Carbon dioxide emissions are the primary cause of global warming, with energy generation being a major source. If carbon dioxide could be harnessed to produce energy instead, it would be a major step towards a Net Zero future.
A collaboration between the research teams of Prof. Xiwang Zhang at the University of Queensland and Prof. Huanting Wang from Monash University has led to a breakthrough in generating electricity from carbon dioxide (CO2).
In biological systems, selective transport of positive and negative ions efficiently converts food into energy and drives signalling within and between cells. The researchers have copied this approach by building a proof-of-concept generator that uses CO2 and water as a feedstock. It uses nanosheets of boron nitride embedded in a hydrogel matrix.
The generator operates under alkaline conditions, where CO2 and H2O react with amine groups on the nanosheets to produce HCO3-. This moves freely across the hydrogel device, while the positive charges produced by the reaction remain anchored to the immobile nanosheets embedded in the hydrogel. This movement of the negative ions, but not the positive ones, establishes a charge gradient, generating an electrical current. Over time, as the system absorbs more CO2, the pH gradually shifts towards acidic conditions, which ultimately signals that the generator is ‘full’. It can then be regenerated by restoring the pH to the alkaline range, enabling the system to restart the energy conversion process. This regeneration process releases the CO2, which can either be reused in the rejuvenated generator or captured by calcium to lock it away as calcium carbonate. In this second case, more CO2 can be taken up by the generator.
Electron microscopy at our Monash University facility was instrumental in understanding the nano- and micro-structures of the generator and will continue to help the team as they work to improve the efficiency of their process.
Scanning (left) and transmission (right) electron microscope images of the boron nitride nanosheets.
This technology has the potential to transform CO2 from a problem into a valuable resource. Two potential applications are currently envisaged by the researchers. “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.
“A second application on a much larger scale, would integrate this technology with an industrial CO2 capture process to harvest electricity,” Prof. Zhang said.
The development of the nanogenerator will continue through the ARC Centre of Excellence for Green Electrochemical Transformation of Carbon Dioxide (GETCO2). The team was a Eureka Prize finalist for their invention.
Z. Wang et al., Nature Communications 2024
DOI: 10.1038/s41467-024-47040-x
March 10, 2025
