Rhodium nanocubes heated by ultraviolet light allow CO2-to-methane reactions to be catalyzed at room temperature. Photo by Chad Scales/Duke University
Feb. 23 (UPI) -- Scientists at Duke University have developed a new method for catalyzing the conversion of carbon dioxide into methane, a component of many alternative fuels. The reaction is bolstered by the presence of rhodium nanoparticles and ultraviolet light.
Rhodium is known to accelerate, or catalyze, a variety of reactions used for industrial processes, but the energy boost offered by the rare earth metal can prove too much -- shortening catalyst times and yielding unwanted chemical byproducts.
Duke researchers found they could eliminate these unwanted results by shrinking bits of rhodium into nanoparticles, using a process called plasmonics, and blasting them with ultraviolet light.
"Effectively, plasmonic metal nanoparticles act like little antennas that absorb visible or ultraviolet light very efficiently and can do a number of things like generate strong electric fields," Henry Everitt, an adjunct professor of physics at Duke, said in a news release. "For the last few years there has been a recognition that this property might be applied to catalysis."
When scientists passed carbon dioxide and hydrogen through rhodium nanocubes heated to 300 degrees Celsius, chemical reactions yielded equal parts methane and carbon monoxide. But when an ultraviolet lamp was used to heat the nanocubes, the reactions produced mostly methane.
"If the reaction has only 50 percent selectivity, then the cost will be double what it would be if the selectively is nearly 100 percent," Zhang said. "And if the selectivity is very high, you can also save time and energy by not having to purify the product."
Researchers believe their findings -- detailed in the journal Nature Communications -- are likely applicable to other important chemical reactions.
