Electrolysis of ethylene to ethylene glycol paired with acidic CO2-to-CO conversion

초록

Electrochemical conversion of CO2 into CO, ethylene, and other valuable chemicals is a promising method for carbon capture and utilisation. However, when carried out in an alkaline or neutral media, (bi)carbonate formation leads to low atom efficiency in the electrocatalytic process. In contrast, acidic conditions enable >80% CO2 utilization, but there is a need to lower full-cell voltage. In this work, we paired the acidic cathodic CO2-to-CO reaction with acidic anodic ethylene-to-ethylene glycol (C2H4-to-EG) conversion for the first time. For the selective oxidation of ethylene to EG, we employed a homogeneous redox mediator ruthenium-polyoxometalate (Ru-POM) with gold-modified electrodes for the first time to facilitate the redox cycle. This resulted in enhanced selectivity and stability, achieving a faradaic efficiency (FE) of 83% for EG. At the cathode, a porous nickel single-atom catalyst drives the conversion of CO2 into CO in an acidic electrolyte with an FE of 97%. The paired system operates at a full-cell voltage of 3.1 V, compared to 3.3 V for a reference system using the oxygen evolution reaction. The demonstrated system offers a promising route for reducing carbon emissions with high atom efficiency.

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