Gd-BiVO₄ photocatalyst for organic contaminants removal: Short-term synthesis at sub-100 °C and enhanced sunlight-driven photocatalytic activity

A novel and short-term preparation method was conducted to fabricate pristine BiVO_4, and Gadolinium (Gd) doped BiVO₄ photocatalysts at sub-100 °C. The optical, structural, morphology, microstructure, and compositional characteristics of the fabricated photocatalysts were examined, which illustrated that the doping of Gd stabilized the existence of the tetragonal phase structure and enlarged the specific surface area of the pristine BiVO₄. The comparison of the photocatalytic performance, preparation power consumption, and preparation cost showed the superiority of Gd doped BiVO₄ photocatalyst fabricated by the Short-Term Synthesis Method at sub-100 °C. The ofloxacin (OFL) removal rate with 5%, 7%, and 10% Gd-BiVO₄ photocatalysts was 1.53, 1.61, and 1.83 times that with pristine BiVO₄ under sunlight, respectively. The degradation performance of target contaminants, including diclofenac, tetracycline HCl, ofloxacin, rhodamine B, and sulfadiazine, was demonstrated after one hour of sunlight irradiation with 5% Gd-BiVO₄, achieving the removal efficiencies of 98.63%, 98.07%, 97.98%, 92.09%, and 78.56%, respectively. The effect of various factors on the removal performance was revealed, indicating that SO₄²⁻ and H₂PO₄⁻ had a remarkable inhibitory effect on the degradation. The 5% Gd-BiVO₄ also showed excellent reusability and stability after five-cycle runs. The photogenerated holes (h⁺) and the superoxide radicals (^•O₂⁻) were the predominant generated active species, and the possible photocatalytic mechanism for the degradation of organic contaminants was proposed. Simple prepared Gd-BiVO₄ photocatalysts were revealed to be a practical and potential choice for efficiently degrading contaminants with sunlight as green energy.