Study On The Properties Of Barium-based Apatite-structured Luminescent Materials And AgIO₃-based Photocatalytic Materials

LED（Light Emitting Diodes）, a kind of Light Emitting diode, is recognized as a kind of lighting materials for energy conservation and environmental protection due to long life, energy saving, safety, rich color, outstanding performance. Phosphors, the luminescent materials- in the LED, have been extensive researched. In this article, we prepare three kinds of apatite structured phosphor matrix materials Ba6K2La2（PO4）6F2, Ba6Na2Gd2（PO4）6F2 and Ba6K2Gd2（PO4）6F2,, and Eu²⁺, Tb³⁺ rare earth elements are doped in these phosphors to study the fluorescence properties. The emitting color of Ba6Na2Gd2（PO4）6F2: Eu²⁺ is blue. With increasing the content of Eu3+ ions, the emitting color of Ba6Na2Gd2（PO4）6F2: Eu²⁺, Tb³⁺ would change from blue to green due to the energy transfer between Eu²⁺ and Tb³⁺. The emitting color of Ba6K2Gd2（PO4）6F2: Tb³⁺ is blue- green. With increasing the content of Eu3+ ions, the emitting color of Ba6K2Gd2（PO4）6F2: Tb³⁺, Eu3+ would change from blue to red due to the energy transfer between Tb³⁺ and Eu3+. With increasing the content of Eu3+ ions, the emitting color of Ba6K2La2（PO4）6F2:Tb³⁺ would change from blue to green due to the two kinds of electron transition of 5D3 â†' 7FJ and 5D4 â†' 7FJ.Photocatalysts which shows a strong ability in terms of energy circulation, environmental treatment have caused wide public concern. This work studied a new type of silver containing photocatalyst AgIO₃.But because the band gap of AgIO₃（3.2 eV） is too large, it cannot absorb visible light. In order to enhance visible light absorption of AgIO₃, we prepare the two composite photocatalysts Ag/AgX（X = C l, Br, I）/AgIO₃ and Bi7O9I3/AgI/AgIO₃, and studied their photocatalytic activity and mechanism in photodegrading diverse liquid/gas phase pollutants. For Ag/AgX（X = Cl, Br, I）/AgIO₃ composite photocatalysts, their visible light absorption and photocatalytic activity are greatly enhanced compared with AgIO₃ precursor. In addition, these three series composite photocatalysts exhibit different photocatalytic mechanisms, which provide the reference for later papers in explaining photocatalytic mechanism. For Bi7O9I3/AgI/AgIO₃ composite photocatalysts, we prepare composition-adjustable polynary heterojunction photocatalysts via controlling the ratio of raw materials. When the KI/AgIO₃ molar ratio is 35%, 50%and 65%, the as-obtained samples are composed of AgI and AgIO₃. When the KI/AgIO₃ molar ratio is 5%, 10% and 20%, the as-obtained samples are composed of Bi7O9I3, AgI and AgIO₃. When the KI/AgIO₃ molar ratio is 80% and 100%, the as-obtained samples are composed of Bi7O9I3 and AgI. The visible light absorption and photocatalytic activity of composite photocatalysts are greatly enhanced compared with AgIO₃ precursor. AgIO₃@65% can effectively photodegrade MO, Rhodamine B, phenol, 2,4-Dichlorophenol, bisphenol A, and tetracycline hydrochloride. Moreover, the photocatalytic mechanism of the three groups photocatalysts with different composite are different.