CAREER: Electrochemically Mediated Carbon Dioxide Separation via Non-Aqueous Proton-Coupled Electron Transfer

从固定排放器和环境空气中有效捕获二氧化碳（CO2）对于实现气候目标至关重要。然而，用于CO2捕获的常规热化学方法是能量密集型的、成本高昂的并且依赖于化石燃料。另一方面，由电化学反应驱动的新兴碳捕获方法承诺温和的操作条件，耦合到间歇性可再生能源的灵活性，并且由于其模块化可以适应碳捕获需求的多尺度性质。然而，现有电化学碳捕获过程的实际部署仍然受到诸如氧敏感性和蒸发损失的问题的阻碍。相应地，该项目探索了通过电化学刺激调节碳捕获的新概念。该概念涉及在电极表面生成低挥发性、空气稳定的CO2吸附剂，然后在吸收器单元中捕获CO2，随后在切换电极极性时释放CO2。我们的目标是了解并最终利用控制热力学，反应动力学和模型电化学系统的传输特性，利用材料合成，表征和电分析的多模式工具包。更广泛的影响涉及从高中到研究生阶段的教育和辅导活动，以培养具有解决人类可持续性挑战所必需的跨学科技能的年轻一代工程师，其中包括开发关于碳捕获的高中实验室模块，并将分离方法和界面科学的进步纳入大学的化学工程课程。该项目旨在研究一种由氧化还原可调的布朗斯特碱部分组成的电化学界面，该界面可以在非水电解质中进行质子耦合电子转移（PCET），用于可逆（再）生成空气稳定的CO2吸附剂。在分子水平上，分子结构，布朗斯台德碱度和PCET能量之间的关系将被描绘，通知碳捕获化学的合理设计。在材料水平上，将合成微孔电极以检查电极微结构与相应的质量和电荷传输行为之间的相互作用。电解质环境对PCET和CO2化学吸附动力学的影响也将通过（电）分析技术进行系统研究。最后，CO2分离概念将在实验室规模的原型中进行评估，实验和建模工作的结合将揭示可能的退化机制和瓶颈，以促进合理的改进策略。该奖项反映了NSF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。

The efficient capture of carbon dioxide (CO2) from stationary emitters and ambient air is vital in meeting climate targets. However, the conventional thermochemical methods for CO2 capture are energy-intensive, cost-prohibitive, and fossil fuel-dependent. On the other hand, emerging carbon capture approaches driven by electrochemical reactions promise mild operating conditions, flexibility for coupling to intermittent renewable energy resources, and could accommodate the multi-scale nature of carbon capture needs due to their modularity. Nevertheless, the practical deployment of existing electrochemical carbon capture processes remains hindered by issues such as oxygen sensitivity and evaporative loss. Correspondingly, this project explores a new concept for carbon capture modulated by electrochemical stimuli. The concept involves the generation of low-volatility, air-stable CO2 sorbents at an electrode surface, followed by CO2 capture in an absorber unit and the subsequent CO2 release upon switching the polarity of the electrode. The goal is to understand and ultimately harness control over the thermodynamics, reaction kinetics, and transport properties of the model electrochemical system, utilizing a multi-modal toolkit of materials synthesis, characterization, and electroanalysis. The broader impacts involve education and mentoring activities from high school through graduate levels to prepare a young generation of engineers with an interdisciplinary skillset essential to solving humanity’s sustainability challenges, which include developing high school laboratory modules on carbon capture and integrating advances in separation methods and interfacial sciences into the university’s chemical engineering curriculum. The project aims to research an electrochemical interface composed of redox-tunable Brønsted base moieties that can undergo proton-coupled electron transfer (PCET) in non-aqueous electrolytes for the reversible (re)generation of air-stable CO2 sorbents. At the molecular level, the relationship between molecular structure, Brønsted basicity, and PCET energetics will be delineated to inform the rational design of carbon capture chemistry. At the material level, microporous electrodes will be synthesized to examine the interplay between electrode microstructure and the corresponding mass and charge transport behaviors. The impact of the electrolyte environment on the PCET and CO2 chemisorption kinetics will also be systematically investigated via (electro)analytical techniques. Finally, the CO2 separation concept will be evaluated in a bench-scale prototype, and a combined experimental and modeling effort will shed light on possible degradation mechanisms and bottlenecks to promote rationally motivated improvement strategies.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.