Electrocatalytic reduction of CO2 to fuels would provide a synthetic sustainable way to convert renewable energy sources to transport fuels, however, large overpotentials and inability to control product selectivity are significant barriers to application. Understanding the observed experimental selectivity to methane and ethylene during CO2 reduction on Cu electrodes remains an open question. We have performed a systematic density functional theory (DFT) study to evaluate the activation barriers for the elementary steps for CO2 electroreduction on the Cu(111) surface. The potential-dependent barriers incorporate the role of water through the explicit addition of 1 or 2 water molecules. We find that CO reduction to COH or CHO intermediate is the key selectivity step for production of methane/ethylene over methanol. Furthermore, the water faciliates a H-shuttling mechanism for O-H bond formation that can reduce the barriers and plays an important role in the preferred pathway. Our work provides a new path for CO2 electroreduction on Cu(111) that matches recent electrokinetic experiments. I will also report on our current efforts to understand CO2 reduction on low-coordinated Cu structures, in particular Cu(100), along with our efforts to understand the trends in CO2 product selectivity across various metal electrodes.

Understanding CO2 electroreduction on Cu electrodes through first-principles modeling

249th National Meeting (2015)

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Understanding CO2 electroreduction on Cu electrodes through first-principles modeling<br />

Understanding CO₂ electroreduction on Cu electrodes through first-principles modeling<br />