Photochemical Water Splitting at Soft Interfaces

尽管过去几年可见光催化剂在直接水分解方面取得了重大进展，但为了达到应用，耐久性和周转率必须得到提高，并且二氧和二氢生成步骤的结合仍然是一个挑战。用于水分解的分子光催化剂通常由几种组分组成。我们提出将光活性两亲性组分共嵌入到水-脂界面的膜结构中，使多组分催化剂体系的二维阵列易于组装。催化剂亚基在界面处的接近性和较高的局部浓度提高了光催化性能。嵌入染料、催化剂和膜两亲体组成的简单变化允许快速优化多组分催化剂。根据所应用的两亲化合物的性质，可以影响化合物在界面上的空间分布，从而导致高活性的催化剂斑块。由于聚合体的动态特性，聚合体的自我修复可以延长光催化剂的稳定性。中国申请者开发了基于金属配合物的多组分催化剂，用于可见光驱动水氧化和制氢。这些催化剂属于目前已知的性能最好的体系。这家德国集团在金属配合物的膜嵌入和有机染料作为光敏剂的使用方面拥有丰富的经验。理想的互补专业知识将结合起来，开发具有嵌入式多组分光催化剂的功能化囊泡和膜，并优化其性能。一项已经完成的联合初步研究表明，这种功能化囊泡在蓝光下表现出光催化水氧化的性能，并且超过了均相溶液中的组分。部分金属络合光催化剂将被氧化还原活性有机染料取代，以降低体系的整体金属含量。产氢催化剂将被共嵌入以获得同时产氧和产氢的膜。功能化囊泡将在均相溶液中进行研究和优化，然后转移到表面或使用打印技术进行处理。这将使具有分层结构的复杂多组分光活性器件的制备变得容易。通过参与小组之间的博士生和博士后交流以及小组之间的年度联合研讨会，确保了项目内的知识转移和密切合作。

Although significant progress was made over the last years in the performance of visible light photocatalysts for direct water splitting, durability and turn over numbers must be improved to reach applications and the combination of the dioxygen and the dihydrogen generating steps remains a challenge. Molecular photocatalysts for water splitting typically consist of several components. We proposed the co-embedding of photoactive amphiphilic components into membrane structures at the water-lipid interface allowing facile assembly of two dimensional arrays of multi-component catalyst systems. The close proximity and the high local concentration of the catalyst subunits at the interface increase the photocatalytic performance. Simple variation of the composition of the embed¬ded dyes, catalysts and membrane amphiphiles allows the rapid optimization of the multi component catalysts. Depending on the nature of the applied amphiphiles the spatial distribution of compounds at the interface can be influenced leading to catalyst patches of high activity. Due to the dynamic nature of the assemblies self-repair of the aggregates should lead to a prolonged stability of the photocatalysts.The Chinese applicants have developed metal complex based multi-component catalysts for visible light driven water oxidation and hydrogen generation. The catalysts belong to the best performing systems currently known. The German group has experience in membrane embedding of metal complexes and the use of organic dyes as photosensitizers. The ideally complementary expertise will be combined to develop functionalized vesicles and membranes with embedded multi-component photocatalysts and the optimization of their performance. An already completed joint initial study revealed that such functionalized vesicles show photocatalytic water oxidation using blue light and exceed the performance of the components in homogeneous solution. Part of the metal complex photocatalysts will be replaced by redox active organic dyes to reduce the overall metal content of the system. Hydrogen generating catalysts will be co-embedded to obtain membranes performing simultaneous oxygen and hydrogen generation. Functionalized vesicles will be investigated and optimized in homogeneous solution, and then transferred onto surfaces or processed using printing technology. This will allow the facile preparation of complex multi-component photoactive devices with hierarchical architecture. Knowledge transfer and intensive collaboration within the project is ensured by exchange of PhD students and postdocs between the participating groups and an annual joint workshop of the groups.