This Carbon Dioxide-Guzzling Nanogenerator Hints at Carbon Negative Power for Future Devices
"Until now CO₂ has been seen as a problem to be solved," says corresponding author Xiwang Zhang, "but it can be a resource for the future."
Researchers from the University of Queensland and Monash University have developed a nanogenerator that, they say, is carbon negative — absorbing atmospheric carbon dioxide and turning into an admittedly-small amount of electricity.
"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," explains Zhuyuang Wang, PhD and lead author, of the team's creation. "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."
"“When we saw electrical signals coming out, I was very excited but worried I'd made a mistake," Wang continues. "I double-checked everything, and it was working correctly so I started dreaming about changing the world using this technology. This technology goes further than being carbon neutral — it consumes CO₂ as it generates energy. At present we can harvest around one per cent of the total energy carried intrinsically by gas CO₂ but, like other technologies, we will now work on improving efficiency and reducing cost."
Tested in a best-case environment — a sealed box pumped full of carbon dioxide — the nanogenerator was able to output 80mV ±10mV with a peak current of 150nA ± 20nA. While that's not much on its own, the generators can also be stacked to boost their output: a four-generator series or parallel network could hit 280mV and 400nA, while a prototype 50-generator vertical stack reached 5V — enough to light an off-the-shelf LED with a 1.6V forward operating voltage and a 1mA current draw, albeit briefly.
"Upon lighting the diode," the team admits, "the induced voltage dropped below the operating voltage but was rapidly recovered once the external circuit was disconnected. Only a minor reduction in the voltage was observed after four cycles of charge and discharge."
"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," Xiwang Zhang, director of the University of Queensland's Dow Center for Sustainable Engineering Innovation and corresponding author on the paper, suggests of the device's potential.
"A second application on a much larger scale, would integrate this technology with an industrial CO₂ capture process to harvest electricity. We want to realize the value in a problematic greenhouse gas and to change the perception of CO₂. Until now CO2 has been seen as a problem to be solved but it can be a resource for the future."
The team's work has been published in the journal Nature Communications under open-access terms.