This study outlines a process that is both electrical and chemical in nature. It is therefore referred to as electrochemical. This study looks at the conversion of carbon dioxide CO2 directly into ethanol by using a new carbon-copper catalyst. This electrochemical process simultaneously lowers atmospheric CO2 and provides an avenue to store renewable energy in the form of ethanol. The carbon-cooper catalyst had a high Faraday efficiency (FE), which is a measure of how easily an electron is transferred within an electrochemical reaction. However, the FE decreased significantly when Copper oxide and large Copper cluster impurities started to accumulate.
Capturing carbon and even its conversion into fuels are viable alternatives that target to decrease atmospheric CO2 levels while producing energy. There are a variety of issues with current systems, which essentially boil down to efficiency issues. In order to combat these issues, the catalyst must be modified. The researchers suggest that the dispersion of the metal particles over the catalyst could affect the catalytic mechanism. This would in turn lead to a better or worse FE.
Synthesis of Catalyst
Complex multi-step process that results in a mixture that is uniform in molecular structure.
At -0.3 Volts, there was no ethanol production observed, at -0.4 Volts there was ethanol production with a FE of 15%, at -0.6 Volts there was ethanol production with a FE of 91%. This is the highest ever reached as known by the researchers. This catalyst was able to maintain a FE of 91% at -0.7 V over a 16hr span and was incredibly stable. It was also found that the rate at which CO2 was turned into ethanol decreased as the amount of Copper in the catalyst increased. As the amount of Copper increases past 0.8 wt%, it changes the mechanism by which the electrochemical process occurs and thus decreases the Faraday Efficiency. The results indicate that the initial dispersion of the Copper atoms play a vital role in increasing the FE. Future studies are required to understand the exact mechanism.
This study looked at different carbon-copper catalysts prepared by starting with a copper-lithium mixture. It has been noted to have to maintain a FE of 91% at -0.7 V over a 16hr span, which is unprecedented. The dispersion of the copper atoms was found to have a large effect on the FE and thus the electrochemical mechanism and subsequently the rate of reaction.