Too much levels of greenhouse gases in the atmosphere is a silent climate killer.

Early in June, researchers in Hawaii reported that the atmosphere contains 400 parts per million (ppm) of carbon dioxide (CO2) — surpassing the symbolic limit.

Although passing the threshold only means that current global warming will continue, there may still be hope to alleviate the crisis.

In order to reduce the levels of global carbon dioxide emissions, scientists have developed an efficient way to convert the greenhouse gas CO2 into much more useful materials.

Finding An Efficient Catalyst

Led by Professor Beatriz Roldan Cuenya, a team of experts from Ruhr-Universität Bochum (RUB) in Germany discovered a catalyst that performs extremely selective conversion of CO2 into ethylene.

Ethylene is an important material for the chemical industry, and it is often used in agriculture to force the ripening of fruits. When turned into a polymer, ethylene becomes polyethylene.

Scientists say catalysts often used for the electrochemical conversion of CO2 into useful chemicals are not efficient enough because the materials do not possess high selectivity.

The materials produce too many unwanted side products and too little ethylene.

Now all of that has changed, as RUB scientists made a breakthrough discovery.

Hemma Mistry, a PhD student and one of the researchers of the study, used copper films treated with hydrogen or oxygen plasmas as catalysts.

Using these plasma treatments, Mistry changed the properties of the copper surface, making it less rough and oxidizing the material. She varied the plasma parameters systematically until she reached the optimal surface properties.

The best catalyst boasts a higher ethylene production rate than conventional copper catalysts. It also performs in a highly selective manner. This allows the amount of unwanted side products to be considerably reduced.

"It's a new record for this material," says Roldan Cuenya.

Why Is Mistry's Plasma Treatment Successful?

Researchers were determined to figure out why the plasma treatment had worked so well. Through synchrotron radiation, RUB scientists analyzed the chemical state of the copper film during the catalysis of the reaction.

With the help of these measurements, Mistry, Cuenya and their other colleagues discovered the cause of the higher ethylene selectivity. As it turns out, it was due to the positively charged copper ions located at the catalyst surface.

It had been supposed at the beginning that copper can only exist in a metallic form under certain reaction conditions. However, the findings of the team now disproved this assumption. The details were further proven by extra microscopic analysis.

Cuenya says the results of their study open up new possibilities for the design of catalysts on the nanoscale with selectivity and specific activity.

Details of the study are published in the journal Nature.

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