Nanogenerator absorbs CO2, produces electricity

Researchers at The University of Queensland (UQ) have built a generator that absorbs carbon dioxide (CO₂) to make electricity. Development of the small, proof-of-concept nanogenerator was led by Dr Zhuyuan Wang, from the UQ Dow Centre for Sustainable Engineering Innovation, and described in the journal Nature Communications.

“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,” Wang said.

“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 to power light bulbs or any electronic device.

“In nature and in the human body, ion transportation is the most efficient energy conversion — more efficient than electron transportation, which is used in the power network.”

The two components were embedded in a hydrogel which is 90% water, cut into 4 cm discs and small rectangles and then tested in a sealed box pumped full of CO₂. According to Wang, “When we saw electrical signals coming out, I was very excited but worried I’d made a mistake.

“I double-checked everything, and it was working correctly so I started dreaming about changing the world using this technology.”

Wang said the technology goes further than being carbon neutral, as it consumes CO₂ as it generates energy. “At present we can harvest around 1% of the total energy carried intrinsically by gas CO₂,” he stated, “but like other technologies, we will now work on improving efficiency and reducing cost.”

Following the success of the laboratory tests, Dow Centre Director Professor Xiwang Zhang said there are 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,” he said.

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

The development of the nanogenerator will continue through the ARC Centre of Excellence for Green Electrochemical Transformation of Carbon Dioxide (GETCO₂), where Zhang serves as Director. He said the goal of the research is to “realise the value in a problematic greenhouse gas and to change the perception of CO₂” from a problem to be solved to a resource for the future.

Image courtesy UQ.