Carbon nanomaterials from CO2
Materials such as carbon nanotubes, nanofibres and graphene are typically produced from hydrocarbons or graphite at very high temperatures. An innovative EU-funded research project, 'Unique nanocarbons from critically opalescent solutions' (UNCOS), is developing a synthesis method using carbon dioxide (CO2) at room temperature. The method relies on the formation of carbon nanoparticles by dissociation of critically opalescent CO2. Scientists are also investigating graphene production by processing in supercritical CO2 of a carbonised monolith obtained from a copolymer. Work in the first project period concentrated on characterising the stability of critically opalescent CO2 over time. The team demonstrated maintained opalescence for more than 24 hours in a 10-ml-volume reactor charged with CO2. Scientists also demonstrated the ability to dope the system with potential catalysts and mix the feedstock, temporarily changing the critical conditions but quickly re-establishing critical opalescence. Researchers then sought reproducible dissociation of critically opalescent CO2 with varying parameters in order to control the yield and physicochemical properties of the produced carbon nanomaterials. They achieved dissociation of critical CO2 to produce spherical carbon nanoparticles without the use of a catalyst. The team is now focusing on increasing reproducibility in order to control yield and upscale synthesis. In addition, they are exploring the use of supercritical CO2 to produce graphene layers. Close collaboration with external stakeholders, including carbon nanomaterial producers and existing technology providers, is helping ensure that prototype testing and characterisation is carried out with deliverables in mind. Work has already led to four publications in peer-reviewed scientific journals. The market for carbon nanomaterials is huge. Development of a low-cost and relatively simple synthesis method will have major benefits for industry and the EU economy.
Keywords
Carbon, nanomaterials, synthesis techniques, critically opalescent, supercritical CO2
