二维单分子层状前过渡金属复合氧化物材料的可控制备、构筑与光催化性能

The proposal aims to develop early transition metal complex oxides 2D nanosheet materials with high photocatalytic performances. A controllable and rapid method will be explored and established for the preparation of the 2D nanosheet materials with the single molecular layer thickness, based on both the down-up and up-down routes. The novel composite nanosheets with ultra-thin surface junctions will be constructed and assembled by using the difference of the nanosheets in surface properties. The redox potential of the conduction and valence band would be modulated to match the energy level of the reactant molecules with changing band structure of composite nanosheets. Furthermore, the prepared methods and assembly rules will be summarized. The effects of 2D nanosheet composite on photoctalytic performances will be investigated in detail, including their components, crystal structures, electronic structures, ultra-thin surface junctions and photogenerated charge behaviors. Combined with quantum chemical calculation, we will unravel the interaction relationships between the cocatalysts and 2D nanosheets， and the inherent relationships between structure and photocatalytic activities of the composite nanosheets. Meanwhile, a probable photocatlytic mechanism of early transition metal composite oxides with monolayer 2D nanosheets morphology will be clarified for hydrogen production from water and selectively organic synthesis. Finally, we are expected to establish a possible theory for the guidance of designing photocatalytic materials with high quantum efficiency on a molecular level.

本课题以发展高效稳定的前过渡金属复合氧化物的单分子层二维纳米片光催化材料为研究目标。探索和建立快速的自下而上或自上而下的制备单分子层二维纳米片的新方法；利用纳米片材料的表面性质差异构筑组装具有超薄表面结的新颖复合材料，调变其能带结构，使之导带和价带的电势分别与反应物分子的能级相匹配，总结这类光催化材料的制备和构筑组装规律；探索其组成、电子结构、晶体结构、超薄表面结特性和载流子迁移行为及其对催化效应的影响。结合量子化学计算，揭示助催化剂材料与二维纳米片光催化材料之间的相互作用以及催化剂结构与活性之间的内在联系，阐明复合二维纳米片光催化材料在可见光分解水制氢和选择性有机合成中的作用机制，提出从分子水平指导设计高效光催化材料可能的理论。

本项目通过选择合适的过渡金属复合氧化物光催化材料，运用晶体工程和超分子化学原理，可控制备了系列具有高比表面积、稳定的二维过渡金属复合氧化物纳米片，如HNbxTa1-xWO6，H1.07Ti1.73O4，H1.4Ti1.65O4H2O，Bi2MoO6，Au-Pd/MgAl-LDH，HNb3O8 ，HSr2Nb3O10，HTi2NbO7，BiOCl，ZnTi-LDH。此外，利用纳米片的大比表面积，丰富的表面不饱和活性位点等特点，构筑了系列二维单分子层纳米片基新型复合光催化材料，如Pd/H1.07Ti1.73O4, CdS/HCa2Nb3O10，Pd /TiO2(B)，Pt/Sb2WO6, Au-Pd/MgAl-LDH, Pd/HNb3O8, Pt/HTi2NbO7, MO/TiO2, AuPt/H1.07Ti1.73O4, Cu2O-Cu/H1.4Ti1.65O4H2O。它们在光催化反应中如产氢、有机物选择性合成等表现出较高的光催化活性和催化活性稳定性。进一步深入探讨了二维单分子层纳米片的组成、电子结构、超薄表面特性和载流子迁移行为及其对光催化反应的影响。结合量子化学计算，揭示了纳米片与助催化剂之间的协同机制，提出指导设计具有高效光催化性能的二维纳米片复合光催化剂的可能理论。这些结果将对纳米片基光催化剂的制备、能带调控以及从分子水平认识光催化作用奠定理论和实验基础。