The CeO 2 -TiO 2 (CeTi) and CeO 2 /WO 3 -TiO 2 (CeWTi) catalysts were prepared by sol-gel method. The as-prepared catalysts were hydrothermally treated at 760 °C for 48 h in air containing 10 vol% H 2 O to obtain the hydrothermal aged catalysts. The sulfur aged catalysts were treated at 400 °C with 100 ppm SO 2 , 10% water vapor, air balance for 48 h and catalysts. The powder X-ray diffraction (XRD) and Raman results indicate that the crystallization of hydrothermal aged catalysts is more serious than sulfur aged catalysts. In addition, tungsten species can stabilize the CeTi catalyst from grain growth. According to the results of in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS), temperature-programmed desorption of ammonia (NH 3 -TPD), H 2 temperature-programmed reduction (H 2 -TPR) and ammonia oxidation , the aging process leads to loss of surface area, redox properties, surface acidities and surface ceria concentration, especially for the hydrothermal aging. The NH 3 -NO/NO 2 SCR performances of sulfur aged catalysts are better than that of hydrothermal aged catalysts. Compared with CeTi catalyst, the addition of tungsten inhibits the crystallization of catalyst. So that more acid sites and active sites are retained. This is also the reason why tungsten addition improves the NH 3 -NO/NO 2 SCR performance of CeTi catalyst.
(Sr, Ca)AlSiN 3 :Eu 2+ (SCASN) phosphors are widely used in white LEDs due to their excellent red spectral performance. However, exposure to high temperature, high humidity, and sulfur-containing environments significantly degrades their performance and long-term stability. Herein, a rapid plasma-assisted deposition technique is employed to apply an ultrathin Si-based nanolayer onto SCASN (SCASN-Coated), enhancing its durability under such harsh conditions. Accelerated aging tests conducted at 100 °C, 100 % relative humidity (RH), and in a sulfur-containing atmosphere reveal that unmodified SCASN retains only 24.1 % of its initial luminous intensity after 1008 h, whereas the SCASN-Coated preserves approximately 41.2 % of their original brightness without compromising intrinsic luminescent properties. First-principles calculations and molecular dynamics simulations further elucidate that SCASN has a strong chemical adsorption effect on SO 2 (−3.056 eV). And the combined presence of SO 2 and H 2 O promotes the displacement of Ca 2+ ions, accelerating degradation. The protective SiO 2 nanolayer drastically reduces the SO 2 adsorption energy (−0.124 eV) and inhibits Ca 2+ ion migration. This surface protection strategy not only augments the resilience of SCASN phosphors under extreme conditions but also provides research paradigm into the degradation mechanisms, thereby offering new avenues for extending the service life of LED devices in challenging environments.
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