(450h) Activity and Selectivity Trends on Bimetallic Thin Films for Electrochemical Carbon Dioxide Reduction

Utilizing carbon dioxide (CO₂) as a feedstock for fuels and industrial chemicals is ideal owing to its natural abundance and the desire to reduce atmospheric concentrations of this greenhouse gas. The ability to electrochemically reduce CO₂ to these value added products has been demonstrated under moderate conditions (ambient temperature, pressure and in aqueous solutions) [1], yet the current state of electrocatalyst technology is not sufficiently advanced to the point that CO₂ reduction devices have become technologically relevant. At the present time, copper is the only transition metal shown capable of producing high proportions of attractive products, including methane, ethylene and ethanol [2]; albeit at very high overpotentials and with limited product tunability. It is of great importance to overcome these current limitations and develop electrocatalysts with high activity and good selectivity towards practical fuels and industrial chemicals.

In this work, we have developed bimetallic electrocatalyst thin films by electron beam evaporation. Their activity and selectivity are investigated towards CO₂ electroreduction in our three-compartment electrochemical cell that allows for excellent liquid and gaseous product detection [3]. We target certain bimetallic arrangements, including phase segregated systems, overlayers and near surface alloys. These configurations allow us to capitalize on ensemble and/or ligand effects at the electrocatalyst surface [4] with the goal of targeting further reduced (> 2 electron) CO₂ reduction products at high Faradaic efficiencies. By correlating thin film characterization before and after testing with results of electrochemical measurements, we draw surface structure-activity trends among this class of materials. Detailed understanding of these trends can be leveraged by the electrocatalysis community to move beyond pure copper based systems for electrochemical CO₂ reduction.

References

[1] Hori, Y., Modern Aspects of Electrochemistry, 42 (2008) Springer, New York, 89-189.

[2] Kuhl, K., Hatsukade, T., Cave, E., Abram, D., Kibsgaard, J., Jaramillo, T., Journal of the American Chemical Society, 40 (2014) 14107-14113.

[3] Kuhl, K., Cave, E., Abram, D., Jaramillo, T., Energy & Environmental Science, 5 (2012) 7050-7059.

[4] Rodriguez, J., Goodman, W., Journal of Physical Chemistry, 95 (1991) 4196-4206.