面向含水环境应用的ABF4基分层化合物的合成化学及高效能量转化研究

The overlapping of absorption spectra between commonly used sensitizer Yb3+ and water molecules in the near infrared region results in a profound loss of energy, which would constrain the applications of many photo-functioned materials in energy conversion and environmental applications, especially in water containing condition. Based on the literature reports and our previous studies, we proposed to construct ABF4-based multi-layer structures in consideration of the interfacial stress regulation and synergistic sensitization of Nd3+-Yb3+, could highly possible to realize single band up-conversion emission with 808nm excitation, and further to significantly reduce the thermal effect caused by near-infrared light. Motivated by this, in this project, we will prepare Nd3+ -Yb3+ co-sensitized up-conversion materials firstly, and then aim to synthesize Er3+ /Tm3+/Ho3+ doped ABF4-MOx multi-layer composites. We will study the effect of Nd3+-Yb3+ co-sensitization, non-intrinsic level construction, modulation of lattice stress in band gap width of MOx as well as lattice symmetry of each component. We expect to utilize the near infrared light, that traditional photo-function materials could not be excited, to broaden the light response range. Moreover, the realization of full spectral response from UV, visible to near infrared lights can increase the detection depth of up-conversion fluorescence, and help us develop new ways to suppress the thermal effect of infrared light in watery photochemical reaction. We believe that these achievements could lead to new materials of high performance for further applications in energy conversion and environmental fields.

常用敏化剂Yb3+与水分子在近红外区存在光吸收重叠，造成严重能量损失，制约许多光功能材料在能源及环境等含水环境的应用。在文献调研和前期研究基础上，我们设想把ABF4基化合物的分层构筑，界面应力调控和Nd3+-Yb3+协同敏化相结合，获得808 nm激发单波段发射的稀土上转换发光材料，降低近红外光引起的热效应和能量损失。为此，本项目拟通过Er3+/Tm3+/Ho3+分层掺杂ABF4的合成，Nd3+-Yb3+协同敏化，非本征能级构建、晶格应力调变带隙宽度和晶格对称性等方式，合成Nd3+-Yb3+协同敏化上转换材料-半导体复合材料；利用传统光功能材料无法利用的近红外光，拓宽其在近红外区的响应范围，在提高上转换荧光探测深度的同时，实现紫外-可见-近红外光区全光谱响应，探索抑制红外光在水反应体系中热效应的新途径，实现面向含水环境光化学反应中的高效能量转化，为未来能源及环境等领域应用提供高性能新材料。

高效光功能材料的发展仍面临着挑战, 而耐水性和稳定性是制约光功能材料发展的关键因素。通过引入多级分层的复合结构，改变光功能材料的空间构型、化学组成和表界面离子化学键性，调变材料的结构和电子跃迁行为，可望搭建高效能量(电子)传递的桥梁，实现紫外-可见-近红外光区全光谱响应，获得在含水环境可促进光化学反应进行的高性能光功能材料。..本项目开展了面向含水环境应用的多级分层化合物的合成化学及高效能量转化研究。获得了NaGdF4:Yb/Eu@NaGdF4:Ce@NaGdF4:Yb/Tb@ NaYF4多层核壳结构等荧光材料；合成了具有高催化活性的亚稳态CaCl2型TiO2与金红石相TiO2共生的同质异结构复合物；制备了具有特殊P-Sn界面键的SnO2/g- C3N4、NaBiF4/Yb3+,Tm3+/Er3+@TiO2等多级分层复合材料。全面考察多级分层复合材料的晶体结构、纳米结构、缺陷结构、晶格应力等因素及作用。在多级分层结构中，搭建了从内部不同稀土离子间有效能量传递，到外部不同组分之间界面间的高效电子转移的桥梁。通过研究，我们对具有单分散特征的纳米晶以及从单分散纳米晶出发获得多级分层复合材料的制备化学，微结构构筑、表界面缺陷态控制、组分单元相互作用、电子转移和有效能量传递等相关科学问题有了系统的认识，揭示了多级复合结构中组分单元组分，界面键化学属性的变化对能量传递、电荷传输的影响，并且对多级复合结构的构筑化学机理-稳定性-高效能量(电子)传递-光激发下化学与物理性能的内在关系有了初步的了解, 获得了紫外-可见-近红外光区光谱响应材料，并在水环境中，利用红外光激发实现了光催化反应。同时在国内外重要学术刊物上系统发表论文30余篇，有1项发明专利在项目执行期间获得授权，同时新申请国家发明专利5项；有从事光物理和光化学研究的5名博士生和1名硕士生在项目执行期间毕业，还有多名将在未来2-3年完成学业。顺利完成了项目的目标。