Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites

Abstract

Based on the synergistic photocatalytic activities of nano-sized TiO₂ and Ag, as well as the magnetic properties of Fe₃O₄, a sea urchin-like Fe₃O₄@TiO₂@Ag nanocomposite (Fe₃O₄@TiO₂@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO₂ nanofiber, higher structural stability and larger specific surface area. Here, Fe₃O₄@TiO₂@Ag NCs are obtained with Fe₃O₄ as the core and nanofiber TiO₂/Fe₃O₄/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO₂ nanofibers and inside the cavities of sea urchin-like Fe₃O₄@TiO₂ nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO₂/Fe₃O₄/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO₂, while the Fe₃O₄ cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO₂/Fe₃O₄/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future.