It is now 10 years since the Nobel Prize winners Andre Geim and Konstantin Novoselov published the first1 of a series of seminal papers that triggered a sharp rise in the level of graphene research efforts worldwide. Fuelled by public (for example, European Commission, UK and Korean governments) as well as private investments (for example, Samsung, IBM, Nokia), research on graphene has produced a substantial body of scientific knowledge, accompanied by a surge of publications and patent applications. The past 6–7 years have seen a steady, worldwide emergence of private ventures focused on the manufacturing and commercialization of graphene and graphene-based materials, with 44 companies currently active (Mark Rahn from MTI Venture, talk given at Graphene: Commercialisation and Applications, Univ. of Manchester, 12–13 June 2014) and a range of these materials commercially available.
Nevertheless, there are only a few graphene-based products that have reached the market, such as the tennis racket by Head, the battery strap by Vorbeck, the oil-drilling mud by Nanochem or the phone touch screen by Samsung. These products represent an initial market entry rather than the first, full commercial wave of graphene products. The size of the graphene market was estimated2 to be around US$12 million in 2013, indicating that so far we are still in a phase of research and development, in which the market is dominated by sales of raw graphene materials. The market projections for the next 5–10 years, however, indicate significant expansion and revenue increase. An increase in graphene demand should drive up production scale and drive down costs, resulting in a shift from material sales to a market dominated by sales of graphene-based components, systems and products.
The steep rise in graphene application patents further supports the realization of an industrial graphene market in the upcoming years3. Figure 1 shows the comparison of the patent landscape of different materials. The number of graphene patents has increased significantly more steeply than for the other benchmark materials, including silicon (Fig. 1, inset).
Progress in the commercialization of graphene can be assessed by looking at the growth of demand-driven graphene production (rather than production capacity) and benchmarking it against that of carbon fibres and carbon nanotubes. The time of the first step-increase in the number of patent applications can be used as a proxy for the time when a critical mass of research and development activity was first reached. This can be set as the 'time zero' for commercialization — that is, around 1970 for carbon fibres, around 2001 for carbon nanotubes and around 2009 for graphene (Fig. 1). The production of carbon fibres reached 4,600 tonnes per annum (tpa) in 19784, that is, within 8 years from time zero; the production of carbon nanotubes reached 4,600 tpa in 20115, within 10 years from time zero. Data about graphene production are less readily available and rely on estimates. But the estimated production of 120 tpa in 2015 and 1,200 tpa in 2019 (Z. Ma, personal communication on results from 2014 Lux Research survey of graphene suppliers) — within 6 and 10 years, respectively, from time zero — may suggest a slower growth in the demand and production of graphene than for carbon fibres and carbon nanotubes.
This indication is in clear contrast with the increase in the number of organizations developing graphene applications or the unprecedented rise in patent applications, and is a typical example of the complex trends that accompany the commercialization of any emerging technology. In an attempt to shed some light, this Commentary will identify and discuss the key factors that could affect the speed of commercial deployment of graphene in the next 5 years.
Factors that may slow adoption
There has been significant progress in the development of graphene manufacturing methods, and graphene production is starting to experience the need or demand for quality, quantity, reliability and price, in other words standardization and industrialization. There are diverse methods to produce different types of graphene material. For conciseness, we will focus on three main types of graphene product and related production methods: graphene films, graphene oxide (GO) flakes and graphene nanoplatelets (GNPs).
Monolayer GO flakes can be obtained by chemical exfoliation of graphite6. These GO flakes are heavily functionalized by oxygen-containing groups such as epoxy, hydroxyl, carbonyl and carboxylic acid groups, and they form very stable dispersions in water. But they are electrically insulating; to restore electrical conductivity, they have to be reduced thermally, chemically or by irradiation.
Similarly to GO flakes, GNPs can be manufactured as a free-standing, powder-like material and in large quantities. This makes GNPs suitable for large-volume dispersion in paints, coatings, composites, films, adhesives, lubricants and functional fluids, where GNPs act as a multifunctional additive. In contrast to GO flakes, GNPs are electrically conductive and predominantly hydrophobic. They are mostly obtained by exfoliating graphite7, in a batch process that allows the manufacture of large quantities of material, which tends to vary in thickness and composition, with a percentage of unexfoliated graphite often present in the final product. GNPs can also be produced by bottom-up synthesis, using a gas-phase, self-assembly process that does not involve graphite and can be tuned to confer a partial hydrophilic character to GNPs to aid dispersion8.
Graphene films are currently produced by chemical vapour deposition on metallic substrates. Chemical vapour deposition is an industrially relevant manufacturing method because it can produce large-area films that can be transferred onto a variety of substrates9, 10, 11. Batch or continuous production processes can be envisaged for the synthesis of graphene films. Batch processes are industrially very relevant, and are used, for example, in the production of light-emitting diodes (LEDs), transistors and solar cells. Batch production of graphene is currently at a 6-inch wafer scale, with 12-inch graphene wafers that might become available in the next couple of years. On the other hand, continuous or semi-continuous production processes that could meet larger demand for graphene films are currently under development, and should be available in the coming years. The choice of production process will depend on the required graphene film properties and the targeted application, which in turn will define the volume and price requirements. It is worth mentioning that there are fewer companies producing graphene films than those producing GNPs. A possible reason could be the longer time-to-market of graphene films. Furthermore, in 2013 Graphenea estimated the market size for graphene films to be considerably smaller than that for the bulk material (GO, GNPs), in a 1:4 ratio.
Production volume. Limited material availability can potentially slow down the commercial adoption of graphene. A large and growing number of variations does, however, exist for the production methods described, and more than 40 companies are currently producing and processing graphene. Achieving volume production in the next 2 to 5 years seems possible. A production capacity of a kilotonne per year for GO flakes and GNPs, and a million square metres per year for graphene films, should be adequate to support short-term product development and commercialization. The focus of graphene manufacturers is therefore rapidly shifting towards improving batch-to-batch consistency and costs. Consistency is crucial for industrial applications and depends on process repeatability, but also on graphite quality in the case of GO flakes and GNPs produced by exfoliation.
Cost. This is another critical parameter that could speed up or slow down the adoption of graphene in volumes. Costs have already come down considerably since graphene was first introduced in the research community. Even at a laboratory scale, in the past 2 years the price per square centimetre and per gram has dropped to a third and to a quarter of its starting price, respectively.
The material cost required to enable commercialization is also application-dependent, and a higher initial material cost is likely to promote adoption in applications that exploit multiple graphene properties. A slower decrease in the cost of graphene will delay the deployment in price-sensitive, large-volume products and in applications looking at graphene for material replacements, cost savings or medium-level improvement in a single performance parameter. However, a great improvement in a single parameter or a unique combination of properties should be able to redefine the price point of some products and, within certain limits, make the cost of graphene irrelevant.
Resistance by current technologies. Another significant market barrier that could affect the speed of adoption of graphene is the resistance produced by incumbent materials and technologies. If graphene was to replace an existing material, there would certainly be resistance by existing suppliers in an attempt to slow down or prevent a switch to a new material. For instance, the high transparency and electrical conductivity of graphene make it an ideal candidate for transparent electrodes in touch screens and displays. At present, indium tin oxide (ITO) is the industry standard. A well-established ITO supply chain results in optimized performance and competitive price. These constitute an effective entry barrier for graphene in this market, unless a specific property of graphene (for example its flexibility) makes the price comparison with ITO only marginally relevant.
Storage and transport. As the graphene industry matures, storage and transport will become an increasingly important aspect of the graphene supply chain, affecting both cost and availability, and hence the speed of industry adoption. The transport of graphene films is safe and relatively easy, because films are laid, stored and shipped on top of substrates. For GO flakes and GNPs, however, the decision of whether to handle graphene in wet (for example in water) or dry form during manufacturing, processing and distribution will affect costs and complexity of distribution. Because GO is stored in dispersed form in water, it is safe to transport. In the case of highly dilute dispersions, however, the issue of transporting mainly water questions the efficiency and economics of shipments. This could be overcome by supplying GO in dried form (as films that are from 100 nm to 100 μm thick) or as 'intermediate' products, where GO has been incorporated into a matrix material, such as polymer matrices. GNPs are similar to GO flakes: storage in wet form is convenient for safety and practical reasons, given that GNPs form an extremely low-density and fine powder, which requires large storage volumes and is hard to contain to prevent human exposure. But most graphene product manufacturers will buy graphene predispersed in polymers or solvents of their choice, thus requiring the wetted graphene to be dried before dispersion. This is time- and energy-consuming. The alternative option of distributing large volumes of graphene as a dry powder is impractical owing to the low material density. It is also unfeasible as many composites and product manufacturers do not allow dry nanomaterial powders in their premises because of health and safety concerns.
Health and safety. Uncertainty on health and safety aspects, and excesses of caution, can potentially slow down the industrial uptake of graphene. At present, there are no specific health and safety regulations related to graphene. Furthermore, there is a lack of toxicological investigations and standardized health and safety studies on the various families of graphene, whose properties and impact on health and safety may vary with the production process. In Europe, the safety of nanomaterials is regulated by the REACH Regulation12, according to which manufacturers and importers of nanomaterials at quantities of 1 tonne or more per year must register the substance. For small graphene manufacturers, reaching a production of 1 tonne or more per year will incur registration costs, posing an additional market barrier. On the other hand, some nanomaterials such as carbon black and synthetic amorphous silica have been commercialized for decades. For example, the yearly production of carbon black exceeds 9 million tonnes (ref. 13). In addition, we are exposed to ultrafine particles in our everyday lives and even at some workplaces where processes generate ultrafine dust14. Therefore, as long as the correct risk management measures are implemented at the workplace, where the risk of exposure is the highest for workers at the production scale, it should not hinder the adoption of graphene. Moreover, risk can also be reduced in the supply chain by offering intermediate products.
Factors accelerating adoption
The key to success will not rely only on the production of economically scalable graphene but in the ability to adapt the material to the requirements of the industrial application, in selecting the right markets (niche applications) and in the availability of intermediate materials.
Intermediate materials. Establishing the benefits and the availability of intermediate graphene products is crucial to move from a materials market to a components market and aid the adoption of graphene. A huge effort has been made by the academic community to investigate the laboratory-scale integration of bulk graphene and to produce intermediate materials. In many cases, however, the results have been obtained using processes that are not industrially relevant, and it is now time to move towards pilot-scale studies with industrially compatible methods. One example of a laboratory-scale study could be the mixing of bulk graphene with polymeric matrices using organic solvents. There are many limitations when using solvents, such as an increase in production costs, environmental impact (need to eliminate the solvent) and low volumes of processed materials, and the scale-up to pilot scale could prove more challenging than originally expected. There are not yet sufficient, systematic and consistent data that illustrate the impact on the properties from incorporating graphene in a polymer matrix. The generation of such data in accordance with DIN, ASA or ISO standards will stimulate industry interest and expedite commercial deployment.
Customer-led integration. The processing of graphene into forms suitable for customers to integrate into final products is another factor that can significantly accelerate the uptake of graphene. In the case of graphene films, the integration will be extremely challenging, and two main integration options are envisaged: graphene is manufactured and integrated by the end user; or graphene is supplied on a substrate and integrated into the end-user process.
Furthermore, the integration complexity will vary depending on the application. In the case of GNPs, the availability of graphene in forms that are familiar to the chemical and polymer industry will be essential to advance material validation and adoption. Aqueous and organic solvent solutions, as well as concentrated suspensions and slurries, provide an effective intermediary for the introduction of graphene into paints, films and coating formulations. Similarly, master batches and the predispersion of graphene in polymers can greatly aid the introduction of graphene into composite materials and polymer products.
Niche applications. Focusing on niche applications that present low barriers to adoption and meet compelling unmet technology needs could also be key to early commercial success. Examples of market entry opportunities for graphene include:
- DNA sequencing: nanopores in graphene could enable the sequencing of DNA15, 16.
- Membranes and filtration system for water purification: graphene could provide both chemical and mechanical filtering.
- Thermal management applications: graphene-containing metal, ceramic and polymer matrix composites could provide thermal interface materials and heat spreaders17.
- Photodetectors: graphene could enable high-responsivity detectors for light harvesting18 and ultrafast detectors for digital photon counting in medical imaging.
- Organic LEDs (OLEDs) and displays: graphene-based transparent conductors could add flexibility in OLEDs19, displays and touch-screen applications.
- III–V semiconductor growth: graphene could be used as a substrate for growing high-quality semiconductor materials such as gallium nitride (GaN)20.
- Anticorrosion coatings: graphene-enabled anticorrosion coatings could provide a replacement for carcinogenic chromate-based primers in steel and aluminium materials.
- Novel lubricants: graphene could be a dry, thin-film lubricant used in low-wear and high-precision components such as ball bearings, watch mechanisms, sealed mechanical systems and engine components optimized for harsh environments.
Figure 2 provides a high-level overview of the wide range of applications envisaged for graphene films and GO or graphene flakes.
Standardization. Finally, given the very diverse range of graphene materials, an effort to standardize the definition of different types of graphene and related materials will accelerate the process of adoption and commercialization of graphene by reassuring potential adopters about the nature and quality of these materials.
Reflecting on the trends observed for previous emerging technologies, we can predict a number of evolutions over the commercial lifetime of graphene.
To begin with, we can expect a transition from a market initially dominated by niche, low-volume and high-margin applications to a mature market with an increased number of large-volume but potentially lower-margin applications. This is similar to what happened with carbon fibres. Also in the case of graphene, the diversity of manufacturing methods and the related performance differentiation is likely to lead to a situation where, over time, certain graphene materials will be more commoditized than others, with certain types of graphene preserving a high price over a much longer time period. Conversely, variation in price sensitivity across industries is likely to lead to a split of the graphene manufactured by the same method and produced in different grades, according to parameters such as size, purity, electrical or thermal conductivity. The different grades will exhibit a varying price, in line with the requirements and price flexibility of the target industry sectors.
Finally, a consolidation in the graphene supply industry might occur, as often observed when a new material industry reaches maturity (as seen for carbon nanotubes and carbon fibres). It could lead to the appearance of 'one-stop-shop' suppliers capable of producing multiple formats of graphene using a range of production methods. Consolidation may also result in the merging of multiple manufacturers with similar processes, hence creating fewer and larger suppliers of a certain type of graphene material. These developments will determine the ability to preserve market shares and margins by dominant graphene manufacturers. They should not affect material availability and the speed of commercialization of graphene-based products.
Progress towards the commercialization of graphene has been considerable, especially in the past 5 years. The extraordinary growth in the number of organizations developing graphene applications and in the number of patents filed, may suggest an opportunity for a further acceleration of graphene commercialization. On average, however, the commercialization of an advanced material can take up to 20 years. It took 20 years to develop applications for polyethylene beyond insulation and radar housing, and Dupont needed 20 years to exploit Kevlar (polymer fibre) profitably in lightweight armour. Judging from the progress to date, the resources mobilized worldwide and the level of industry awareness, graphene might be on track to become a commercial reality in less than 20 years from the first attempts at commercialization.
The availability of material with the right volume, quality and cost to meet the requirements of industrial applications will be key to rapid graphene commercialization. The ability of both suppliers and adopters of graphene to identify initial applications where the use of graphene provides compelling benefits beyond cost competitiveness will also play a crucial role. The speed of industrial uptake will also be influenced by factors such as the optimization of supply-chain logistics (for example, material storage and transportation), the availability of intermediaries (for example, dispersions, solutions, master batches, pre-transferred films) to accelerate integration into products and systems, clear standards, and a robust framework for health and safety regulation.
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