Collaborative Research: SUSCHEM: Engineering Polymer-Nanocatalyst Membranes for Direct Capture of CO2 and Electrochemical Conversion to C2+ Liquid Fuel

由于温室气体如CO2的排放增加，环境问题日益严重。管理CO2水平的一种有效方法是直接捕获并将CO2从空气中转化为其他碳形式。使用空气作为原料将CO2直接转化为可重复使用的碳产品是极其困难的，目前的方法通常涉及额外的能源密集型步骤来生产纯CO2作为后续催化转化的原料。该提案将解决目前尚未解决的挑战，以允许直接空气捕获，捕获/释放时的能量输入最小，并将CO2连续电还原为增值液体燃料。该概念基于新型生物启发工艺的设计。核心组件是一种纤维素膜，直接用于从空气中捕获和分离CO2。这种新的捕获反应，以前还没有研究过，将提供一个非常强大的处理工具，直接空气捕获二氧化碳。为了将二氧化碳转化为可重复使用的碳，将研究一类新的地球丰富的钴催化剂（六方密堆积的钴纳米片）。通过纤维素-石墨烯-钴体系可以方便地实现CO2的捕获和转化，该体系可以合理地控制催化剂的局部碱度和CO2的接近度，以促进CO2的高效电还原。通过布朗大学和康涅狄格大学的合作，该研究将产生一个创新的一体化集成系统的设计，以实现可持续的CO2捕获和利用。该提案旨在开发一种新型的电化学系统，用于在环境条件下直接捕获空气并将CO2转化为乙醛和/或乙醇。该系统由天然纤维素和沉积在石墨烯上的新型六方钴纳米片催化剂组成，提供了一种高导电性和多孔性的聚合物网络，其中两种组分在直接空气捕获和CO2电还原中协同工作。富含羟基的无定形纤维素可以在碱催化下以亚稳半碳酸盐的形式捕集CO2。这些亚稳态半碳酸盐可以在pH变化或温和加热时可逆地释放CO2，提供了一种高效节能的CO2捕获和释放方法，这是受到光合作用中天然CO2浓度机制的启发。释放的CO2接近组装在石墨烯上并整合到纤维素膜中的坚固的钴纳米片催化剂，其用作工作电极以进行CO2到C2产物的选择性电还原。一个工作的流通池系统将被证明是一种工程方法，直接捕获和转化二氧化碳与空气作为原料。该研究不仅为纤维素加工方法的设计提供了新的思路，为钴纳米片促进CO2还原反应中的C-C偶联提供了新的基础知识，也是一种能量该项目的一部分将在布朗大学完成，由电化学系统计划和刺激竞争的既定计划共同资助。研究（EPSCoR）。该奖项反映了NSF的法定使命，并被认为是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的支持。

There have been rising environmental concerns resulting from the increasing emission of greenhouse gasses like CO2. One effective way to manage CO2 level is to directly capture and convert CO2 from air to other carbon forms. The direct conversion of CO2 using air as feedstock to a reusable carbon product has been extremely difficult and current approaches often involve an additional energy-intensive step to produce pure CO2 as feedstock for subsequent catalytic conversion. This proposal will address the current unmet challenges to allow direct air capture with a minimum energy input on capture/release and sequential electroreduction of CO2 to value-added liquid fuels. The concept is based on the design of a novel bioinspired process. The central component is a cellulose-based membrane that is used directly for capture and separation of CO2 from air. This new capture reaction, not yet been studied previously, will provide a very powerful processing tool for direct air capture of CO2. To convert CO2 to a reusable form of carbon, a new class of earth-abundant cobalt catalyst (hexagonal close packed cobalt nanosheets) will be studied. The capture and conversion will be realized conveniently via the cellulose-graphene-cobalt system in which local basicity and CO2 proximity to the catalyst are rationally controlled to facilitate efficient electroreduction of CO2. Through collaborative efforts between Brown and UConn, the proposed studies will generate an innovative design of an all-in-one integrated system to realize sustainable CO2 capture and utilization.This proposal aims to develop a novel electrochemical system for direct air capture and conversion of CO2 to ethanal and/or ethanol under ambient conditions. The system consists of natural cellulose and a new hexagonal cobalt nanosheet catalyst deposited on graphene, providing a highly conductive and porous polymer network where the two components work cooperatively in direct air capture and electroreduction of CO2. Hydroxyl-rich amorphous cellulose can capture CO2 in the form of metastable hemi-carbonates catalyzed by a base. These metastable hemi-carbonates can reversibly release CO2 upon pH change or gentle heating, providing an energy-efficient approach to CO2 capture and release, which is inspired by natural CO2 concentration mechanisms in photosynthesis. The released CO2 is in proximity of the robust cobalt nanosheet catalyst assembled on graphene and integrated into the cellulose membrane, which functions as a working electrode to carry out the selective electroreduction of CO2 to C2 products. A working flow-cell system will be demonstrated as an engineering approach to direct capture and conversion of CO2 with air as feedstock. The study will offer not only a new design concept on cellulose processing method and new fundamental knowledge on the cobalt nanosheet-promoted C-C coupling in the CO2 reduction reaction, but also an energy-efficient engineering solution to direct CO2 capture and conversion.The portion of this project that will be completed at Brown University is jointly funded by the Electrochemical Systems Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.