Trapped in the laboratory for nearly two decades, the ‘wonder material’ graphene has finally had its potential unlocked with the development of cost-effective quality CVD graphene films at an industrial scale.
Image Credit: General Graphene Corporation
Since being first discovered by Professors Andre Geim and Konstantin Novoselov in 2004, graphene has been hailed as a ‘wonder material.’ Just the thickness of a single atom, pristine graphene has been under the microscope in a seemingly endless cycle of theoretical experiments, all of which have demonstrated its extraordinary properties, including:
- Ultrathin (.345 nm).
- Flexible - Young’s modulus of 1 Tpa.
- Intrinsic tensile strength of 130 GPa (>200x stronger than steel).
- Thermal conductivity > 3,000 WmK (graphite is 2,000 WmK).
- Optical absorption of exactly πα ≈ 2.3% (i.e., transparent).
- Impermeable barrier to all gases.
- Room temperature electron mobility of 200,000 cm2/(V·s) (silicon is 1,400 cm2/(V·s)).
- Breakdown current density of 107 A/mm2 (copper is 1,000 A/mm2).
Simply put, graphene is the strongest, thinnest, and most conductive material known to man. Other properties include transparency, impermeability, as well as being chemically inert and biocompatible.
It has been said that the application potential of graphene has only been limited to the imagination; ideas have surfaced that it could enable an endless supply of clean water, batteries that could go through entire charging cycles in seconds and last for days – and even a space elevator.
It comes as no surprise that Geim and Novoselov were thus awarded the 2010 Nobel Prize for Physics.
A Troubling Dichotomy
Graphene has been almost exhaustively studied, maybe more so than any material in history. Yet, after two decades of investigation, a troubling dichotomy surrounds developments: while the hypotheses around graphene’s properties are very much true, they are also very misleading.
It is not possible to synthesize ‘pristine graphene’ at any scale under real-world conditions (at least not yet). Additionally, graphene production has proved to be complex and expensive. Once thought of having limitless commercial and technical potential, people have now become suspicious and believe that such promise is more of a fantasy than a reality.
Indeed, the surrounding hype has arguably led to more disappointment than satisfaction.
History is littered with fervently held ‘truths’ that were eventually proven to be not only misleading but also wrong (e.g., the Earth is flat, the Sun revolves around the Earth, stress causes ulcers, and so on). Yet, this is not the case with graphene.
Science has facilitated a deep study of graphene and the ability to identify it and understand its theoretical potential. Science alone cannot, however, help fulfill that potential.
The times we live in are complex and chaotic; it is not possible to know or predict everything. However, as time progresses, the inherent order in nature makes itself clear, and the chaos typically fades away when it does. Some people are able to see this, but the majority cannot.
The careers of Charles Darwin, Adam Smith, and Albert Einstein show that while they could not always explain it perfectly, they were fully aware of the order found in nature better than most.
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Einstein’s protégé, Richard Feynman, delivered an address to the National Science Teachers Association in April 1966 when he suggested students could be made to think the way scientists do — open-minded, curious and hold the element of doubt.
Throughout the lecture, he offered a definition of science, which he said was based on a number of stages: The evolution of intelligent life on planet Earth – creatures such as cats that play and learn from experience; The evolution of humans, who began communicating through language to exchange knowledge and preserve information for future generations.
Of course, erroneous knowledge could be passed down just as readily as correct knowledge, so an additional step was necessary. Galileo and others had some doubts about the so-called truth of what was passed down and started to probe ab initio, from experience, what the true situation was – as a result, science was born.
Science, as outlined by Feynman, enables humanity to clearly see the inherent order within the Universe – predicated on the fact we are open-minded, curious and willing to doubt what we already know.
Plenty of Room at the Bottom
In December 1959, Feynman delivered a speech to the American Physical Society entitled ‘Plenty of Room at the Bottom.’ Feynman stated that the central focus of the talk was “the problem of manipulating and controlling things on a small scale.”
It is often cited as the birth of nanotechnology, and it still provides researchers with important insights into better understanding the world around us – and it is extremely valuable when attempting to grasp a better understanding of graphene.
During his presentation, Feynman stated, “I am not afraid to consider the final question as to whether, ultimately – in the great future – we can arrange the atoms the way we want… What would happen if we could arrange the atoms one by one the way we want them? (Within practical limits, you can’t put them so that they are chemically unstable, for example).”
The material Feynman is describing clearly sounds like graphene, although it is merely the first of many such nanomaterials.
What could we do with layered structures that have the right layers? What would the properties of materials be if we could really arrange the atoms the way we want them? They would be very interesting to investigate theoretically. I can’t see exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on a small scale, we will get an enormously greater range of things we can do, due to the possible properties that such substances can have.
While in just a few years, today’s technology will be viewed as impractically crude, a man did walk on the Moon with technology more limited than what is found in today’s smartphones.
Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics. So, as we go down and fiddle around with the atoms down there, we are working with different laws, and we can expect to do different things.
Feynman’s ‘great future’ that he imagined has finally arrived. While this future is still in its nascent state – as is graphene – the capacity to arrange atoms one by one finally exists.
Introducing General Graphene
General Graphene was established with the focus of releasing graphene’s potential, furnished with a few clear (but subtle) truths:
- Graphene is not a ‘one size fits all’ material. Similar to metal alloys, it’s properties can be improved and manipulated to meet the demands of a specific application, and combining graphene with other materials often leads to remarkable improvements in the properties of the latter.
- Mass-producing graphene is not only a scientific problem; it is an engineering problem.
- The first step with any new material is developing the capacity to mass-produce effectively at lower costs. The term ‘industrial scale’ is synonymous with ‘lower cost.’
Graphene has been the source of considerable confusion for some time, and this results from the fact in two chemically identical but materially different varieties:
- ‘Top down’ graphene, which is from exfoliated graphite.
- ‘Bottom up’ graphene, which is synthesized via chemical vapor deposition (CVD).
Similarly, there are other forms of carbon, such as diamond and graphite, that are also chemically identical, but no one has ever mixed them up. While the two types of graphene are often classified generically as equal, and both deliver similar impressive properties, no one familiar with both types would ever mix them up.
Exfoliated graphite is a black powder, and though often categorized as a ‘film,’ each granule will typically measure less than a few microns thick and the standard unit of measure is kilograms or grams. By way of comparison, CVD graphene is a transparent, continuous film that can be measured in a few nanometers and the standard unit of measure is square meters or square centimeters.
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It has previously been established that the best quality graphene could be obtained via CVD with the application of a common laboratory ‘tube furnace.’ The process is extraordinarily simple. The closed quartz tube acts as the reaction chamber.
A catalytic metal substrate, typically copper or nickel foil, is positioned into the tube, and oxygen is purged to produce an inert atmosphere while the tube is heated to an extreme temperature (>1,000 °C).
Then, the introduction of a gaseous carbon (e.g., methane or CH4) is completed in trace amounts (i.e., parts per million) and dehydrogenated (the carbon separates from the hydrogen), eventually depositing itself on the catalytic metal foil, generating a continuous graphene film.
However, the CVD process has unfortunately been historically slow. Only tiny amounts of graphene can be generated due to the limited size of the quartz tube, each batch is a unique and isolated process, and it is extremely expensive.
To put it another way, graphene synthesized via conventional CVD methods is the complete opposite of a modern industrial process, which requires high-production yields, reproducible and consistent results, and low cost.
Scaling batch processes to a continuous production line presents a seemingly insurmountable challenge, but as with the majority of good innovations, simplicity was the key to overcoming the issues.
General Graphene was created with the main objective of converting CVD into an industrial-scale process. As previously noted, it was recognized this was the only appropriate path to attaining lower costs with the demands of commercialization.
The General Graphene Corporation now boasts a patented, proprietary atmospheric CVD process that has the capacity to manufacture high volume, consistent and high-quality graphene films in a roll to roll structure at lower costs. General Graphene is the only graphene manufacturer that does not use a quartz tube.
The method that General Graphene first demonstrated was conducted on a modular pilot production machine with further design and refinement occurring explicitly for scalability.
Measuring more than 21 m in length, the production machine as it stands can generate a 300 mm wide graphene film that can be customized to any length (and may be scaled easily to much wider widths).
The method can be run continuously, as energy consumption is significantly reduced at a steady state. Process inputs and outputs are almost identical, with the latter containing a trace amount of water vapor and CO2. No harsh chemicals are used in the process, and everything from production is biodegradable or recyclable.
Conclusively, graphene is far from being a ‘one size fits all’ material. General Graphene’s process facilitates the fine-tuning of graphene to bring out the best properties required for a given application.
General Graphene recognizes the fact it only offers half of the solution needed for the development of a particular application project – General Graphene understands graphene, but it's the commercial partners that understand the application.
Only through collaboration can the best solutions be developed to exploit the potential graphene offers, ushering in the next generation of products that graphene science has long promised. Application development is an ongoing process that necessitates patience but holds enormous promise when trying to unlock truly unique graphene solutions.
General Graphene is fast, focused and flexible because the company understands that the combination of cost and performance (rather than performance alone) must be synergized to promote innovation. If you are interested in unlocking graphene’s potential with General Graphene, contact a member of the team today.
This information has been sourced, reviewed and adapted from materials provided by General Graphene Corporation.
For more information on this source, please visit General Graphene Corporation.