3D-printed single-atom catalysts make it easier

3D-printed single-atom catalysts make it easier

3D-printed single-atom catalysts make it easier

What if you could 3D print a substance that turns wastewater into fertilizer, converts CO2 become useful materials again and efficiently produce hydrogen from water?

And – above all – what if you could do it at a lower cost? All this is possible, but expensive.

Today, an international team of scientists has developed a simple method and cost effective technique for 3D printing “single atom catalysts”.

Like all catalysts, these substances make chemical reactions faster and less energy intensive.

But single-atom catalysts are particularly attractive because they are extremely efficient, meaning reactions can be carried out with even less energy and waste.

Single atom catalysts are not, quite, single atoms. Instead, they are individual metal atoms deposited on a substance – usually a tiny solid scaffold.

Because the metal atoms are dispersed and do not overlap, they can each do their job with maximum efficiency, turning reactant molecules into products.

“This unique advantage drives my research team to investigate this new type of catalyst,” says Professor Shizhang Qiao, Director of the Center for Energy and Catalytic Materials at the University of Adelaide and lead author of a paper describing research, published in Natural synthesis.

Until now, single atom catalysts were very difficult and expensive to manufacture. But Qiao and his colleagues have shown that it is possible to make them with a 3D printer, in just a few minutes.

Summary diagram
The manufacturing process for single atom catalysts. Credit: Xie, F., Cui, X., Zhi, X. et al. A general approach to 3D printed single atom catalysts. Nat. Synth (2023).

They used a 3D bio-printer to make the scaffold.

The printing ink included natural polymers and metals.

“Among these natural polymers, most of them are commercially available,” Qiao explains.

“It makes me believe that other researchers could easily pick up on this process.”

Once made, the Australian Synchrotron researchers used X-ray spectroscopy to show that the scaffolds really did contain single atoms.

Person at the synchrotron
Dr Bernt Johannessen on the Australian synchrotron X-ray absorption spectroscopy beamline. Credit: ANSTO

Qiao and his colleagues then tested the method by making an array of single-atom catalysts designed to convert wastewater nitrates into ammonia.

Ammonia is a crucial ingredient for fertilizers, pharmaceuticals and a range of other substances. It is also set to become a major energy player over the next three decades because it can help store hydrogen.

But there could be a number of other processes that single-atom catalysts can help facilitate.

“My research group used various electrocatalysts in different reactions,” says Qiao.

“For example, we have developed a new type of catalyst for the separation of water to produce hydrogen, the reduction of carbon dioxide to produce useful chemicals and fuel, an oxygen reduction reaction for fuel cells and oxidation of urea-rich wastewater.

“All of these applications are beneficial for renewable energy technology.”

The researchers believe that single-atom catalysts could be available to the chemical engineering industry within the next decade.

“By simplifying the way catalysts are made, this new technique has the potential to advance Australia’s status as a world leader in tackling the effects of climate change and help us lead new chemical manufacturing techniques that benefit society,” says Qiao.

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