We all know that the carbon dioxide (CO2) produced by burning fossil fuels is one of the worst greenhouse gases being emitted into our atmosphere. But did you know that CO2 could also be put to work in the opposite direction as a potential energy source? A team of researchers from the University of Illinois at Chicago (UIC) are working on just that idea. They say they have developed a new system that could create syngas (an early stage of synthetic natural gas) or even synthetic gasoline out of carbon dioxide. Their research was published this week in the journal Nature Communications.

The work is in its early stages, but so far the team has been able to efficiently and inexpensively convert carbon dioxide into carbon monoxide (CO), which is already one of the primary components of syngas. Co-lead author Amin Salehi-Khojin, a professor of mechanical and industrial engineering, said in a press release that he believes "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."

Converting CO2 to CO is nothing new, but to date it has been accomplished through a two-step process using the same catalyst during both stages. In a switch, the researchers used two different catalysts during the process, something they called a "co-catalyst system." Salehi-Khojin had already accomplished this in previous research using an ionic liquid for the first step and silver for the second.

But as the press release points out, "silver is expensive." Creating a truly efficient co-catalyst system requires coming up with a cheaper, metal-free alternative, which was the focus of the new research. Salehi-Khojin and his colleagues turned to inexpensive and easily produced carbon nanofibers, which they "doped" with nitrogen. They thought the nitrogen would be the key to the process, but they were surprised to find that it was actually the carbon that drove the chemical reaction that converted CO2 into CO. Not only that, it accomplished the task in a more efficient manner than silver. Salehi-Khojin said the discovery gives the team "enormous freedom" to study advanced carbon materials in the next phase of their work.

UIC research scholar Bijandra Kumar, the paper's other co-lead author, echoed this, saying their discovery has "opened up a lot of options for designing inexpensive and efficient catalyst system for carbon dioxide conversion." He said they may next be able to use ultrathin sheets of carbon graphene and dope them with nitrogen or other atoms to develop even more efficient systems.

Work on this discovery will continue, and the researchers say they hope it will one day lead to commercially viable new processes to produce syngas or synthetic gasoline from CO2.

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