Enhanced catalytic nitrophenol reduction via highly porous hollow silica nanospheres stabilized Au nanoclusters

Abstract

In this work, we report the synthesis of Au nanoparticles encaged in hollow porous silica nanospheres (Au@HPSNs), which features extremely small Au nanoclusters (∼1.3 nm) encapsulated in high specific surface area (∼800 m2/g) HPSNs. We used the electrostatic attraction between the anions of poly(acrylic acid) (PAA) and protonated poly(ethylenimine) (PEI) to build the micelles system in an ethanol–water system, which was employed as the templates for deposition of silica to give the core–shell structured PEI-PAA@SiO2. The final materials Au@HPSNs were obtained by soaking PEI-PAA@SiO2 in HAuCl4 solution and subsequent calcination. The Au@HPSNs show extremely high catalytic efficiency for 4-nitrophenol (4-NP) reduction with NaBH4, and exhibit the highest heterogeneous Au-based catalytic efficiency up to date for 4-NP reduction. The greatly enhanced performance of Au@HPSNs could be ascribed to ultra-fine Au nanoclusters and the small mass transfer hindrance with high specific surface area hollow porous silica.