Controllable synthesis of silver anchored N-doped yolk-shell carbon@mSiO2 spheres and their application for the catalytic reduction of 4-nitrophenol

Core-shell materials with tunable morphology have attracted fantastic attention in practical application and scientific research. Among them, yolk-shell structured materials with mesoporous shell are considered a promising framework for catalyst support, protecting active sites from aggregation or lossing. Compared with traditional synthesis method, we report a facile strategy for preparation of functional yolk-shell materials without selective etching of the core or template. 3-Aminophenol formaldehyde resin (3-AFR) is used as the core and carbon source. The modified 3-AFR spheres are coated by mesoporous silica and silver is introduced simultaneously, obtaining yolk-shell polymer-silica composites. Then the silver doped composites are carbonized and reduced in H2/Ar atmosphere. Particularly, the final products prepared through different pre-treatments show various morphologies and the obtained materials supporting well dispersed silver nanoparticles exhibit excellent catalytic activity for 4-nitrophenol (4-NP) reduction under room temperature with conversion of >98%, which may be attributed to well dispersed Ag nanoparticles and mesoporous silica shell. This strategy may be applicable to various yolk-shell materials with assistance of pretreatment, avoiding selective removal of core or template.