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

在这项由化学系化学结构、动力学和机制B(CSDM-B)计划支持的项目中，普渡大学物理和天文学系的尤利娅·普什卡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，太阳能通过产生氢气等清洁燃料转化为化学能。水作为燃料形成反应的电子和质子的来源，但它分解成氢和氧需要在高电势下重新排列化学键。含有富含稀土的铁、钴和锰的分子催化剂可以通过降低电势来促进水的分解，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满足现代社会的能源需求，并促进向二氧化碳中性经济的过渡。这项研究处于物理、化学和材料科学的交界处，其成果有望影响多个领域，并为基础科学、教育、环境和国家能源安全做出贡献。有计划的研究和教育活动旨在增加来自经济困难背景的人数不足的学生的参与，改善女学生在STEM(科学、技术、工程和数学)的经历，通过将研究成果纳入课程来加强对学生的培训，并向学校提供教学单元。本项目的研究重点是人工光合作用的复杂多电子化学过程。目标之一是开发已知的铁基分子水氧化催化剂的新的和详细的研究。铁系催化水氧化中间产物的原位光谱表征将为未来设计更具活性和稳定性的催化剂提供依据。基于同步加速器的X射线近边吸收结构(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等先进的光谱技术将被用来揭示这些催化剂中O-O键的形成机理。我们将从实验上揭示分子结构与催化活性之间的关系，并用密度泛函理论(DFT)对其进行进一步的计算分析。实验技术将提供关于中间体的结构及其电子结构的信息，以及在现场催化过程中样品的电子结构和演变。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.