Host-Guest Chemistry Meets Electrocatalysis: Cucurbit[6]uril on a Au Surface as a Hybrid System in CO2 Reduction.

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Ly, Khoa H 
Heidary, Nina 
Szabó, István 
Földes, Tamás 

The rational control of forming and stabilizing reaction intermediates to guide specific reaction pathways remains to be a major challenge in electrocatalysis. In this work, we report a surface active-site engineering approach for modulating electrocatalytic CO2 reduction using the macrocycle cucurbit[6]uril (CB[6]). A pristine gold surface functionalized with CB[6] nanocavities was studied as a hybrid organic-inorganic model system that utilizes host-guest chemistry to influence the heterogeneous electrocatalytic reaction. The combination of surface-enhanced infrared absorption (SEIRA) spectroscopy and electrocatalytic experiments in conjunction with theoretical calculations supports capture and reduction of CO2 inside the hydrophobic cavity of CB[6] on the gold surface in aqueous KHCO3 at negative potentials. SEIRA spectroscopic experiments show that the decoration of gold with the supramolecular host CB[6] leads to an increased local CO2 concentration close to the metal interface. Electrocatalytic CO2 reduction on a CB[6]-coated gold electrode indicates differences in the specific interactions between CO2 reduction intermediates within and outside the CB[6] molecular cavity, illustrated by a decrease in current density from CO generation, but almost invariant H2 production compared to unfunctionalized gold. The presented methodology and mechanistic insight can guide future design of molecularly engineered catalytic environments through interfacial host-guest chemistry.

surface active-site engineering, electrocatalytic CO2 reduction, host-guest chemistry, supramolecular catalysis
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ACS Catal
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American Chemical Society (ACS)
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Christian Doppler Forschungsgesellschaft (unknown)
European Research Council (682833)
Royal Society (NF160054)
Engineering and Physical Sciences Research Council (EP/L027151/1)
European Commission (658360)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (706425)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (701192)
Christian Doppler Research Association, the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development, the OMV Group, EU ERC Consolidator grant ‘MatEnSAP’, Starting Grant ‘BioNet’, Royal Society Newton International Fellowship, European Commission for Marie Curie Fellowships, EPSRC, DFG, Deutsche Forschungsgemeinschaft/German Research Foundation