A facile one-pot synthesis of gadolinium doped TiO₂-based nanosheets with efficient visible light-driven photocatalytic performance

Gadolinium doped TiO₂-based nanosheets (Gd-TNSs) with different Gd/Ti ratios are prepared by a facile one-pot hydrothermal method using gadolinium nitrate as the gadolinium precursor. The photocatalysts are characterized by high-resolution transmission electron microscopy (HRTEM), Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible light diffuse reflectance spectra (DRS), fluorescence spectra (FL), and N₂ adsorption–desorption measurement. The as-synthesized samples show clearly sheet-like structure, with the width of about 30–100 nm, length greater than 100 nm, and high specific surface area (200–300 m²/g). The patterns of XRD and Raman analyses indicate that doped gadolinium has obvious influence on the structure of samples. The band-gap energy (E _g) of photocatalysts reduce from 3.17 to 3.02 eV with the content of gadolinium increasing from 0.1 to 1.5 at. %. The FL emission intensity initially decreases with the content of Gd increasing and then increases after minimizing at 0.5 %-Gd-TNSs, which reveals that appropriate amount of gadolinium doping can effectively inhibit the recombination of photo-generated electrons and holes. The adsorption capacity and photocatalytic activity are evaluated by Rhodamine B (RhB). The best photocatalytic performance is obtained when the doping ratio of gadolinium is 0.5 at. %. The visible reaction rate (K _app) of 0.5 %-Gd-TNSs was 2.0-fold as compared to TNSs, and 4.7-fold as compared to P25. The possible mechanisms for enhanced visible-light photocatalytic activities are discussed in detail.