A new generator converts CO2 into electricity.

Researchers at the University of Queensland have developed a pioneering nanogenerator that harnesses carbon dioxide (CO2) to generate electricity, marking a significant advancement in both carbon capture technologies and sustainable energy sources. 

Dr Zhuyuan Wang, the lead researcher, says the tiny generator integrates industrially familiar materials with advanced nanotechnology. 

“This nanogenerator is made of two components: a polyamine gel that is already used by industry to absorb CO2 and a skeleton a few atoms thick of boron nitrate that generates positive and negative ions,” he said. 

The polyamine absorbs CO2 and interacts with a nanostructured skeleton of boron nitride to facilitate ion separation.

The core mechanism that allows the nanogenerator to produce electricity is based on the differential movement of ions. 

“We’ve worked out how to make the positive ions much larger than the negative ions, and because the different sizes move at different speeds, they generate a diffusion current which can be amplified into electricity,” Dr Wang says. 

This process of ion transport is inspired by the natural and highly efficient energy conversion seen in biological systems. Natural ion transportation is much more efficient than traditional electron transport used in most power networks.

In laboratory tests, the researchers embedded the polyamine gel and boron nitrate into a hydrogel matrix, which is about 90 percent water. 

This mixture was then moulded into discs and small rectangles and placed in a sealed box filled with CO2. 

“When we saw electrical signals coming out, I was very excited but worried I’d made a mistake,” Dr Wang said. 

After verifying the results, the device's efficacy in generating power through CO2 absorption was confirmed.

The research group’s recently-published paper details the use of Nanosheet-Agarose Hydrogel (NAH) composite-based generators. 

These generators optimise ion separation within hydrogel channels filled with water, where CO2 adsorption triggers the release of oppositely charged ions. 

The design exploits the size disparity between large cationic and small anionic species released during CO2 adsorption, efficiently separating them due to the different ways they move through the nanoconfined spaces of the hydrogel matrix.

Director of the UQ research centre, Professor Xiwang Zhang, said the successful laboratory tests suggest two potential applications for the nanogenerator in the future.

“We could make a slightly bigger device that is portable to generate electricity to power a mobile phone or a laptop computer using CO2 from the atmosphere,” Professor Zhang said.

“A second application on a much larger scale, would integrate this technology with an industrial CO2 capture process to harvest electricity.”

The technology is being further refined and tested under the GETCO2 initiative, an ARC Centre of Excellence for Green Electrochemical Transformation of Carbon Dioxide, led by Professor Zhang at UQ.