Collaborative Research: CAS: Carbene-Containing Ligands on Cu and Cu3N Nanocubes: Access to Stable and Selective Electrolysis for CO2 Reduction

在化学系化学催化项目的支持下，康涅狄格大学的He和Ung教授以及布朗大学的Sun教授正在设计用于选择性电化学激活二氧化碳(CO2)的新型杂化材料。该团队将利用合成聚合物来覆盖和保护铜基催化剂，从而使所产生的混合材料对于二氧化碳电还原产生增值碳氢化合物产品更加坚固和高效。利用可再生电力将二氧化碳转化为有用的化学产品很可能是可持续发展的一个重要组成部分。这个合作项目将包括来自两所大学的本科生、研究生和研究生研究人员，并将利用每个小组在聚合物、纳米材料、有机金属、表面科学和电化学方面的专业知识。该项目的成果将通过联合会议、课程、本科生研究活动和外展活动向理工科学生传播。PI正在与新英格兰南部地区的当地高中和外展项目合作，以吸引学生进入STEM(科学、技术、工程和数学)领域的研究和潜在的职业道路。在化学系化学催化项目的支持下，康涅狄格大学的何教授和吴教授以及布朗大学的孙教授正在研究新的铜基纳米立方体，这些纳米立方体带有合成聚合物配体，旨在稳定和选择性地电减少二氧化碳。这一提议的中心假设有两个：i)将铜基纳米立方体与合理设计的合成聚合物结合，以防止电还原过程中的颗粒间结合和表面腐蚀；ii)疏水聚合物配体，以控制纳米立方体的微环境，提高纳米立方体的选择性。以N-杂环卡宾(NHCS)封端的聚合物配体将通过稳定的NHC-Cu键固定在铜、氮化铜(Cu3N)和核壳结构的Cu/Cu3N纳米立方体上。这些纳米立方体具有最大的(100)表面暴露，可以有效地促进C-C偶联并形成C2+烃产品。聚合物NHC配体将通过控制聚合物链长和疏水性来平衡纳米立方体表面附近的局部质子浓度，以实现最大限度地催化质子辅助二氧化碳还原为C-C偶联产物，并最大限度地减少质子还原反应。用原位光谱和显微镜研究了聚合物接枝铜和铜纳米立方体的铜-NHC键的稳定性和结构完整性。聚合物链长相关的扩散性能将被定量测量，并与铜和Cu3N纳米立方体的催化性能相关联。活性和高效的聚合物NHC-铜纳米立方体用于二氧化碳电还原的成功展示还允许更广泛地解决所有其他阴极纳米催化剂的长期稳定性问题，以提高电还原的可持续性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemical Catalysis program in the Division of Chemistry, Professors He and Ung at the University of Connecticut and Professor Sun at Brown University are designing new hybrid materials for selective electrochemical activation of carbon dioxide (CO2). The team will utilize synthetic polymers to coat and protect copper-based catalysts, allowing the resulting hybrid materials to be more robust and efficient for CO2 electroreduction to yield value-added hydrocarbon products. The use of renewable electricity to convert CO2 to useful chemical products is likely to be an important component of sustainability. This collaborative project will involve undergraduate, graduate, and postgraduate researchers from two universities, and will utilize each groups’ expertise in polymer, nanomaterial, organometallic, surface science, and electrochemistry. The results obtained from this project will be disseminated to science and engineering students through joint meetings, courses, undergraduate research activities, and outreach activities. The PIs are collaborating with local high schools and outreach programs in the southern New England region to attract students into studies and potential career paths in STEM (science, technology, engineering and mathematics) fields.With the support of the Chemical Catalysis program in the Division of Chemistry, Professors He and Ung at the University of Connecticut and Professor Sun at Brown University are studying new Cu-based nanocubes functionalized with synthetic polymer ligands toward stable and selective electroreduction of CO2. The central hypothesis of this proposal is twofold: i) the incorporation of Cu-based nanocubes with rationally designed synthetic polymers to prevent interparticle coalescence and surface corrosion during electroreduction, and ii) hydrophobic polymer ligands to control the microenvironment of nanocubes and improve the selectivity of nanocubes. Polymer ligands terminated with N-heterocyclic carbenes (NHCs) will be anchored on Cu, copper nitride (Cu3N) and core-shell Cu/Cu3N nanocubes through stable NHC-Cu bonds. Those nanocubes have maximum (100) surface exposure to efficiently promote C-C coupling and form C2+ hydrocarbon products. Polymer NHC ligands will balance the localized proton concentration nearby the surface of nanocubes through control over polymer chain lengths and hydrophobicity to achieve maximum catalytic proton-assisted CO2 reduction to C-C coupling products and minimize proton reduction reaction. The Cu-NHC bond stability and the structural integrity of polymer-grafted Cu and Cu3N nanocubes will be probed using in situ spectroscopies and microscopies. The polymer chain length dependent diffusion properties will be quantitatively measured and correlated to the catalytic performance of Cu and Cu3N nanocubes. The successful demonstration of the active and efficient polymer NHC-Cu nanocubes for CO2 electroreduction also allows tackling more broadly the long-term stability issues of all other cathodic nanocatalysts to improve the sustainability of electroreduction.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.