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Converting Carbon Dioxide to Methane Now Possible With Rhodium


Using UV light, Duke University researchers managed to develop nanoparticles that act as a catalyzer while converting carbon dioxide into methane.

This new nanoparticle requires UV light as the UV light contains more energy than visible light. Scientist now look ways to proceed this reaction with natural light so the reaction can take place with less energy.

Chemists and researchers have been looking for a catalyst to reduce the energy needed for this reaction as the reaction can help reduce the carbon dioxide levels in the atmosphere. Not only that, but the reaction releases methane as a product, which is the source of many fuels.

Normally, such a reaction would result in a by-product called carbon monoxide, along with methane. Carbon monoxide is a toxic substance that results in the formation of ozone in the atmosphere, thus contributing to the global warming. According to the researchers, the absence of carbon monoxide makes this reaction even more green and efficient. Jie Liu, a Chemistry professor at Duke University said:

“The fact that you can use light to influence a specific reaction pathway is very exciting. This discovery will really advance the understanding of catalysis.”

The paper appeared on Nature Communications online on February 23th.

The nanoparticle, rhodium, is one of the rarest elements, yet it is a vital part of our technology and everyday lives. Rhodium is used as a catalyst due to its nature to speed up several industrial reactions. These reactions include the production of drugs, detergents, and nitrogen fertilizer. Rhodium is also used by some as a catalytic converter in vehicles to reduce the toxic pollutants.

Regarding this nanoparticle, Henry Everitt, a Physics professor at Duke and senior research scientist at the Army’s Aviation and Missile RD&E Center at Redstone Arsenal, AL, commented:

“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. For the last few years there has been a recognition that this property might be applied to catalysis.”

In Jie Liu’s lab, Xiao Zhang, a graduate student, was able to synthesize rhodium in the optimum nano size to absorb UV light. Normally, Zhang was forwarding this reaction by putting heat that is 300 degrees Celsius. The products of this reaction were carbon monoxide and methane as heating makes the reactants burn with oxygen in the air and form carbon monoxide. For the next experiment, Zhang used UV-light instead of heat, and only methane formed in the products. To explain the how they found this alternative reaction, Everitt commented:


“We discovered that when we shine light on rhodium nanostructures, we can force the chemical reaction to go in one direction more than another. So we get to choose how the reaction goes with light in a way that we can’t do with heat.”

The nanoparticles increase the efficiency and feasibility of the industrial reactions. Regarding this advantage, Zhang added:

“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, and if the selectivity is very high, you can also save time and energy by not having to purify the product.”

The next aim for the team is to be able to use this catalyst with sunlight, as it can increase the efficiency of reactions that proceed with solar power. Such advancement can contribute to the renewable energy industry.

Liu was very happy and hopeful with the results of their research:

“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. 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.”

[via eurekalert]

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