CAS: Reaction Mechanisms in 3d Transition Metal Complexes for Artificial Photosynthesis

在这个由化学学部化学结构、动力学与机制B （CSDM-B）项目支持的项目中，普渡大学物理与天文学系的Yulia Pushkar教授将为人工光合作用开发新的分子解决方案。在人工光合作用中，太阳能通过产生氢等清洁燃料转化为化学能。水是燃料形成反应的电子和质子的来源，但要想分裂成氢和氧，需要在高电位下重新排列化学键。含有地球上丰富的铁、钴和锰的分子催化剂可以通过降低电位来促进水的分解，从而提高能量转换效率。人工光合作用的发展及其大规模实施有望解决现代社会的能源需求，并促进向二氧化碳中性经济的过渡。该研究处于物理、化学和材料科学的交叉点，其成果有望影响多个领域，为基础科学、教育、环境和国家能源安全做出贡献。计划中的研究和教育活动旨在增加来自经济弱势背景的代表性不足的学生的参与，改善女学生在STEM（科学、技术、工程和数学）方面的经验，通过将研究成果纳入课程来加强对学生的培训，并向学校提供教学模块。本项目主要研究人工光合作用复杂的多电子化学过程。目标之一是开发新的和详细的研究已知的铁基分子水氧化催化剂。使用铁系统催化水氧化中间体的原位光谱表征将为未来设计更活跃和稳定的催化剂提供信息。先进的光谱技术，如基于同步加速器的x射线吸收近边结构（XANES）、扩展x射线吸收精细结构（EXAFS）、x射线发射、电子顺磁共振（EPR）和多波长动力学共振拉曼，将用于揭示这些催化剂中O-O键形成的机制。分子结构与催化活性之间的关系将通过实验揭示，并进一步利用密度泛函理论（DFT）进行计算分析。实验技术将提供有关中间体结构及其电子构型和样品在原位催化过程中的演变的信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project supported by the Chemical Structure, Dynamics & Mechanisms B (CSDM-B) Program of the Chemistry Division, Professor Yulia Pushkar of the Department of Physics and Astronomy at Purdue University will develop new molecular solutions for artificial photosynthesis. In artificial photosynthesis, solar energy is converted into chemical energy through generation of clean fuels such as hydrogen. Water serves as a source of electrons and protons for fuel forming reaction but its splitting into hydrogen and oxygen requires rearrangement of chemical bonds at high potential. Molecular catalysts which contain earth-abundant iron, cobalt and manganese can facilitate water splitting by lowering the potential and, thus, boosting energy conversion efficiencies. The development of artificial photosynthesis and its large-scale implementation is expected to address the energy needs of modern society and facilitate transition to a CO2 neutral economy. This research lies at the interface of physics, chemistry and materials science, with results expected to impact diverse fields and contribute to fundamental science, education, environment and national energy security. Planned research and educational activities are designed to increase participation of under-represented students from economically disadvantaged backgrounds, improve experiences of female students in STEM (Science, Technology, Engineering and Mathematics), enhance training of students via integration of research results into curriculum and to deliver teaching modules to schools. Research in this project focuses on the complex multielectron chemical process of artificial photosynthesis. Among the goals is the development of new and detailed studies of known Fe-based molecular water oxidation catalysts. In situ spectroscopic characterization of intermediates in catalytic water oxidation using Fe systems will inform future design of more active and stable catalysts. Advanced spectroscopic techniques such as synchrotron-based X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), X-ray emission, electron paramagnetic resonance (EPR), and multi-wavelength kinetic resonance Raman will be used to uncover mechanism of O-O bond formation in these catalysts. The relationship between molecular structure and catalytic activity will be uncovered experimentally and further analyzed computationally using density functional theory (DFT). Experimental techniques will deliver information on the structure of the intermediates and their electronic configuration and evolution of samples during the catalytic processes in situ.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.