Abstract
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.
Highlights
The electrocatalytic reduction of CO2 using renewable energy sources offers an attractive route to produce storable carbonneutral fuels.1,2 For this technology to become commercially viable, catalysts that promote the challenging multi-electron/-proton transfer reaction with minimal energy losses and high rate and selectivity need to be developed
We report a surface active-site engineering approach for modulating electrocatalytic CO2 reduction using the macrocycle cucurbit[6]uril (CB[6])
A notable shift of the carbonyl stretching mode from 1743 cm−1 in solution to 1737 cm−1 on the aqueous electrolytes.3−5 Gold (Au) surface further suggests an interaction between the carbonyl-lined portals of CB[6] with the gold surface, which is in line with previous reports
Summary
The electrocatalytic reduction of CO2 using renewable energy sources offers an attractive route to produce storable carbonneutral fuels. For this technology to become commercially viable, catalysts that promote the challenging multi-electron/-. On the other hand, has developed very effective catalytic systems that surpass the limits of scaling relationships Enzymes such as carbon monoxide dehydrogenase and formate dehydrogenase are able to reversibly interconvert CO2 at the thermodynamic potential with quantitative product selectivity at their precious-metal free active sites.− While details about their reaction mechanisms are still under debate, a hydrophobic active site cavity and the stabilization of intermediates by a highly specific second coordination sphere are believed to be crucial for their high activity as well as selectivity.. Other hosts such as pillararenes, cyclodextrins, and calixarenes typically rely on additional steps for electrode immobilization, which often afford increased distances between the host cavity and the surface.− Their ability to directly affect surface-bound species is thereby diminished It has been shown spectroscopically and by gravimetric measurements that CB[6] can be used as a highly porous solidstate adsorbent for gaseous CO2 with high selectivity over CO,. We employ surface-enhanced infrared absorption (SEIRA) spectroscopy combined with electrochemistry to investigate the behavior of CO2 within CB[6] on the Au surface during electrocatalysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
