Synthesis and characterization of magnetic elongated hollow mesoporous silica nanocapsules with silver nanoparticles

In this study, magnetic elongated hollow mesoporous silica nanocapsules (MSNCs) with center-radial pore channels were successfully fabricated for the first time by using the surfactant-template synthesis approach. And, these novel nanomaterials were characterized by TEM, FTIR, XRD, XPS, VSM and N-2 adsorption-desorption. These well-designed mesoporous silica nanocapsules have a very high specific surface area (860 m(2) g(-1)), high pore volume (1.60 cm(3) g(-1)) and highly opened biggish pore size (8 nm). To evaluate their supporting capability in catalytic reactions, the MSNCs were then functionalized with amino groups to robustly anchor silver nanoparticles (Ag NPs) to catalyze the reduction reaction of 4-nitrophenol and 2-nitroaniline. Significantly, Ag NPs were successfully supported in the abundant pore channels of the nanocapsules without any aggregation. The well synthesized multicomponent nanocatalyst exhibited excellent catalytic activity for the reduction of 4-NP and 2-NA in water at room temperature due to the abundant and high-efficiency accessible active sites. Interestingly, the novel catalysts have gamma-Fe2O3 in the inner chamber so that they could be effortlessly recovered by magnetic separation from the reaction mixture and reused 10 times without any significant reduction in their catalytic activity. Therefore, the unique nanostructure based on the novel capsule-like mesoporous silica nanomaterial provided a useful platform for the fabrication of catalysts with superior activity, accessibility and easy recovery. And also, it is expected to be a significant template for the synthesis of other novel nanostructures.