太阳光驱动上转换发光碳点/TiO2纳米晶体/TiO2光子晶体叠层复合膜光催化剂深度处理难降解煤化工有机废水

A novel tandem carbon dot/TiO2-nc/TiO2-PC (t-CDs/TiO2-nc/TiO2-PC) composite film photocatalyst alternatively stacked by functional photocatlaytic units (nx) constructed by TiO2 photonic crystal and upconversion luminescent carbon dot/TiO2 nanocrystal in order is proposed for full-spectrum solar-light-driven photocatlaytic degradation of refractory organic pollutants in industrial wastewater. In each functional photocatlaytic unit, the photonic crystal reflects light of certain wavelengths falling in its photonic band gap, the carbon dot upconverts the reflected light to UV-light, TiO2 absorbs the UV-light and photocatalytic degrades organic pollutants. The absorption spectrum of the functional photocatlaytic unit is determined by the position of photonic band gap and the excitation spectrum of carbon dot. In principle, tandem construction with alternatively stacked functional photocatalytic units with different absorption spectra can utilize the full-spectrum solar-light. The key point of the proposal is to adjust and controllably assemble stale tandem film photocatalysts with optical performance matched constituent components. Based on the t-CDs/TiO2-nc/TiO2-PC film photocatalysts, the relations between catalyst structure-light absorption property-photocatalytic property will be explored systematically. An efficient photocatalytic reactor based on the tandem film photocatalyst will be designed and a small-size demonstration system for continuous wasterwater treatment will be established and applied for advanced treatment of real industrial wastewater under natural solar light irradiation. The structural extention of the tandem composite film photocatalyst is very rich, which would pave a new way to further develop practical photocatalytic techniques with high efficiency.

本项目提出一种吸收全光谱太阳光的新型碳点/纳米TiO2/TiO2光子晶体叠层复合膜光催化剂，由TiO2光子晶体和上转换发光碳点/纳米TiO2组成的功能催化单元(nx)按一定顺序层层叠加组装而成。每一个功能单元中的光子晶体通过其“光子禁带”作用选择性地反射特定波长的光，碳点则将反射光上转换为紫外光，TiO2吸收紫外光催化降解有机污染物。功能单元的吸光范围由“光子禁带”的位置和碳点的激发光谱确定。原理上，吸光范围不同的功能单元按一定顺序层层叠加，即可高效吸收全光谱太阳光。项目重点调控和组装结构组元光学性能匹配的稳定叠层光催化剂，深入研究催化剂结构与吸光性能和催化性能之间的构效关系。设计开发基于叠层光催化剂的高性能光催化反应器，搭建连续运行的小型光催化废水处理示范系统，实现太阳光驱动光催化高效深度处理工业废水。叠层光催化剂的结构外延丰富，可为开发太阳光驱动的实用高性能光催化技术开辟新的途径。

本项目围绕提出的一种吸收全光谱太阳光的新型碳点/纳米TiO2/TiO2光子晶体叠层复合膜光催化剂的制备、光学性能及光催化性能展开研究，建立了不同尺寸大小的PMMA单分散微球制备数据库，为进一步制备TiO2反蛋白石薄膜提供了扎实的基础;合成出宽光谱响应上转换发光材料（碳点及稀土掺杂氟乙酸钠纳米颗粒）；制备出高质量高稳定性PMMA叠层光子晶体薄膜，并获得了控制其结构有序性和稳定性的关键控制因素和条件；PMMA叠层光子晶体薄膜与上转换发光材料氟乙酸钠复合，荧光发光光谱证明了叠层光子晶体与上转换发光材料协同显著调控薄膜光学性能的作用，提出两种作用机制；制备出碳点/TiO2nm纳米颗粒/TiO2反蛋白石薄膜，光催化降解苯酚显示出光子晶体结构与上转换发光材料协同作用提升了光催化性能。同时，利用研究中发现的新的合成机制，采用高温刻蚀、光化学活化等方法调控g-C3N4、Co3O4等非贵金属催化剂中的氮空位和氧空位的结构和数量，显著提高了该类材料的光解水和光催化CO2还原制合成气的催化性能，空位结构对光催化剂能带结构、反应物及中间产物的吸附和解离产生重要的调控作用，是光催化性提升的重要原因。此外，将本项目合成的碳基纳米材料与MoS2-Ti4O7复合，发现碳纳米结构能够调控催化剂结构，改善催化剂的晶体尺寸和相结构，向MoS2基面引入更多的缺陷，从而提高电解水析氢活性和稳定性。这些研究结果对开发以非贵金属材料为基础的高性能光、电催化材料的研究提供了丰富的新视角，有关叠层光子晶体催化剂的研究有望进一步发展形成光催化废水处理技术。