Researchers at Duke University have developed tiny nanoparticles that help convert carbon dioxide into methane using only ultraviolet light as an energy source according to the 23rd February paper published in Nature Communications.
Rhodium nanoparticles are the answer to the long search of for an efficient, light-driven catalyst to power the reaction.
Despite being one of the rarest elements on Earth, rhodium plays a surprisingly important role in our everyday lives. Small amounts of the metal are used to speed up or “catalyze” a number of key industrial processes, including those that make drugs, detergents and nitrogen fertilizer, and they even play a major role breaking down toxic pollutants in the catalytic converters of our cars.
Rhodium accelerates these reactions with an added boost of energy, which usually comes in the form of heat because it is easily produced and absorbed. However, high temperatures also cause problems, like shortened catalyst lifetimes and the unwanted synthesis of undesired products.
Not only are the rhodium nanoparticles made more efficient when illuminated by light, they have the advantage of strongly favouring the formation of methane rather than an equal mix of methane and undesirable side-products like carbon monoxide. This strong “selectivity” of the light-driven catalysis may also extend to other important chemical reactions, the researchers say.
“The fact that you can use light to influence a specific reaction pathway is very exciting,” said Jie Liu, the George B. Geller Professor of Chemistry at Duke University. “This discovery will really advance the understanding of catalysis.”
In the past two decades, scientists have explored new and useful ways that light can be used to add energy to bits of metal shrunk down to the nanoscale, a field called plasmonics.
“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,” said Henry Everitt, an adjunct professor of physics at Duke and senior research scientist at the Army’s Aviation and Missile RD&E Center at Redstone Arsenal, AL. “For the last few years there has been a recognition that this property might be applied to catalysis.”
Now the team plans to test whether their light-powered technique might drive other reactions that are currently catalyzed with heated rhodium metal. By tweaking the size of the rhodium nanoparticles, they also hope to develop a version of the catalyst that is powered by sunlight, creating a solar-powered reaction that could be integrated into renewable energy systems.
“Our discovery of the unique way light can efficiently, selectively influence catalysis came as a result of an on-going collaboration between experimentalists and theorists,” Liu said. “Professor Weitao Yang’s group in the Duke chemistry department provided critical theoretical insights that helped us understand what was happening. This sort of analysis can be applied to many important chemical reactions, and we have only just begun to explore this exciting new approach to catalysis.”
Having found a catalyst that can do this important chemistry using ultraviolet light, the team now hopes to develop a version that would run on natural sunlight, a potential boon to alternative energy, which could help reduce the growing levels of carbon dioxide in our atmosphere by converting it into methane, a key building block for many types of fuels.
This research was supported by the National Science Foundation (CHE-1565657) and the Army Research Office (Award W911NF-15-1-0320). Additional support was provided by Duke University’s Katherine Goodman Stern Fellowship, the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program and the Center for the Computational Design of Functional Layered Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award # DE-SC0012575.
Source: Duke University
