Creating Sustainable Fuel Using a Novel Approach

Researchers from Ohio State University have shown that carbon dioxide, a greenhouse gas, can be efficiently transformed into methanol, a type of liquid fuel. Their discovery was published in Nature Catalysis.

For years, chemists have been attempting to convert waste molecules into high-value materials. Scientists worldwide are now investigating ways to use electricity to speed up the procedure.

To accomplish this operation, cobalt phthalocyanine (CoPc) molecules were equally dispersed over carbon nanotubes, which have special electrical characteristics similar to graphene. An electrolyte solution covered their surface, allowing CoPc molecules to absorb electrons and convert carbon dioxide into methanol when an electrical current was sent through them.

Researchers used in-situ spectroscopy to visualize the chemical process and saw those molecules change themselves into either methanol or carbon monoxide, which is not the desired product. They discovered that the reaction route is determined by the environment in which the carbon dioxide molecule reacts.

The Ohio State University professor of chemistry and biochemistry Robert Baker, a co-author of the study, noted that by fine-tuning this environment by manipulating the distribution of the CoPc catalyst on the carbon nanotube surface, carbon dioxide was up to eight times more likely to produce methanol. This discovery could boost the efficiency of other catalytic processes and broadly impact other fields.

When you take carbon dioxide and convert it to another product, there are many different molecules you can make. Methanol is definitely one of the most desirable because it has such a high energy density and can be used directly as an alternative fuel.

Robert Baker, Study Co-Author and Professor, The Ohio State University

Although turning waste molecules into valuable chemicals is not new, scientists could not often observe the reaction until recently—a critical insight that would have allowed them to refine and enhance the procedure.

However, the team has made significant progress in understanding the intricate process using specialized methods and computer modeling. According to Quansong Zhu, the study’s lead author and a former Ohio State Presidential Scholar, who made the difficult measurements that were essential to the finding, the researchers’ use of a novel form of vibrational spectroscopy in this study allowed them to see how molecules react on the surface.

We could tell by their vibrational signatures that it was the same molecule sitting in two different reaction environments. We were able to correlate that one of those reaction environments was responsible for producing methanol, which is valuable liquid fuel.

Quansong Zhu, Study Lead Author and Former Presidential Scholar, The Ohio State University

A deeper investigation also revealed that these molecules were directly interacting with supercharged particles known as cations, which accelerated methanol synthesis.

This discovery is crucial to developing a more effective method of producing methanol, but according to Baker, further investigation is required to determine what else these cations allow.

Baker added, “We are seeing systems that are very important and learning things about them that have been wondered about for a long time. Understanding the unique chemistry that happens at a molecular level is really important to enabling these applications.”

Aside from being a low-cost fuel for vehicles such as planes, automobiles, and cargo vessels, methanol created from renewable electricity might be used for heating and power generation, as well as to progress future chemical discoveries.

“There’s a lot of exciting things that can come next based on what we’ve learned here, and some of that we’re already starting to do together. The work is ongoing,” Baker stated.

Conor L. Rooney and Hailiang Wang from Yale University, Hadar Shema and Elad Gross from Hebrew University, and Christina Zeng and Julien A. Panetier from Binghamton University are the other study authors.

The study was supported by the National Science Foundation and the United States–Israel Binational Science Foundation (BSF) International Collaboration.

Journal Reference:

Zhu, Q., et. al. (2024) The solvation environment of molecularly dispersed cobalt phthalocyanine determines methanol selectivity during electrocatalytic CO₂ reduction. Nature Catalysis. doi:10.1038/s41929-024-01190-9