Synthesis of a novel narrow-band-gap iron(II,III) oxide/titania/silver silicate nanocomposite as a highly efficient and stable visible light-driven photocatalyst.

Ag6Si2O7, a visible light-driven photocatalyst, has attracted considerable attention owing to its enormous environmental remediation potential. In this work, a magnetic iron(II,III) oxide/titania/silver silicate (Fe3O4/TiO2/Ag6Si2O7) nanocomposite was synthesized by anchoring TiO2 and Ag6Si2O7 on the surface of Fe3O4 nanoparticles. The morphology, crystal structure, as well as the spectroscopic, magnetic, and photocurrent properties of the as-prepared Fe3O4/TiO2/Ag6Si2O7 nanocomposite were studied. Methylene blue (MB) was used for evaluating the photocatalytic performance under simulated visible light. The Brunauer-Emmett-Teller (BET) surface area, total pore volumes, and average pore diameter of the Fe3O4/TiO2/Ag6Si2O7 nanocomposite were calculated to be 33.077 m2/g, 0.099 cm3/g, and 15.45 nm, respectively. The Fe3O4/TiO2/Ag6Si2O7 photocatalyst showed a narrow-band-gap (1.38 eV) while exhibiting excellent photocatalytic performance with a photocurrent of 9.4 µA/cm2 under simulated visible light. Furthermore, the nanocomposites showed high resistance to degradation (i.e., more than 80%) after 5 reaction cycles and as a result of high saturation magnetization (25.51 emu/g), the spent material was easily separated upon application of a magnetic field. Meanwhile, the photogenerated holes (h+) and superoxide ions (O2-) were confirmed as the main active species. This novel photocatalyst is expected to provide a new insight into the design of photocatalysts with excellent recyclability, high performance, and good stability.