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

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.