Researchers have developed a chemical system they say efficiently carries out the first step in creating syngas, or synthesis gas.
A mixture of carbon monoxide, carbon dioxide and hydrogen, syngas can be burnt and used as a fuel source. According to Biofuel.co.uk, syngas has 50 percent the energy density of natural gas.
For decades, researchers have tried to develop an efficient and scalable method to lower the oxidation state of carbon dioxide.
The new co-catalyst system uses inexpensive carbon-based nanofiber materials to convert carbon dioxide to carbon monoxide -- a starting material used to synthesize fuels.
"I believe this can open a new field for the design of inexpensive and efficient catalytic systems for the many researchers already working with these easily manipulated advanced carbon materials," said Amin Salehi-Khojin, a professor of mechanical and industrial engineering at the University of Illinois-Chicago and principal investigator on the study published in Nature Communications.
Salehi-Khojin previously used an ionic liquid to catalyze the reaction's first step, and silver for the final reduction to carbon monoxide. Although the process was more efficient than single-catalyze systems, silver is expensive, so the scientists went to work to see if they could replace it with a relatively new class of metal-free catalysts.
As a substitute for the silver, they chose carbon nanofibers doped with nitrogen. However, a close examination revealed that it was not the nitrogen that was acting as the catalyst in the new system.
"It was the carbon atom sitting next to the dopant that was responsible," said graduate student Mohammad Asadi.
The finding was surprising, as was the discovery that the new co-catalyst system was even more efficient than the previous one.
According to Bijandra Kumar, one of two first-authors of the paper, they "uncovered the hidden mechanism" of the reaction, and in doing so "opened up a lot of options for designing inexpensive and efficient catalyst system for carbon dioxide conversion."
Going forward, the researchers hope the study will help pave the road toward not only commercially viable production processes for syngas, but gasoline developed from carbon dioxide.