CAS: Designing Efficient Electrocatalysts for Selective Reduction of CO2 to Carbon-Rich Products

在化学系化学催化项目的支持下，来自密苏里州科技大学的Manashi Nath博士（PI）和Julia Medvedeva博士（共同PI）正在设计新的催化剂，用于将二氧化碳电化学还原为增值化学品和燃料。该项目旨在通过结合基于实验和计算的方法来设计高效的电催化剂组合物，以增强催化剂表面的CO2还原。该项目正在进一步制定从容易获得和丰富的金属中提取的这种催化剂的设计原则。这个多学科项目涉及本科生，研究生和博士后研究人员合作的方法，涉及化学，电化学，物理学和表面科学的新催化剂组合物的发现。该项目产生的知识属于清洁能源的更广泛范围，将通过各种机制，包括会议介绍、公开研讨会、同行评审出版物和外联活动，向各级科学界传播。具体而言，将与当地STEM俱乐部Kaleidoscope合作，为当地高中和初中学生设计示范实验和研讨会，该俱乐部组织课后STEM活动。公众对二氧化碳捕获和转化的认识将通过圣路易斯科学中心的外联活动、密苏里州ST开办的少数族裔工程学入门（MITE）营地以及夏季为当地高中教师组织的讲习班来实现。这些活动将包括使用本研究项目开发的催化剂制成的活性CO2电还原电池的现场演示。在化学部化学催化计划的支持下，来自密苏里州科技大学的Manashi Nath博士（PI）和Julia Medvedeva博士（联合PI）&正在研究设计用于将二氧化碳电还原为碳的有效催化剂组合物。丰富的还原产物，包括燃料和其他增值化学品。PI提出，CO2还原为较长碳链产物是催化活性过渡金属位点处的化学势与催化剂表面上的中间CO（一氧化碳）吸附能之间的微妙相互作用。该提议的中心假设是，高d-电子占据率与过渡金属中心的小于完全填充的构型一起沿着与金属配体键的更大的共价性将导致在较低的施加电势下对C2还原产物的更高的选择性。具体而言，有人提出，增加停留时间的中间CO吸附在催化剂表面上将导致进一步的后续还原CO富碳产品。PI旨在通过控制过渡金属位点上的d-电子密度来增加CO中间体在催化剂表面上的停留时间，所述d-电子密度对金属-配体背键有直接影响，所述背键可以将CO吸附能调节到特定范围内（弱吸附状态和强吸附状态之间）。该假设将通过在系统组合电沉积之后合成包含Cu、Ni、Fe、Mn和V的二元、三元和四元过渡金属硫族化物（硒化物和碲化物）来测试。实验研究将与DFT（密度泛函理论）计算补充，其中CO和CO2吸附动力学将在不同的催化表面上进行估计，并与它们的性能相关。该项目的具体任务包括：（一）改变硫族化物系列中的阴离子，并研究作为电负性函数的催化活性;（二）在过渡金属位点进行异价取代，这将导致d-电子云的重新分布，增加过渡金属中心的氧化还原可调性，并促进多电子转移;（iii）纳米结构化功能催化剂以增加活性表面积。该项目的主要交付成果将是非贵金属基二氧化碳电还原催化剂，它可以以更少的电能消耗生产更高的碳氢化合物基燃料。从这项全面的研究中获得的基本见解有可能阐明用于设计更有效的碳捕获催化剂的设计原则。该奖项反映了NSF的法定使命，并被认为值得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来支持。

With the support of Chemical Catalysis program in the Division of Chemistry, Drs. Manashi Nath (PI) and Julia Medvedeva (co-PI) from Missouri University of Science & Technology are designing new catalysts for the electrochemical reduction of carbon dioxide to value-added chemicals and fuels. The project aims to design efficient electrocatalyst compositions by combining an experimental- and computational-based approach that enhance CO2 reduction on the catalyst surface. The project is further developing design principles for such catalysts derived from readily available and abundant metals. This multidisciplinary project involves undergraduate, graduate, and postdoctoral researchers collaborating on approaches involving chemistry, electrochemistry, physics, and surface science for the discovery of new catalyst compositions. Knowledge generated from this project, falling under the broader scope of clean energy, will be disseminated to the scientific community at all levels employing various mechanisms including conference presentations, public seminars, peer-reviewed publications, and outreach activities. Specifically, demonstration experiments and workshops will be designed for local high school and middle school students by collaborating with a local STEM club, Kaleidoscope, which organizes after-school STEM activities. Public awareness of carbon dioxide capture and conversion will be accomplished through outreach activities at the St. Louis Science Center, through Minority Introduction to Engineering (MITE) camps run by Missouri S&T, and through workshops organized during the summer for local high school teachers. These activities will include live demonstrations of an active CO2 electroreduction cell made by employing catalysts developed in this research project.With the support of Chemical Catalysis program in the Division of Chemistry, Dr. Manashi Nath (PI) and Dr. Julia Medvedeva (co-PI) from Missouri University of Science & Technology are studying designing efficient catalyst composition for electroreduction of carbon dioxide to carbon-rich reduction products comprising fuels and other value-added chemicals. The PIs propose that CO2 reduction to longer carbon chain products is a delicate interplay between chemical potential at the catalytically active transition metal site and intermediate CO (carbon monoxide) adsorption energetics on the catalyst surface. The central hypothesis of this proposal is that high d-electron occupancy with less than a fully filled configuration of the transition metal center along with greater covalency of the metal ligand bond will lead to more selectivity for C2 reduction products at lower applied potential. Specifically, it is proposed that increasing dwell time of the intermediate CO adsorbed on the catalyst surface will lead to further subsequent reduction of CO to carbon-rich products. The PIs aim to increase dwell time of the CO intermediate on catalyst surface by controlling the d-electron density on the transition metal site that has a direct effect on the metal-to-ligand back bonding which can tune the CO adsorption energy to be within a specific range (between weak and strong adsorption regimes). This hypothesis will be tested by synthesizing binary, ternary, and quaternary transition metal chalcogenides (selenides and tellurides) comprising Cu, Ni, Fe, Mn, and V, following systematic combinatorial electrodeposition. Experimental studies will be complemented with DFT (Density Functional Theory) calculations where CO and CO2 adsorption kinetics will be estimated on different catalytic surfaces and correlated with their performance. Specific tasks of this project include: (i) changing the anions across the chalcogenide series and investigating catalytic activity as a function of electronegativity; (ii) aliovalent substitution at the transition metal site which will lead to redistribution of the d-electron cloud increasing redox tunability of the transition metal center as well as facilitate multielectron transfer; (iii) nanostructuring the functional catalysts to increase the active surface area. Major deliverable of this project will be non-precious-metal-based CO2 electroreduction catalysts that can produce higher hydrocarbon-based fuels with lesser expense of electrical energy. Fundamental insights gained from this comprehensive study have the potential to illuminate design principles used to design more efficient catalysts for carbon capture.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.