CAREER: Blueprint for Unlocking New Energy Conversion Functionality in Chalcogenide Frameworks through Precisely Designed Composition, Electronic Structure and Surface Coordination

非技术总结：需要一种全新的材料来实现可持续的太瓦规模的能源基础设施。开发具有促进可再生能源转换和存储特性的功能材料代表了一种有前途的方法，可以直接针对这个问题，这是我们这个时代的决定性挑战之一。该项目由材料研究部固态和材料化学项目以及化学、生物工程、环境和运输系统部门的催化项目共同支持，对国家和全球的可持续性产生了深远的影响，加速了经济上可行的能源转换材料的发现。在这项工作中，正在探索的材料类别具有诸如导电性，太阳能吸收效率和对二氧化碳还原的电化学反应性等特性，这些特性可作为其结构和元素组成的函数进行编程。委拉斯开兹的研究是由实验研究和计算模型的反复结合组成的。该项目的重点是将最先进的材料合成与定制固体材料的电子和结构特性的实验评估相结合，以便将与能量转换相关的特性准确地映射到它们的组成和结构上。这项工作通过预测计算建模方法得到了加强，该方法预测了全新元素组成的有利材料特性，从而以闭环的方式产生新的候选材料。与实验工作并行，本科生和研究生被训练解决固态材料化学和化学工程之间的界面问题；该培训项目特别支持未被充分代表的少数族裔和第一代学生。该教育计划的一个主要推力是通过远程整合现代固态化学和工程研究到高中来补充课程，从而为有抱负的科学家提供成功从事STEM研究所需的工具。技术总结：本研究系统地阐明了对多用途的多维金属硫属化合物的基本理解，通过对原子和电子结构的非原位、原位和操作测量揭示了材料性质描述，以便为电化学和光电化学反应性的预测模型提供信息。PI假设，对局部金属-硫配位、插层电荷密度和二元/三元化学计量的精细控制产生了支持能量转换和存储功能的理想材料特性，包括结合位点亲碳性/亲氧性、框架离子性/共价性和带隙/位置。为了评估这一假设，我们系统地修改了固态硫族化物框架中小分子吸附位点的组成和局部几何形状，以便通过实验和计算阐明与化学和物理性质相关的功能趋势。这些修改的实验结果为预测机器学习密度泛函理论模型提供了信息，这些模型反过来生成候选框架组合，从而产生最佳属性。这种方法有效地关闭了实验和理论之间的反馈回路；因此,本研究的预期产品新金属硫族化物材料和异质结构的1 d M2Mo6X6 (M = K, Rb, Cs; X =年代,Te), 2 d ((M =钛、钼、W; X =年代,Te),和0 d / 3 d MyMo6X8 (M =碱、碱性过渡,和/或后过渡金属;y = 0 - 4; X = O,年代,Te)构成空间,可以预见产生含氧燃料,调解散装和界面电荷传输,使可调光子吸收。更重要的是，这项研究有望产生一种材料设计工具集，说明在产生理想的固态性能时，理论、合成、结构解析和电子结构研究之间成功迭代相互作用的重要性。这项工作的智力价值源于其对材料设计的综合方法，其中对成分和结构对紧急物理性质，化学反应性和能量转换相关功能的影响的基本理解被解开。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。

Non-Technical Summary: An entirely new palette of materials is required to enable a sustainable terawatt-scale energy infrastructure. The development of functional materials with properties that facilitate renewable energy conversion and storage represents a promising approach that takes direct aim at this problem, one of the defining challenges of our time. This project, which is supported jointly by the Solid State and Materials Chemistry program in the Division of Materials Research and the Catalysis program in the Division of Chemical, Bioengineering, Environmental and Transport Systems, has far-reaching impact on both national and global sustainability, the accelerated discovery of economically viable energy conversion materials. The classes of materials being explored in this effort have properties such as electrical conductance, efficacy of solar-energy absorption, and electrochemical reactivity towards carbon dioxide reduction that are programmable as a function of their structure and elemental make-up. PI Velazquez’s study is comprised of an iterative combination of experimental research and computational modeling. The focus of this project is to combine state-of-the-art materials synthesis with experimental evaluation of electronic and structural properties in tailor-made solid-sate materials such that their properties of relevance to energy conversion can be accurately mapped to their composition and structure. This effort is augmented by a predictive computational modeling approach where favorable material properties are predicted for entirely new elemental compositions, thereby yielding new candidate materials in a closed-loop manner. In parallel with the experimental effort, undergraduate and graduate students are trained to solve problems at the interface between solid-state materials chemistry and chemical engineering; the training program specifically supports underrepresented minority and first-generation students. A major thrust of the educational plan involves curriculum supplementation through remote integration of modern solid-state chemistry and engineering research into high schools, thereby providing aspiring scientists with the tools required to successfully engage in STEM research. Technical Summary: This research systematically elucidates fundamental understanding of versatile classes of multi-dimensional metal chalcogenides, revealing material property descriptors through ex situ, in-situ, and operando measurements of atomistic and electronic structure in order to inform predictive models for electrochemical and photoelectrochemical reactivity. The PI hypothesizes that fine control over local metal-chalcogen coordination, intercalant charge density, and binary/ternary stoichiometry engenders desirable material properties that underpin energy conversion and storage functionality, including binding-site carbophilicity/oxophilicity, framework ionicity/covalency, and band gap/positions. To evaluate this hypothesis, the composition and local geometry of small-molecule adsorption sites in solid-state chalcogenide frameworks are systematically modified across the span of a substantial design space in order to experimentally and computationally elucidate trends in functionality that correlate with chemical and physical properties. Experimental results borne out of these modifications inform predictive machine learning-density functional theory models, which in turn generate candidate framework compositions that will engender optimal properties. This approach effectively closes a feedback loop between experiment and theory; as such, the anticipated products of this study are new metal chalcogenide materials and heterostructures from the 1D M2Mo6X6 (M = K, Rb, Cs; X = S, Se, Te), 2D MX2 (M = Ti, Mo, W; X = S, Se, Te), and 0D/3D MyMo6X8 (M = alkali, alkaline, transition, and/or post transition metal; y = 0–4; X = O, S, Se, Te) composition spaces that predictably yield oxygenated fuels, mediate bulk and interfacial charge-transport, and enable tunable photon absorption. More importantly, this research is expected to yield a materials design toolset that illustrates the importance of successfully iterative interplay between theory, synthesis, structure elucidation, and electronic structure studies when it comes to generating desirable solid-state properties. The intellectual merit of this work stems from its integrative approach to material design, where a foundational understanding regarding the effects of composition and structure on emergent physical properties, chemical reactivity, and energy conversion-related functionality is unraveled.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.