Getting to net-zero carbon emissions is going to take all sorts of tactics, including switching to renewable energy and finding new methods of carbon sequestration, or collecting and preventing carbon dioxide from reaching the atmosphere.
Another promising solution is carbon recycling, or using electrochemistry to power a CO2 reduction reaction that turns carbon dioxide into carbon monoxide, the feedstock for many valuable chemicals. Not only does the process use up excess carbon dioxide, it reduces the need for chemical precursors derived from fossil fuels.
While researchers have studied the carbon dioxide reduction reaction for several decades, it is still not feasible at an industrial scale. But Matthew Gebbie, the Conway Assistant Professor in chemical and biological engineering at the University of Wisconsin-Madison, hopes that he can use a National Science Foundation CAREER award to fine-tune the electrolytes used in carbon dioxide reduction reactions to improve their speed and efficiency.
Electrochemical devices are composed of two electrodes—a cathode and an anode—separated by an electrolyte, or an ion-rich substance that’s usually a liquid. At the surface of these electrodes, ions from the electrolyte tend to collect and self-assemble, creating a region called the electric double layer. While most prior research in electrocatalysis focused primarily on how the structures and properties of electrodes influence reactivity, recent research by Gebbie and others has shown that the structures and concentrations of ions in electrolytes can cause the electric double layer to grow thinner or thicker and switch from ordered to disordered. That has major impacts on reactivity.
In his CAREER Award project, Gebbie and his students will investigate how collective ion assembly at the electric double layer influences the carbon dioxide reduction reaction and the electrochemical properties of interfaces. In particular, Gebbie and his students want to figure out how to use electrolytes to tune the double layer environment to promote the carbon dioxide to carbon monoxide reaction and limit other competing reactions, like hydrogen evolution, which has been one of the major difficulties in optimizing electrochemical carbon dioxide recycling.
Gebbie says that working with graduate student Beichen Liu and postdoctoral scholar Wenxiao Guo over the last couple of years has made this work possible. “They really collaborated with me to build on our electrocatalysis capabilities and benchmark our data against what had already been reported,” he says. “And Guo brings to the table a unique ability to do in situ surface-sensitive Raman spectroscopy of electrochemical interfaces. Bringing together emerging concepts and tools from colloid and interface science to evaluate our hypotheses and reveal new insights into nanostructured electric double layers could make a big impact in the field of catalysis that extends well beyond carbon dioxide electrochemistry.”
For the outreach element of his CAREER Award, Gebbie and his students are developing a water splitting challenge for public and student outreach. By using different kinds of electrolytes, like Gatorade or pickle brine, they will show how these substances can affect reactivity of electrochemical devices, which participants will monitor using a multimeter. People who conduct the experiment can log their experiments in a database and compare their outcome to others.
They also plan to develop interactive electrocatalysis course modules for high school teachers that will build the skills to demonstrate and explain the concepts in their own classrooms. “I think I’m going to learn a ton in terms of my own education and outreach skills,” says Gebbie, who at one point considered becoming a high school teacher himself. “A big part of why I’m doing this job is not just to pursue research, but also teaching and outreach. I am very excited and appreciative to have the opportunity to launch a five-year project aimed at integrating research and outreach to drive towards long term impact in electrochemistry and sustainability.”
Featured image caption: Graduate student Beichen Liu (left) and postdoctoral scholar Wenxiao Guo (right) are key collaborators on Matthew Gebbie’s (center) NSF CAREER Award project. Credit: Joel Hallberg.