Rhodium Photocatalyst Speeds Conversion of CO2 to Methane

Car Catalytic Converter Parts | Adam J | Shutterstock.com

Researchers discovered a way to transform CO2 into methane, using nanoparticles as a catalyst and ultraviolet light as an energy source. This technique could help combat climate change by removing CO2 from the atmosphere at the site of production (fossil fuel processing).

A catalyst shortens the duration of a transformation by increasing the rate of a reaction. Catalysts are mainly used in industry for their selectivity: a catalyst is selective if its action is specific. The evolution of the products during heating depends on the catalyst used.

#Duke researchers used rhodium as a photocatalyst for converting CO2 into methane.Click To Tweet

Photocatalysis consists of triggering, under the action of solar or artificial light radiation, the degradation of mainly organic materials. Photocatalysis is often proposed as a solution for a multitude of industrial inefficiencies and has a wide range of applications: air-purification, destruction of nitrogen oxides and volatile organic compounds (VOCs), sterilization, self-cleaning materials, and water purification.

Nanoparticles as Photocatalyst to Favor Methane Formation

Long sought-after by chemists, a photocatalyst that helps to transform CO2 into methane has been discovered by a team of researchers at Duke University.

Chad Scales | Flickr | Duke University

In a paper published online yesterday in the journal Nature Communications, researchers demonstrated how they improved selective properties of rhodium (Rh) nanoparticles to favor the formation of methane in carbon dioxide hydrogenation reactions.

“The fact that you can use light to influence a specific reaction pathway is very exciting.” said Jie Liu, chemistry professor at Duke University. “This discovery will really advance the understanding of catalysis.”

Improving the already excellent catalytic properties of Rh nanoparticles, researchers simultaneously reduced the activation energy which enhanced selectivity to produce methane, unfavorable product in carbon dioxide hydrogenation reactions. Without illumination, a mix of carbon monoxide and methane are produced. Mildly illuminated, however, Rh nanoparticles almost exclusively favor methane formation.

Rhodium is a rare precious metal, and one the most expensive metals. Extracted as a by-product, the global production of rhodium was barely 28 metric tons in 2014. Other than jewelry, it’s a strategic material that’s indispensable for many industries because of its strong catalytic properties.

This technique, if developed to run on sunlight, as the team hopes, could play a major role in removing excess CO2 from the atmosphere. As an added bonus, the production of methane, the green fuel of tomorrow, could be an environmental and economic boon.

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