Selective CO Reduction to Ethylene Using Imidazolium-Functionalized Copper.

Electrochemical CO reduction is a promising approach to obtain sustainable chemicals in energy conversion. Improving the selectivity of CO reduction toward a particular C product such as ethylene remains a significant challenge. Herein, we report a series of imidazolium hexafluorophosphate compounds as surface modifiers for planar Cu foils to boost the Faradaic efficiency (FE) of ethylene from 5 to 73%, which is among the highest reported using polycrystalline Cu. The modified electrodes are convenient to prepare. The structure-function study demonstrates that varying the alkyl or aromatic substituents on the imidazolium nitrogen atoms has significant effects on the morphology of the deposited films and the product selectivity of CO reduction. Experimental FE, FE, ln(FE/FE), and ln(FE/FE) values show generally linear relationships with FE while using different imidazolium modifiers, suggesting that factors governing proton reduction may also be directly related to both overall C generation and ethylene selectivity. This work presents an effective and practical way in tailoring the active sites of metallic surface for selective CO reduction.