Ultraviolet-C (UVC) light shows important application prospects in disinfection, disease phototherapy, cancer photodynamic therapy, etc. Here, a novel UVC upconversion phosphor δ -Y 2 Si 2 O 7 :Pr 3+ with excellent optical properties was successfully prepared by the high-temperature solid-state reaction method and the sol-gel method. The XRD results clarified the law of phase transition from the β -/ γ -Y 2 Si 2 O 7 to the δ -Y 2 Si 2 O 7 phase. The diffuse reflection spectra of phosphors prepared by two different methods exhibited two obvious absorption bands related to the 3 H 4 → 3 P 2 and 3 H 4 → 1 D 2 transitions of Pr 3+ ions. And the values of the band gap were estimated by diffuse reflection spectra, which are in good agreement with the value calculated by DFT . Under the excitation of 460 nm laser, two emission peaks corresponding to the 4 f 5 d → 3 H 4 and 4 f 5 d → 3 H 5 transitions of Pr 3+ ions were discovered at ∼247 nm and ∼258 nm in the range of 230–280 nm. Additionally, the phosphor prepared by the sol-gel method has a higher emission intensity than the phosphor prepared by the high-temperature solid-state reaction method. With the help of temperature-dependent emission spectra , the phosphor prepared by two methods demonstrated outstanding thermal stability up to 150 °C, and the luminescent intensity at 150 °C remained 86.8% and 87.9% of that at ambient temperature, respectively. The results mentioned above suggest that the Y 2 Si 2 O 7 :Pr 3+ phosphor may have potential applications in the field of disinfection.
Far ultraviolet-C (far-UVC; 200–230 nm) luminescent materials have garnered significant interest in recent years, driven by the growing demands for applications such as disinfection and solar-blind imaging due to their distinct wavelength features. However, the research and development of far-UVC persistent phosphors are lacking. Here, we report the realization of far-UVC persistent luminescence in CaSO4:Pr3+ and CaSO4:Pb2+ phosphors, which show emissions peaking at 220 nm and 230 nm with a long persistence time of >24 h after ceasing X-ray excitation. This is by far the shortest UVC afterglow emission to the best of our knowledge. The far-UVC afterglow from the charged phosphors can be readily detected by a solar-blind UV camera in both indoor-lighting and outdoor environments owing to the absence of background noise from ambient light. The continuous photostimulation of indoor white LED light and outdoor sunlight has different impact on the far-UVC afterglow performance of CaSO4:Pr3+ and CaSO4:Pb2+ phosphors, which is elucidated by the decay time-dependent thermoluminescence (TL) curves in different light conditions. This study expands the field of persistent luminescence to the far-UVC spectral region and will inspire the discovery of more excellent far-UVC persistent phosphors.
Low-molecular-weight organic pollutants present in feed water pose a significant challenge to maintaining ultrapure water (UPW) quality, as they are not readily removed by conventional treatment processes. Urea is a low-molecular-weight, nonionic, persistent organic pollutant resistant to conventional UPW production processes. Therefore, suitable oxidation technologies must be explored to convert urea to inorganic nitrogen ions, which are more easily removed in post-UPW treatment steps. In this study, the far-UVC (peak wavelength centered at 222 nm) coupled persulfate (PS) activation system was used for the effective oxidation of urea to nitrate (NO 3 − ). In the degradation of urea (10 μM, PS 0.4 mM, pH 7), far-UVC/PS systems (k urea,222/ PDS= 1.69 × 10 −3 cm 2 ∙mJ −1 , k urea,222/PMS = 2.69 ×10 −4 cm 2 ∙mJ −1 ) were found to be superior to conventional 254 nm LPUV/PS systems (k urea,254/PDS = 1.07 ×10 −4 cm 2 ∙mJ −1 , k urea,254/PMS = 7.01 ×10 −5 cm 2 ∙mJ −1 ). The far-UVC/PDS system showed the highest efficiency, achieving complete urea removal after 5241.0 mJ∙cm −2 of irradiation. The dominant role of SO 4 •− in urea degradation was systematically investigated, with urea removal showing a strong correlation with the steady-state concentration of SO 4 •− . Moreover, the evolution of inorganic nitrogen species and the reduction of total organic carbon were examined to assess the applicability of the system as a pretreatment technology in UPW production. The results provide valuable insights into the integration of the far-UVC process for the removal of low-molecular weight pollutants during UPW production.
危险品化学品经营许可证（带存储）