Shouqiang Huang,Zhichun Li,Bo Wang,Nanwen Zhu,Congyang Zhang,Long Kong,Qi Zhang,Aidang Shan,Liang Li
Under illumination of light-emitting diode (LED) or sunlight, the green color of all-inorganic CsPbBr3 perovskite nanocrystals (CPB-NCs) often quickly changes to yellow, followed by large photoluminescence (PL) loss. To figure out what is happening on CPB-NCs during the color change process, the morphology, structure, and PL evolutions are systematically investigated by varying the influence factors of illumination, moisture, oxygen, and temperature. We find that the yellow color is mainly originated from the large CPB crystals formed in the illumination process. With maximized isolation of oxygen for the sandwiched film or the uncovered film stored in nitrogen, the color change can be dramatically slowed down whether there is water vapor or not. Under dark condition, the PL emissions are not significantly influenced by the varied relative humidity (RH) levels and temperatures up to 60 °C. Under the precondition of oxygen or air, color change and PL loss become more obvious when increasing the illumination power or RH level, and the large-sized cubic CPB crystals are further evolved into the oval-shaped crystals. We confirm that oxygen is the crucial factor to drive the color change, which has the strong synergistic effect with the illumination and moisture for the degradation of the CPB film. Meanwhile, the surface decomposition and the increased charge trap states occurred in the formed large CPB crystals play important roles for the PL loss.
Huajian Ou,Lu Chen,Qiaohui Zeng,Zhiyun Peng,Zihao Lin,Ping Qi,Konglong Feng,Jing Jing Wang
A 5-aminolevulinic acid (ALA)-grafted chitin film (O-CT/ALA film) with a photodynamic inactivation (PDI) against bacteria was previously fabricated, and its preservation efficiency and mechanisms against salmon were explored. Results showed that the PDI-mediated O-CT/ALA film exhibited sustained generation capability of ROS, which had potent antibacterial activity in vitro under blue LED irradiation. Moreover, this film significantly inactivated the native bacteria and suppressed their growth in salmon fillets during storage at 4 °C and 25 °C, extending the shelf-life by >2 days compared to commercial polyethylene film. Consequently, the O-CT/ALA film retained the textural integrity of salmon muscle, stabilized the physicochemical properties of pH value, electrical conductivity, color appearance, and reduced the level of protein and lipid oxidation. Notably, it obviously reduced the accumulation of microbial metabolites and oxidation-related volatile compounds in salmon. Therefore, the PDI-mediated film shows a valid ability in preserving the storage quality of aquatic products.
危险品化学品经营许可证（带存储）