CAS-Climate: RUI: Systematic trends of structure-property relations of metal-organic frameworks built from mixed transition metal ions

第一部分： 随着地球上化石储量的减少，对替代能源的需求对于不断增长的全球人口变得至关重要。此外，由化石燃料污染物引起的严重环境问题也是寻求可再生绿色能源的迫切驱动力。众所周知，在阳光下减少二氧化碳和合适的光催化剂是解决问题的巨大潜力的技术。在材料研究部固态和材料化学项目的支持下，西肯塔基州大学的Bangbo Yan和Pauline Norris开发了新的金属有机框架（MOF）材料，其中包含新的金属络合物，两种不同类型的过渡金属离子通过有机配体连接。这些材料具有基本的功能：它们可以通过一种类型的金属中心吸收可见光，并通过电子转移，例如，利用这种光能通过另一种类型的金属中心催化二氧化碳还原反应。主要研究人员和他们的学生研究过渡金属离子和配体的特性如何影响新MOFs的光催化性能。从这项研究中获得的这些新的MOFs和基础材料化学见解可以帮助控制气候变化和碳足迹，如果它们被集成到未来用于收集太阳能和催化二氧化碳减少的设备中。除了这些科学和潜在的技术影响，这个项目还提供了宝贵的研究机会，在干本科生在西肯塔基大学和当地高中生，包括那些来自代表性不足的群体。 对于这个项目，这是由材料研究部的固态和材料化学计划的支持，主要研究人员合成和研究由金属络合物敏化剂和反应中心组成的新型MOFs。他们假设，有可能设计出通过一种类型的金属中心吸收可见光并通过电子转移的MOF，例如，通过另一种类型的金属中心利用这种光能催化二氧化碳还原反应。为此，他们追求三个不同的目标，旨在研究基础材料化学水平上的合成和结构-性能相关性：第一个目标是设计和研究3d过渡金属离子在异质金属MOFs中的身份的作用和影响;第二个目标是确定改变金属离子的特性的影响（3d、4d或5d）作为异质金属M0 F中的敏化剂;以及第三是鉴定异质金属M0 F的配体效应作为二氧化碳的光催化还原。这些发现有望为设计和构建具有光催化剂等潜在应用的新型MOFs提供重要理论。这种用于太阳能收集和减少二氧化碳的新材料可能有助于控制气候变化和控制碳足迹。此外，研究生（包括本科生和高中生）通过本研究项目接受化学培训和教育。通过他们的科学研究经验，科学写作，并在区域/国家会议上的演讲，学生获得批判性思维，科学方法，写作技巧和沟通技巧的宝贵培训。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

PART 1: NON-TECHNICAL SUMMARY The need for alternative energy sources becomes essential for the growing global population with the dwindling fossil deposits on earth. Moreover, severe environmental problems caused by pollutants from fossil fuels are also imperative driving forces for seeking renewable green energy sources. It is well known that carbon dioxide reductions under sunlight and appropriate photocatalysts are a tremendous potential technology for solving the problem. With the support from the Solid State and Materials Chemistry program in the Division of Materials Research, Bangbo Yan and Pauline Norris of Western Kentucky University, a predominantly undergraduate institution, develop new metal-organic framework (MOF) materials, which contain new metal complexes with two different types of transition metal ions that are connected by an organic ligand. These materials possess an essential feature: they can absorb visible light through one type of metal center and by electron transfer, for example, catalyze carbon dioxide reduction reactions through the other type of metal center using this light energy. The principal investigators and their students study how the identity of the transition metal ions and ligands could affect the photocatalytic properties of the new MOFs. These new MOFs and fundamental materials chemistry insights gained from this study can help control climate change and carbon footprint if they are integrated into devices for harvesting solar energy and catalyzing carbon dioxide reduction in the future. Beyond these scientific and potentially technological impacts, this project also provides valuable research opportunities in STEM to undergraduates at WKU and to local high school students, including those from underrepresented groups.PART 2: TECHNICAL SUMMARY For this project, which is supported by the Solid State and Materials Chemistry program in the Division of Materials Research, the principal investigators synthesize and study novel MOFs consisting of metal-complex sensitizers and reactive centers. They hypothesize that it is possible to design MOFs that absorb visible light through one type of metal center and by electron transfer, for example, catalyze carbon dioxide reduction reactions through another type of metal center with an open metal site using this light energy. To this end they pursue three distinct objectives aimed at studying the synthesis and structure-property correlations at the fundamental materials chemistry level: The first objective is to design and study the role and effect of the identity of 3d transition metal ions in hetero-metal MOFs; the second objective is to determine the effect of changing the identity of metal ions (3d, 4d, or 5d) as a sensitizer in hetero-metal MOFs; and the third is to identify the ligand effects for hetero-metal MOFs as photocatalytic reduction of carbon dioxide. The discoveries are expected to provide an essential theory for the design and construction of new MOFs with potential applications as photocatalysts and beyond. Such new materials for solar energy harvesting and carbon dioxide reduction can potentially help control climate change and control the carbon footprint. In addition, research students (including undergraduate and high school students) receive training and education in chemistry through this research project. Through their scientific research experience, scientific writing, and presentation at regional/national conferences, students gain valuable training in critical thinking, scientific methods, writing skills, and communication skills.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.