基于三维有序大孔/介孔TiO2基纳米复合物的光热化学分解CO2研究

To dissociate carbon dioxide (CO2) into CO and O2 via the photo-thermochemical cycle(PTC) is one of the most promising methods for solar energy driven CO2 utilization. There are two key limitations for high energy conversion efficiency: low photo-induced VO production efficiency, and slow CO2 splitting rate. The photo-thermochemical CO2 splitting reaction involves several basic process: light absorption, charge separation, the production of VO, adsorption and activation of CO2, surface catalytic reaction, therefore, metal cocatalysts/(TiO2-CeO2) nanocomposites were designed as the new active materials. Three-dimensionally ordered macro/mesoporous titania can produce photo-induced VO in high efficiency, and CeO2 was supported on 3DOMM TiO2 for fast CO2 adsorption and decomposition process. In addition, suitable cocatalysts was introduced to catalyze the surface reactions by lowering the activation energies, and suppress the recombination of photogenerated electrons and holes. The structure-activity relationship of the nanocomposites in PTC revealed by investigating the effects of the composition, microstructure, surface property of the mutil-metal oxides, the basic property and the interface structure. Electron spin resonance(ESR), photoluminescence (PL), in-situ Raman, in-situ FTIR were employed to elucidate mechanisms of the generation of photo-induced oxygen vacancy and the CO2 splitting reaction. The essential factors for energy conversion efficiency would be revealed, and then the new and more effective catalyst systems could be designed from the molecular / atomic level.These studies will not only provide new ideas for CO2 utilization, but also provide some theoretical basis for high efficiency photo-thermal construction.

以太阳能作为能量来源，通过光热化学耦合过程，将CO2转化为化学燃料，对低碳减排以及太阳能利用均具有重要研究意义。针对影响该过程能量转化效率的两个核心问题：光致氧空位产生效率低、CO2与表面氧空位反应速率慢，综合考虑光吸收、电荷分离、氧空位形成、CO2吸附活化以及表面催化等基本过程，本申请提出基于三维有序多级孔道结构构筑金属助催化剂/(TiO2-CeO2)三元纳米复合物。研究复合体系的组成、微观结构、表面酸碱性、各组分之间的界面设计等对CO2转化率和CO2分解速率的影响规律，借助ESR、原位红外、原位Raman等表征手段探索光致氧空位的产生机制，CO2与表面氧空位的作用机理，揭示影响光热化学循环过程能量转化效率的本质因素，为从分子/原子水平设计新型高效活性材料提供实验指导和理论依据。本申请的实施不仅为CO2转化利用提供新的思路，也为高效光热耦合过程的探索提供理论和技术支持。

本项目针对光热化学分解CO2反应中的两个核心问题：氧空位产生效率低、CO2与表面氧空位反应速率慢；筛选合适的金属催化剂(IrO2, Cu, Pd, Au)与三维多级孔道结构的金属氧化物(Ce1-xZrxO2, TiO2, In2O3)组成复合催化剂体系，用于提升CO2分解过程的能量转化效率。研究复合体系的组成、微观结构、各组分之间的界面设计等对氧空位产生效率，CO2转化率和CO2分解速率的影响规律，分析了CO2与表面氧空位反应动力学过程，揭示了影响光热化学分解CO2性能的关键因素。主要研究结果为：(1)研究了IrO2催化剂对于Ce1-xZrxO2固溶体分解CO2性能的影响，H2-TPR，Raman，MIEC揭示了IrO2活化晶格氧机制，动力学分析证明了IrO2可加快CO2分解的表面反应过程。(2)构建了(Cu, Pd, Au)/3DOM TiO2体系用于光热化学分解CO2反应，证实了三维有序孔道结构及金属催化剂均可以提升光热CO2分解反应性能。(3)以MIL-In(68)为模板，构建了(Cu, Ga, Pd)掺杂的In2O3体系用于光热化学分解CO2反应。(4)在此研究的基础上，与课题组其他老师的工作交叉融合，拓展了CO2资源化利用的其他途径，探索了金属-CO2电池相关的研究。在本项目的资助下，目前已发表SCI论文8篇(第一/通讯作者5篇)，培养硕士研究生4名，指导本科毕业设计论文12名。本项目的实施与完成为太阳能光热转化CO2反应提供了一定的实验依据和理论指导，为基于氧空位的光热化学催化体系的筛选提供了实验依据，加深了光热CO2分解反应动力学过程的认识，为CO2资源化利用提供了其他可参考途径。