Using praseodymium nitrate (III) hexahydrate (Pr(NO3)3·6H2O), ammonium metavanadate (NH4VO3) and hexadecyl trimethyl ammonium bromide (CTAB) as raw materials, PrVO4 samples were successfully prepared by hydrothermal method. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential scanning calorimetry (TG-DSC), UV–visible diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR). The effect of different synthesis temperature and illumination time on the ultraviolet photocatalytic activity of PrVO4 samples was studied with methyl orange solution as simulated sewage. The results show that the pure tetrahedral zircon structure of the PrVO4 sample can be obtained at a hydrothermal temperature of 100–180 °C. The sample of PrVO4 prepared by hydrothermal temperature at 140 °C was uniform, with an average particle diameter of 50–60 nm and a band gap width of 3.1 eV. The photocatalytic experiment demonstrates that the degradation rate of 100 mg/L methyl orange is nearly 92.4% in the presence of PrVO4 sample prepared at 140 °C after UV irradiation at 30 min. The PrVO4 samples show excellent photocatalytic performance for degradation of methyl orange.
Li Li,Zhimei Sun,Mai Xu,Jiewei Rong,Longde Wang,Yi Chen,Lujiang Wang,Fengwu Wang
Novel tetragonal PrVO 4 nanocubes have been fabricated by a simple and green hydrothermal method. The excellent catalytic activity of the samples was investigated for the degradation of methylene blue aqueous solution under visible light irradiation. As compared with pure PrVO 4 and H 2 O 2 , the photocatalytic efficiency of the PrVO 4 /H 2 O 2 system was enhanced about 1.5 and 9 folds, respectively. In the whole photocatalytic process, h + and ·OH radicals played the dominant roles on the basis of the trapping test. The significantly enhanced photocatalytic activity was attributed to the synergistic effect between photocatalytic oxidation of PrVO 4 and heterogeneous photo-Fenton-like reaction of V(V)/H 2 O 2 . Finally, a possible photocatalytic mechanism was proposed.
Gaoqing Hang,Qiulei Li,Alberto José Fernández-Carrión,Sihao Deng,Lunhua He,Xiaojun Kuang,Xiaoyan Yang
Oxide-ion conductors based on tetrahedral anion-related oxides have attracted considerable attention due to their high oxygen-ion conductivity and potential applications in clean energy devices, such as solid-state fuel cells. In this study, we report the improvement of oxide-ion conductivity by Sr2+ doping in isolated tetrahedral zircon-type PrVO4. It is found that Pr0.975Sr0.025VO4−δ features the highest oxide-ion conductivity of 2.62 × 10–3 S·cm–1 at 800 °C under air, with an oxygen transport number of 0.93. The formation and stabilization of oxygen vacancy defects, as well as the oxide-ion migration mechanism in PrVO4, were investigated through combining experimental characterizations and computing simulations. The results indicate that the concentration of oxygen vacancy defects increases with Sr2+ substitution, and the vacancies are accommodated by the formation of corner-sharing V2O7 dimers. Oxygen-ion migration proceeds via a cooperative mechanism involving V2O7-dimer breaking and reforming assisted by synergistic rotation and deformation of neighboring VO4 tetrahedra. The results provide valuable insights for further investigation and optimization of zircon-type oxides as potential oxide-ion conductors for electrochemical devices.
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