双金属共掺杂SrTiO3产氢光催化剂形貌和晶面调控及其晶面间光生电荷分离研究

One of the key scientific issues in photocatalytic hydrogen production is efficient separation and transfer of photogenerated charges. It has been reported that the separation efficiency of charge carriers can be greatly improved by the synergistic effect between different facets of photocatalyst. Despite its importance, only a few reports have been focused on investigation of the synergistic mechanism of charge separation and transfer between different facets. Based on previous research and preliminary exploration, we propose the study of morphology and crystal facet tailoring and photogenerated charge separation on different facets of bimetal codoped SrTiO3 photocatalyst for hydrogen evolution. The strategy combining sol-gel hydrothermal method with molten salt method is applied to controllable fabrication of photocatalyst with specific morphologies and crystal facets, and the correlations among morphology, crystal facet and photocatalytic hydrogen production are investigated. Combined with quantum chemical calculation, the reaction activity of reduction and oxidation on different crystal facets will be studied by selective deposition of noble metal and metal oxide on the surface of photocatalyst by photo-reduction and photo-oxidation methods, respectively. Moreover, spatially resolved surface photovoltage spectroscopy, time-resolved photoluminescence spectroscopy and transient absorption spectroscopy will be employed to clarify the essential difference in reduction and oxidation ability on different crystal facets and the mechanism of photogenerated charge separation and transfer between different facets. This project would provide theoretical and practical basis for design and synthesis of high-efficiency photcatalyst for hydrogen evolution.

光生电荷的有效分离和传输是光催化产氢领域的关键科学问题之一。研究显示，光催化剂不同晶面间的协同效应可以促进光生电荷的有效分离。然而目前对于晶面协同效应的本质以及光生电荷在不同晶面间的分离和迁移机制的研究较少。基于以往研究积累和前期探索，本项目提出双金属共掺杂SrTiO3产氢光催化剂形貌和晶面调控及其晶面间光生电荷分离研究。采用溶胶凝胶水热法和熔盐法两步相结合的策略合成具有不同形貌和暴露晶面的光催化剂，并探究形貌、晶面以及光催化产氢性能之间的构效关系。通过选择性的在光催化剂表面光还原沉积金属或光氧化沉积金属氧化物的方法并结合量化计算研究不同暴露晶面的还原和氧化反应性能。采用空间分辨表面光电压谱、时间分辨荧光光谱以及瞬态吸收光谱等表征技术，揭示不同晶面氧化和还原性能存在差异的本质，阐明晶面间协同效应促进光生电荷分离和传输的机制。本项目的开展将为高效产氢光催化剂的设计合成提供理论和实践基础。

光生电荷的有效分离和传输是光催化产氢领域的关键科学问题之一。研究显示，光催化剂不同晶面间的协同效应可以促进光生电荷的有效分离。然而目前对于晶面协同效应的本质以及光生电荷在不同晶面间的分离和迁移机制的研究较少。本项目围绕La和Cr共掺杂钛酸锶（缩写为SrTiO3(La,Cr)）光催化剂不同晶面光生载流子迁移特性及其产氢性能进行研究。采用溶胶凝胶水热法和熔盐法两步相结合的策略合成具有不同形貌和暴露晶面的光催化剂，并探究形貌、晶面以及光催化产氢性能之间的构效关系。通过溶胶凝胶水热法和聚合络合法分别合成SrTiO3(La,Cr)。利用光合作用中Z机制的概念将两种方法合成的产氢光催化剂Pt/SrTiO3(La,Cr)和产氧光催化剂PtOx/WO3耦合，并在I-/IO3-氧化还原电对存在下考察可见光分解水同时产氢和产氧活性。此外，研究了掺杂量对SrTiO3的形貌、带隙以及光催化活性的影响。还详细研究了制备过程中使用的溶剂对光催化性能的影响。最后，以乙醇为溶剂，采用溶胶-凝胶溶剂热法制备了一系列Ti3+自掺杂的SrTiO3光催化剂。制备的SrTiO3样品具有明显的可见光响应，在可见光照射下表现出较高的光催化产氢活性。