宽光谱吸收钛铌基纳米片/金属催化剂的构建及其光热协同选择性氧化性能

Selective oxidation of aromatic alcohols to aldehydes is of fundamental importance in both basic research and fine chemical production. Solar-driven photo-thermal catalysis is considered as an ideal green approach for the oxidation of aromatic alcohols. The key for its application is the development of high-performance catalyst. However, the currently developed catalysts generally suffer from limited light absorption, poor catalytic activity, and unclear reaction mechanism, which hinder the development of the technology. In this proposal, we aim to design and fabricate novel synergistic heterostructured catalyst with wide-spectrum solar absorption through the integration of photoactive two-dimensional ultrathin Ti,Nb-based nanosheets with thermal active metal component. The light absorption and catalytic active sites of the as-prepared photo-thermal-catalysts will be regulated by tuning the microstructures, including the constitute and defect site of the nanosheets, as well as the size and exposed crystal facet of the metal, thereby realizing the efficient selective oxidation of the aromatic alcohols. In addition, taking the advantage of the well-defined surface structure of the 2D nanosheets and the precise structure control of the metal unit, the composition-structure-performance relationship of the catalyst will be studied. Moreover, the photoinduced charge separation and migration behavior of the catalysts, and the transformation of reactant molecules on the catalysts surface under the photo-thermal coupling fields will also be investigated. In combining with the theoretical calculation, the synergistically photo-thermal catalytic mechanism will be studied to establish a reaction model. The research is expected to provide experimental basis and theoretical support for the development of new solar-powered photo-thermal-catalysts for efficient and selective oxidation of alcohols.

芳香醇选择性氧化产醛工艺在基础研究领域和精细化工生产中均占有重要地位。太阳能驱动光热协同催化技术是实现芳香醇绿色氧化的理想途径，实现其应用的关键在于高效催化剂的研发。本项目针对当前光热协同催化剂存在的光吸收范围窄、催化活性低和光热协同机制不明等问题，拟以二维超薄钛铌基纳米片为光活性组成基元，集成金属热活性组分，构建新型宽光谱吸收异质结构催化剂。从微观结构 (纳米片组成、缺陷位，金属尺寸、暴露晶面等) 入手调控催化剂的光吸收性质和催化活性位点，实现芳香醇的高效选择性氧化。同时，基于超薄纳米片结构的明确性以及金属单元的可精准调控性，考察催化剂组成-结构-性能之间的关系；研究光、热场耦合下，催化剂的光生电荷分离迁移，芳香醇分子在催化剂表面的反应过程，结合理论计算，阐明光热协同催化作用机制，建立反应模型。本研究成果可为发展新型光热协同催化剂实现醇的高效选择性氧化提供实验基础和理论支撑。

太阳能驱动光热协同催化兼具经济和环境效益，是实现芳香醇绿色氧化的有效途径。针对传统光热协同催化剂光吸收范围窄、催化活性低和光热协同机制不明等问题，本项目基于二维超薄材料独特的理化性质和清晰的表面结构等优势，集成金属活性组分，发展了系列新型宽光谱吸收光热协同催化剂，并围绕催化剂的构-效关系及反应机理开展了深入研究。项目取得的主要研究结果如下：(i) 发展了一类光照下金属催化还原氧化物纳米片制备缺陷的策略，实现了在低温、无外加还原剂的温和条件下可控地引入缺陷，构建了系列具有宽光谱吸收的Pd/H2Ti6O13、Pt/H2Ti6O13、Pt/HNb3O8二维纳米片/金属光热协同异质结催化剂。（ii）揭示了氧缺陷的引入可以促进催化剂表面Lewis酸位点的暴露，提供大量反应活性位点，促进芳香醇的吸附和活化；同时氧缺陷拓展了复合材料的光吸收范围，实现了分级分质利用太阳能同步光激发和热转换，热效应促进了光生载流子进一步的有效分离和迁移、提高了催化剂与反应物分子苯甲醇的接触机率，进而获得了高效的光热协同氧化芳香醇性能，提高了太阳能的利用效率。(iii) 开发了光热协同无氧氧化芳香醇至醛并产氢的反应新途径。该过程直接利用光生空穴氧化芳香醇选择性脱氢，并利用光生电子将脱掉的氢还原为氢气，既避免了芳香醛产物被进一步氧化为酸，又避免了脱除的氢被氧化变为副产物水，提高了芳香醇氧化反应的选择性和原子经济性。.总之，在项目执行期间，我们获得了较多有价值的研究成果，发表与本项目相关的SCI论文12篇、EI论文2篇，申请国家发明专利2项。