It has been a fruitful year for the research and development of graphene applications, as this novel material continues to astonish researchers with its unique properties, enhancing the performance of coatings and solar cells.
Graphene is a single-layer sheet of carbon atoms arranged in a hexagonal lattice structure, forming a two-dimensional material with exceptional mechanical, electrical and thermal properties.
Graphene sheets are building blocks for other graphitic materials – they can be cut and folded into a spherical shape to make a carbon-60 fullerene molecule, rolled up to create carbon nanotubes, and further bonded on top of each other to make the bulk material graphite.
In addition to its applications in cutting-edge sensors, graphene is frequently utilised as an additive in protective coatings. The graphene forms a physical barrier that prevents corrosive elements from reaching the underlying metal surface.
The unique properties of graphene in coatings include impermeability to most gases and liquids, exceptional mechanical strength, the ability to maintain effectiveness at extremely low concentrations, and compatibility with existing coating systems.
In recent research published in Nature Physics, scientists detected, for the first time, electrons in graphene behaving like a nearly perfect quantum fluid.
The researchers, from the Indian Institute of Science (IIS) and National Institute for Materials Science in Japan, created ultra-clean samples of graphene and uncovered a surprising decoupling of heat and charge transport.
At the ‘Dirac point’ – a special feature in a material’s electronic band structure where the conduction and valence bands meet to form a linear energy-momentum relationship – graphene electrons flowed like an exotic liquid similar to quark-gluon plasma with ultra-low viscosity.
Arindam Ghosh, Professor at the IIS’s Department of Physics and one of the study’s authors, said it was amazing that there was so much to do on just a single layer of graphene, even after 20 years of discovery.
Aniket Majumdar, first author and PhD student at the Department of Physics, said: “Since this water-like behaviour is found near the Dirac point, it is called a Dirac fluid.
“[This is] an exotic state of matter which mimics the quark-gluon plasma, a soup of highly energetic subatomic particles observed in the particle accelerators at CERN.”
Closer to home, researchers at Monash University developed a new carbon-based material in September that they claim enables supercapacitors to store as much energy as traditional lead-acid batteries, while delivering power more rapidly than conventional batteries.
They achieved this by applying a rapid thermal annealing step to a graphite oxide precursor, resulting in supercapacitors that attain power densities as high as 69.2 kilowatts per litre, while also demonstrating fast-charging capabilities and excellent cycle stability.
Supercapacitors store charge electrostatically, rather than through chemical reactions, and a major challenge until now was that only a small fraction of the carbon material’s surface area was accessible.
Professor Mainak Majumder, Director of ARC Research Hub for Advanced Manufacturing with 2D Materials (AM2D) based in Monash’s Department of Mechanical and Aerospace Engineering, said the researchers had been able to unlock much more of that surface area by simply changing the way the material is heat-treated.
He said: “This discovery could allow us to build fast-charging supercapacitors that store enough energy to replace batteries in many applications, and deliver it far more quickly.”
Prof Majumder added that the key to the development lay in a new material architecture called multiscale reduced graphene oxide, which is synthesised from natural graphite.
Western Australian graphene supplier First Graphene has discovered that the addition of its functionalised graphene product to perovskite solar cells nearly doubled their efficiency and reduced production costs by up to 80 per cent.
The graphene-enhanced solar cells were developed in partnership with NSW-based Halocell Energy and the Queensland University of Technology, and have been shown to enhance light-absorbing performance, reducing manufacturing and materials costs.
First Graphene said the boosted performance was predominantly due to its graphene formulation being compatible with roll-to-roll dispersion technology, which eliminates traditional high-cost conductor materials (such as gold and silver) from cell production.
Last year, the company signed a two-year agreement to supply Halocell for use as a high-performance coating in its cells, noting that cells made with alternative carbon-based materials, such as graphene, have been widely found to outperform conventional silicon cells in low artificial light conditions and indoor environments.
It added that perovskites could provide lower manufacturing, processing and energy costs, and their energy payback period could be as low as six weeks, compared to about two years for silicon cells.
Michael Bell, Managing Director at First Graphene, stated that the partnership with Halocell is fostering competitive Australian innovation with a global reach.
Bell said: “We’re pleased with the progress Halocell has made applying our PureGraph to its perovskite solar cell development, not only through our R&D collaboration but now in a commercial setting.”
Another Perth-based graphene company, ASX-listed Sparc Technologies, announced in August that it had achieved up to a 60 per cent reduction in corrosion with its graphene-enhanced water-based coatings, compared to commercially available products.
The water-based coatings market is currently experiencing rapid growth, driven by environmental concerns and regulations aimed at reducing volatile organic compounds (VOCs). Sparc’s development represents an expansion beyond its flagship product, which is primarily targeted at solvent-based coatings.
Water-based coatings are non-toxic, low-odour, have reduced VOCs, and allow for easier application and cleanup, making them more attractive than conventional solvent-based products that utilise fossil fuel-derived organic solvents.
The global market for water-based epoxy coatings is projected to grow from $1.6 billion in 2022 to $2.9 billion by 2029 – a compound annual growth rate of 8.9 per cent – while the wider anti-corrosion coatings market is predicted to reach $43 billion in the same time frame.
