Reusing CO2: Scientists are closer to converting it to clean energy

Nature emits carbon dioxide (CO2) as part of many different natural processes. Plants are known to take them in as a necessary ingredient in photosynthesis, and it benefits the Earth in a lot of different ways, such as accelerating plant growth and food production. Although the planet’s CO2 levels are currently near record lows throughout history, there is still plenty of it to go around, since humans contribute to CO2 emissions as well.

But while CO2 may be beneficial to the environment, there is evidence to support the notion that human CO2 emissions could be more useful if converted into other things like carbon monoxide (CO) instead. Now a team of scientists may have finally found a working solution to this issue.

A report on the newly formulated method noted that it was developed by researchers at the U.S. Department of Energy‘s (DOE) Brookhaven National Laboratory (Brookhaven Lab). It is said that they were able to find a new electrocatalyst that has the ability to convert CO2 to CO efficiently. The researchers shared the details of their study recently in the journal Energy & Environmental Science.

According to Eli Stavitski, one of the scientists at Brookhaven Lab and an author on the paper, it is well-known that there are many ways to use CO.

“You can react it with water to produce energy-rich hydrogen gas, or with hydrogen to produce useful chemicals such as hydrocarbons or alcohols,” he explained.

“If there were a sustainable, cost-efficient route to transform CO2 to CO, it would benefit society greatly.”

By using conventional methods of trying to convert CO2 to CO, scientists found that traditional catalysts just aren’t very effective. And it is said that the main reason for this is the presence of a competing reaction, which is called the hydrogen evolution reaction (HER). It ends up taking precedence over the CO2 conversion reaction, so any attempt to initiate it ultimately fails.

There are ways to prevent HER from happening, and thereby convert CO2 directly into CO, but they require the use of so-called noble metals like gold and platinum. These are indeed quite effective, but in practice can be very expensive. The researchers found a breakthrough by using single atoms of nickel in place of these noble metals.

Haotian Wang, a Rowland Fellow at Harvard University and a corresponding author on the study, stated, “Nickel metal, in bulk, has rarely been selected as a promising candidate for converting CO2 to CO.” And one of the reasons for it is that it performs HER quite well, and even reduces the rate of CO2 conversions dramatically seemingly at random.

“Another reason is because its surface can be easily poisoned by CO molecules if any are produced,” he added.

And so the method devised by the researchers relied on single atoms instead.

“Single atoms prefer to produce CO, rather than performing the competing HER,” said Stavitski, “because the surface of a bulk metal is very different from individual atoms.”

The researchers also resorted to using a sheet of graphene to help tune the nickel atoms as catalysts and suppress HER. They scanned an electron probe over the sample in order to visualize discrete nickel atoms on the graphene sheet properly.

As of this time’s writing, the scientists have concluded that their method is indeed an effective way of converting CO2 into CO, and that it is a major step forward for recycling the gas for usable energy and chemicals. Their next act is to apply their findings in the real world, first by finding a way to scale their method of using their single atom catalyst while improving its efficiency and performance all at the same time, bringing back the natural order of things.

Read more about carbon dioxide-related issues at CarbonDioxide.news.

Sources include:

BrightSurf.com

ScienceDaily.com