双位点铌酸盐超薄片光催化体系的构建及其还原CO2制备碳氢燃料研究

Hydrocarbon fuel production from photocatalytic CO2 reduction is an ideal way for the CO2 conversion and utilization. To address the low conversion efficiency issue of niobate (SnNb2O6 or KCa2Nb3O10) ultrathin nanosheet materials, this project proposes a new idea that the surface defect and PdCu alloy modifications can be simultaneously introduced into the niobate ultrathin nanosheets to construct a novel niobate ultrathin nanosheets-based photocatalytic system with dual active sites, which will be used in the photocatalytic CO2 reduction reaction towards the production of hydrocarbon fuels. The strategy and its law on the control of surface defect amount of ultrathin nanosheet, composition and structure of alloy, and metal-niobate interfacial features will be studied. The effects of surface defect and PdCu alloy on the separation and migration dynamics of photogenerated charges will be studied. To illuminate the reaction mechanism, the effects of surface defect and PdCu alloy on the reactant adsorption and activation behavior in the photocatalytic CO2 process will be explored with the assistance of in situ spectral characterization and theoretical calculation. Through revealing the mechanism underling the synergetic effect on the enhancement of the photocatalytic CO2 activity and selectivity by the surface defect and alloy, the key points on the design of dual active sites system and the highly efficient photocatalytic conversion of CO2 will be obtained. The results of this project will be of great importance for the active site design and performance enhancement of the photocatalytic CO2 reduction systems as well as for the development of solar fuel production technology.

光催化还原CO2制备碳氢燃料是CO2转化与资源化利用的理想途径。课题针对铌酸盐（SnNb2O6、KCa2Nb3O10）超薄纳米片材料转化效率低的问题，提出将表面缺陷改性与PdCu合金修饰同时作用到铌酸盐超薄片，构建新型双活性位点铌酸盐超薄片基光催化体系并应用于还原CO2制备碳氢化合物反应。研究超薄片缺陷浓度、合金组成结构以及金属-铌酸盐界面特性的调控策略及规律。考察表面缺陷与PdCu合金修饰对光生电荷分离及迁移动力学性能的影响。借助原位谱学表征以及理论计算等手段，探究表面缺陷与PdCu合金对CO2还原过程中反应物分子吸附与活化行为的影响，阐明反应机理，进而揭示双位点协同增强CO2还原活性与选择性的作用机制，获得双位点体系设计构建的关键因素，实现CO2高效光催化转化。课题研究结果对光催化还原CO2体系的位点设计与功能强化以及太阳燃料制备技术的发展具有重要的科学价值。

光催化还原 CO2 利用丰富的太阳能资源与半导体材料在常温常压下将 CO2 和 H2O 转化为高附加值的碳氢化合物燃料，被认为是最具前景的 CO2 转化与利用途径之一。 然而，目前通常使用的光催化体系CO2转化效率还不高， 极大地制约了光催化转化 CO2的实际应用。设计与构筑能够有效吸附与活化CO2分子的光催化体系是实现高效CO2转化的关键。本项目以纳米结构半导体与助催化剂等材料的制备和组成结构调控为基础，制备了Pd/HNb3O8-Vo、PtAg/HNb3O8、BiOBr-Vo/HNb3O8、ZnIn2S4/KCa2Nb3O10、MoS2/SnNb2O6、Pd/Cu2O/TiO2、AuCu-TiO2-x、MgAl LDO/VN-CN、Ti3C2Tx/VC-CN、Fe2P/NVsCN等多重活性位点复合光催化体系，总结了体系中表面缺陷浓度、助催化剂组成结构以及助催化剂-半导体界面特性的调控规律。通过紫外-可见吸收光谱、瞬态荧光光谱、原位红外光谱以及理论计算等手段，研究了催化剂组成结构、界面结构等体系单元参数对体系太阳光利用、光生载流子的激发、分离与迁移性质的影响规律，弄清了体系的组成结构与界面电荷分离与迁移动力学性能之间的内在联系，分析了CO2还原反应中反应物与中间体物种的吸附行为，进而揭示了多重活性位点协同增强体系还原CO2活性与选择性的作用机制。该项目研究结果为高效光催化还原CO2体系的位点设计奠定理论基础。