Abstract

Synthesis and catalysis of yolk−shell microspheres containing a single Au nanoparticle core and a mesoporous shell of hollow mesoporous silica microspheres (HMSM) are reported. This synthesis employs polystyrene-co-poly(4-vinylpyridine) microspheres as both template to fabricate the HMSM shell through sol−gel process and scaffold to immobilize the Au nanoparticle. Since the single Au nanoparticle core is supernatant within the inert HMSM shell, the yolk−shell catalyst has minimum support effect and is a promising model to explore the origin of Au catalysis. Catalyzed reduction of 4-nitrophenol with NaBH4 demonstrates size-dependent induction or activation and size-dependent activity of the Au nanoparticle core of the yolk−shell catalyst.

Basic concepts and recent advances in nitrophenol reduction by gold- and other transition metal nanoparticles

“…This synthesis employs polystyrene-co-poly(4-vinylpyridine) microspheres as both template to fabricate the HMSM shell through sol-gel process and scaffold to immobilize the AuNPs. Reduction of 4-NP with NaBH 4 demonstrates a size-dependent activity of the AuNP core of the Au@HMSM yolkshell catalyst, the smaller the size of the AuNP core, the faster the conversion of 4-NP [89].…”

Hollow PDA-Au nanoparticles-enabled signal amplification for sensitive nonenzymatic colorimetric immunodetection of carbohydrate antigen 125

“…As compared to enzyme, the use of nanoparticles in immunoassays exhibits great advantages due to the low-cost, good stability, and simplicity (Tang et al 2011b;Wang et al 2012). Among various nanoparticles, gold nanoparticles (Au NPs) have been widely studied due to their good biocompatibility and high catalytic activity (Damato et al 2013;Dotzauer et al 2006;Rashid et al 2006;Wang et al 2011). …”

The impacts of nanotechnology on catalysis by precious metal nanoparticles

“…The Au nanocages were made by Au(III) etching of Ag nanocubes and thus had remaining Ag on their interior walls which could be oxidized to Ag 2 O and acted as a photocatalyst [69] . A yolk-shell type of catalyst, e.g., Au nanoparticles located inside a porous shell of SiO 2 , was prepared by Wang et al [70] . A unique aspect of the yolkshell catalyst lies in that Au has a minimum effect from the support and thus one may investigate the intrinsic catalytic properties of Au core.…”