纳米贵金属与光子晶体结构对基于上转换发光的红外光催化体系效率的提高

The efficiency of infrared photocatalysis driven by the upconversion emission from rare earth ions, depends on both the quantum efficiency of photocatalyst and the efficiency of upconversion. Therefore, we plan to introduce nano noble metal and photonic crystal into these systems, where light inducing charge carrier separation process can be promoted by the electronic storage effect of nano noble metals; upconversion emission can be enhanced by both the surface plasmon resonance resulting from the nano noble metal and the increasing of the state density near the edges of photonic bandgap, in condition of overlapping the upconversion spectra; the absorption of photocatalysts can be enhanced by the slow photon and the light scattering effects. The combination of these effects mentioned above can be multiplied on the final infrared photocatalysis efficiency. As a infrared photocatalytic system, the inverse opal structure with ordered porous takes the advantages of easy depositing nano noble metals and adhering semiconductors on the porous wall. It is suitable for rare earth ion doped molybdate, vanadate and tungstate,such as Bi2WO6:Yb,Tm@Ag. It can also be applied to rare earth ion doped fluoride, such as NaYF4:Yb,Tm@Ag/TiO2 for infrared photocatalysis. So this project not only solve the combination of rare earth ions, nano noble metals and photocatalysts, but also provides multi modulations on light emitting and photocatalytic processes where special properties will present in various component combination conditions.

以稀土离子的上转换发射来驱动光催化剂的红外光催化体系，其催化效率既取决于光催化剂的量子效率，又取决于上转换的发光效率。为此拟在该体系中引入纳米贵金属与光子晶体结构，通过纳米贵金属的电子蓄池作用促进光催化剂的电子空穴分离；利用等离子体共振效应增强上转换发光；利用光子晶体带隙边缘的态密度增加，增强上转换发射；通过带隙边缘慢光效应促进催化剂对光的吸收，上述因素的综合作用可达成多重倍增红外光催化性能的效果。有序大孔反蛋白石结构红外光催化体系，具有在孔壁沉积纳米贵金属与复合半导体的技术优势，适用于Bi2WO6:Yb,Tm@Ag等稀土掺杂钨酸盐、钼酸盐、钒酸盐多种体系，也适用于NaYF4:Yb,Tm@Ag/TiO2等稀土掺杂氟化物复合红外光催化体系，由此不仅解决了稀土掺杂离子、纳米贵金属、光催化剂三者的结构复合问题，而且能使处于多重调控下的发光与光催化过程，在多样化的组份体系中体现出特定的变化规律。

以稀土离子的上转换发射来驱动光催化剂的红外光催化体系，其催化效率既取决于光催化剂的量子效率，又取决于上转换的发光效率。同时，稀土掺杂离子、纳米贵金属、光催化剂三者的结构复合问题，也是相关驱动机理，获得近红外光催化效果的关键因素。为此，项目执行中以光子带隙调控上转换发光过程；基于上转换机制驱动的红外光催化；氮化碳与铋系光催化剂复合改性及红外光催化，为主要研究内容，并涵盖了纳米贵金属对光催化过程的电子蓄池作用和对上转换过程的等离子体共振效应的研究。. 在稀土掺杂氟化物与氧化物反蛋白石结构中，通过调控激发态过程，达成了光子带隙对上转换的颜色选择；在共掺杂体系中实现给体与受体离子之间的角色互换与能量再分配；利用带隙的中心与边缘效应同时达成了上转换不同颜色发射的抑制与增强效果。利用Ag/BaTiO3:Yb3+, Er3+反蛋白石结构实现光子带隙对不同颜色上转换发光的选择性抑制与增强，同时实现等离子体共振效应则对所有色系上转换的增强效果。得出：光子带隙对上转换发光过程的调控，本质上是激发态体系的能量再分配的问题，微观上表现为的各个能级电子布局的再分配，宏观上表现为不同上转换色系的选择性抑制与增强。. 对稀土掺杂氟化物/光催化剂、稀土掺杂氧化物光催化剂的研究验证了上转换驱动光催化剂的机理：①上转换光再吸收；②激活离子与催化剂基质能量传递。在CQD/Bi2WO6: Yb3+, Er3+体系中利用碳量子点的宽带上转换发射驱动Bi2WO6光催化剂，实现了普通非相干宽激发红外光催化。在Ag/Bi2WO6:Yb3+,Er3+中，纳米银提高了光催化效率，表现出等离体共振效应与能量传递过程的关联性。在Bi2O2CO3/Bi2WO6：Yb3+, Er3+中获得了较好的红外光催化效果，在Bi2MoO6/BiOF:Yb3+,Tm3+体系中，获得了超过已报道的最高红外光催化效率。. 以成本低廉工艺简单的活性炭改性三聚氰胺，制成了高性能富碳类石墨相氮化碳光催化剂。制备的Bi2O2CO3/g-C3N4二元复合体系、AgBr/BiOBr/g-C3N4三元复合体系均达到对g-C3N4的明显改性效果。制备的MnOx/g-C3N4催化剂表现出显著的光热协同催化效果。