Indirect fabrication of Ag nanoparticle-immobilized hollow silica composite particles and their catalysis

Abstract

A simple and effective method is proposed to prepare Ag nanoparticle-immobilized hollow silica particles (SiO2HP/AgNP composite particles). Ag2O nanoparticles are first immobilized on hollow silica particles (SiO2HP) by in situ thermolysis of AgNO3 to get SiO2HP/Ag2ONP composite particles. Then, the Ag2ONPs immobilized on SiO2HP are translated to AgNPs by chemical or thermal reduction to obtain SiO2HP/AgNP composite particles. The resultant AgNPs have ultrafine nano-size and uniform and dense distribution, which benefits from the slow and moderate reaction in the formation of Ag2ONPs. The influencing factors including the surface property of SiO2HP, mass proportion of silver salt to silica, and reaction temperature have been studied. The composite particles exhibit excellent catalytic efficiency and repeatability in 4-nitrophenol reduction. Moreover, the catalytic activity can be further enhanced by adding a trace amount of NH3 into the system, which has obvious synergies for catalysis with AgNPs.