Integrating polyoxometalate-single atom catalyst based (photo-) electrodes in flow reactors for reductive and oxidative nitrogen activation

在本项目中，我们建议开发能够耦合氮-铵还原反应（NRR）和氮-硝氧化反应（NOR）的光电化学驱动反应器，从而实现从氮、水、阳光和可持续电力中生产硝酸铵的自主流动光反应器。该项目结合了从新型催化剂合成和稳定电极沉积到反应器设计和反应器内材料集成的概念。该项目将金属氧化物催化剂和（光）电极功能化（PI Streb）的专业知识与反应工程、质量传输优化和光反应器设计（PI Ziegenbalg）的专业知识结合起来。在第一个资助期（36个月），该项目将开发无贵金属单原子催化剂（SACs， 1个金属反应中心）和单位点催化剂（ssc， 2个金属反应中心），锚定在分子金属氧化物（多金属氧酸盐，pom）上。SAC/SSC金属位置的变化将允许控制NRR/NOR性能，而pom锚定将提供稳定的、定义良好的全氧协调环境。这些分子前体沉积在高孔隙率（光）电极上，通过湿化学、微波或水热pom转化为固态氧化物来实现，以促进催化剂和电极之间稳定的机械和电气连接。电极集成到3d打印流动光反应器将实现快速原型设计和化学和反应工程要求的快速匹配。这些系统将通过现场/操作（光电）电化学研究和（合作）理论建模进行研究。这将提供从原子到反应器水平对催化性能及其局限性的见解，并使我们能够确定关键的优化参数。第一个资助期的重点是研究半电池装置中的NRR和NOR，用于机械研究和材料设计/优化，而第二个资助期的目标是集成的全电池光反应器。总而言之，该项目将从分子氮开始开发用于分散硝酸铵生产的流动光反应器，并使用现代材料设计，先进的电极制造和反应工程来解决从分子到反应器水平的挑战。

In this project, we propose the development of photo-electrochemically driven reactors capable of coupling the nitrogen-to-ammonium reduction reaction (NRR) and the nitrogen-to nitrate oxidation reaction (NOR), leading to autonomous flow photoreactors for ammonium nitrate production from nitrogen, water, sunlight, and sustainable electricity. The project combines concepts from novel catalyst synthesis and stable electrode deposition to reactor design and materials-in-reactor integration. The project combines expertise in metal oxide catalysts and (photo-)electrode functionalization (PI Streb) with expertise in reaction engineering, mass transport optimization and photoreactor design (PI Ziegenbalg). In the first funding period (36 months), the project will develop noble-metal-free single atom catalysts (SACs, 1 metal reaction center) and single-site catalysts (SSCs 2 metal reaction centers) anchored to molecular metal oxides (polyoxometalates, POMs). Variation of the SAC/SSC metal sites will allow control of NRR/NOR performance, while POM-anchoring will provide a stable, well-defined all-oxo coordination environment. Deposition of these molecular precursors on high-porosity (photo-)electrodes is achieved by wet-chemical, microwave or hydrothermal POM-conversion to solid-state oxides to facilitate stable mechanical and electrical linkage between catalyst and electrode. Electrode integration into 3D-printed flow photoreactors will enable rapid prototyping and fast matching of chemical and reaction-engineering requirements. The systems will be studied by in situ/operando (photo-)electrochemical studies and – in collaboration – by theoretical modelling. This will provide insights from the atomic to the reactor-level on the catalytic performance, its limitations, and enable us to identify key optimization parameters. The first funding period is focused on studying NRR and NOR in half-cell setups for mechanistic investigations and materials design/optimization, while the second funding period will target the integrated full-cell photoreactors. In sum, this project will develop flow photoreactors for decentralized ammonium nitrate production starting from molecular nitrogen, and uses modern materials design, advanced electrode fabrication and reaction engineering to address challenges from the molecular to the reactor level.