A performance study of enhanced visible-light-driven photocatalysis and magnetical protein separation of multifunctional yolk-shell nanostructures

Synthesis of functional yolk-shell nanostructures (YSNs) containing SiO2 nanoparticle yolk and a mesoporous shell of NiTiO3 is reported. SiO2@TiO2 core-shell spheres were first prepared via a sol-gel approach, and then a Ni(OH)(2) nanowhisker was deposited on the surface of a TiO2 layer and SiO2 nanoparticle-core etching took place simultaneously in a H2O-ethanol-ammonia solution reaction, and then a SiO2@void@TiO2@Ni(OH)(2) structure was obtained. Finally, the TiO2@Ni(OH)(2) shell was transformed into the NiTiO3 shell via calcination treatment, and the SiO2@NiTiO3 YSNs were achieved. The chemical composition and photoresponsive properties of the SiO2@NiTiO3 yolk-shell material can be easily tailored by adjusting the molar ratio of the Ni/Ti precursors. Their visible-light-induced photocatalytic activities were evaluated by the degradation of methylene blue. The SiO2@NiTiO3 YSNs exhibited enhanced and stable photocatalytic performance due to the unique yolk-shell structure, large surface area, fast diffusion of reactants, and multiple reflections of visible light within the sphere interior voids. Furthermore, the present synthesis method can be extended to the preparation of other functional YSNs, such as magnetic YSNs consisting of SiO2-coated Fe3O4 yolk and a Ni(OH)(2)-coated TiO2 shell, for the application of magnetic separation of proteins.