Rice University Scientists Turn Greenhouse Gas Into Environmentally Friendly Liquid Fuel

“Formic acid is an energy carrier. It’s a fuel-cell fuel that can generate electricity and emit carbon dioxide — which you can grab and recycle again," said Wang in a press release announcing the research. “It’s also fundamental in the chemical engineering industry as a feedstock for other chemicals, and a storage material for hydrogen that can hold nearly 1,000 times the energy of the same volume of hydrogen gas, which is difficult to compress. That’s currently a big challenge for hydrogen fuel-cell cars.”

The new system is a result of Wang and the team from Rice's Brown School of Engineering's charge to find useful technologies that can turn greenhouse gases into products. The team was able to reach an energy conversion efficiency of around 42% with this test. 

The researchers own developments made this possible

Chuan Xia, lead author of the study, which was published in Nature Energy, said his development of a two-dimensional bismuth catalyst and the development of a solid-state electrolyte that removes the need for salt to get a reaction made the conversion of the greenhouse gas into something more environmentally friendly possible.  Once the process was perfected, the scientists worked with Brookhaven National Laboratory to watch the process in progress. 

"X-ray absorption spectroscopy, a powerful technique available at the Inner Shell Spectroscopy (ISS) beamline at Brookhaven Lab's National Synchrotron Light Source II, enables us to probe the electronic structure of electrocatalysts in operando -- that is, during the actual chemical process," said co-author Eli Stavitski, lead beamline scientist at ISS. "In this work, we followed bismuth's oxidation states at different potentials and were able to identify the catalyst's active state during carbon dioxide reduction."

Big picture impacts

The lab was able to generate formic acid continuously for 100 hours with little in the way of degradation of the reactor's components.  The scientists see their work having a bigger impact on the environment. 

"The big picture is that carbon dioxide reduction is very important for its effect on global warming as well as for green chemical synthesis," Wang said. "If the electricity comes from renewable sources like the sun or wind, we can create a loop that turns carbon dioxide into something important without emitting more of it."