Spatial-confinement induced electroreduction of CO and CO 2 to diols on densely-arrayed Cu nanopyramids.

The electroreduction of carbon dioxide (CO ₂ ) and carbon monoxide (CO) to liquid alcohol is of significant research interest. This is because of a high mass-energy density, readiness for transportation and established utilization infrastructure. Current success is mainly around monohydric alcohols, such as methanol and ethanol. There exist few reports on converting CO ₂ or CO to higher-valued diols such as ethylene glycol (EG; (CH ₂ OH) ₂ ). The challenge to producing diols lies in the requirement to retain two oxygen atoms in the compound. Here for the first time, we demonstrate that densely-arrayed Cu nanopyramids (Cu-DAN) are able to retain two oxygen atoms for hydroxyl formation. This results in selective electroreduction of CO ₂ or CO to diols. Density Functional Theory (DFT) computations highlight that the unique spatial-confinement induced by Cu-DAN is crucial to selectively generating EG through a new reaction pathway. This structure promotes C-C coupling with a decreased reaction barrier. Following C-C coupling the structure facilitates EG production by (1) retaining oxygen and promoting the *COH-CHO pathway, which is a newly identified pathway toward ethylene glycol production; and, (2) suppressing the carbon-oxygen bond breaking in intermediate *CH ₂ OH-CH ₂ O and boosting hydrogenation to EG. Our findings will be of immediate interest to researchers in the design of highly active and selective CO ₂ and CO electroreduction to diols.
Competing Interests: There are no conflicts to declare.
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