Electronic properties and photodegradation ability of Nd-TiO2 for phenol

In this study, the photocatalytic activity of Nd-TiO₂ photocatalysts obtained by common hydrothermal method was evaluated by practical experiments and theoretical calculations based on density functional theory (DFT). The synthesized photocatalysts were characterized by X-ray diffraction (XRD), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) to study their physical/chemical properties. At the same time, the photoelectronic performance was also investigated. The photodegradation ability of as-prepared photocatalysts and the effect of Nd doped amount and photocatalysts dosage were investigated by the photodegradation of phenol (30 mg/L) under 400 W metal halide lamp (UV–Vis). The effect of Nd on electronic properties of TiO₂ and adsorption ability of phenol were discussed. Results show the red-shift wavelength of 0.5 mol%Nd-TiO₂, indicating that its absorption capacity is stronger than pristine TiO₂ in the same wavelength range. The result of DFT calculations demonstrates that the optical bandgap of Nd-TiO₂ is profoundly reduced, thus the light absorption ability is promoted, which will be responsible for the enhanced photocatalytic performance of Nd-TiO₂. 0.5 mol% Nd is an optimum value for photodegradation phenol, and phenol can be completely degraded by 0.5 mol%Nd-TiO₂ for 210 min, the higher catalytic performance is derived from the efficient separation of e^–/h⁺ pairs. Moreover, the adsorption energy calculations of phenol on TiO₂ (101) and Nd-TiO₂ (101) demonstrate that the Nd doping can significantly enhance the adsorption ability of phenol on catalyst surfaces because of the formation of Nd–O bonds. At last, the stability measurement through four recycles exhibits that 0.5 mol%Nd-TiO₂ possesses excellent stability.