Au–CuxOy Nanoparticles Encapsulated in Hollow Porous Silica Nanospheres as Efficient Catalysts for Nitrophenol Reduction

Abstract

In this work, Au–CuxOy hybrid nanoparticle-encapsulated hollow porous silica nanospheres (Au–CuxOy in HPSNs) were synthesized by immobilizing the catalytic functionality inside hollow cavities by using polyethyleneimine in a reverse microemulsion system as the void template as well as the platform to deliver the metals into the central voids. Compared with individual Au in HPSNs and CuxOy in HPSNs, the prepared Au–CuxOy in HPSNs demonstrate significantly improved catalytic efficiency for the reduction of various nitrophenols with NaBH4. At the molar ratio of 4-nitrophenol/Au of 30/1, the 4-nitrophenol conversions over Au–CuxOy in HPSNs reach 100% within 5.5 min, and catalytic efficiency is maintained during five cycles of catalytic reactions. The enhanced performance can be ascribed to the synergistic effect between Au and CuxOy, and the protection of silica shells to inner Au–CuxOy improve their catalytic stability.