Enhanced Photocatalytic Activity of Directly Assembled Fe₂O₃/Gd₂O₃@TiO₂-Based Nanosheets.

Abstract

TiO₂-based nanosheets (TNSs) modified with surface-enriched Fe₂O₃ and Gd₂O₃ nanoparticles (NPs) have been synthesized via a direct interfacial assembly strategy. The TNSs with a unique two-dimensional structure are favorable for supporting Fe₂O₃ and Gd₂O₃ NPs for photocatalytic applications. The prepared samples were characterized using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), BET, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectroscopy and the surface photocurrent (SPC) technique. The photocatalysts exhibited large specific surface area (160-260 m²/g). The co-modification with Fe₂O₃ and Gd₂O₃ NPs influenced the crystallinity and surface area of the TNSs, and improved visible-light absorption. Surface photocurrent and PL studies revealed that the photogenerated charge carrier separation efficiency could be improved by an appropriate amount of NPs. The optimized nanostructure exhibited photocatalytic efficiency for rhodamine B (RhB) degradation and H₂ production is 5.66-fold and 2.99-fold respectively than those of TNSs under visible-light irradiation. The enhancement is attributed to the combined effect of Gd₂O₃ and Fe₂O₃ NPs in the Fe₂O₃/Gd₂O₃@TNSs composites. The simultaneous use of two different types of NPs led to a fast separation and slow recombination of photoinduced electron-hole pairs. A mechanism is proposed to explain the enhanced visible-light photocatalytic activity.