Graphene Manufacturing FAQs 
by General Graphene Corporation

Graphene is an ultrathin allotrope of carbon (diamond and graphite are the other common allotropes of carbon).  It consists of a single layer of sp2-bonded carbon atoms with each atom bound to three neighbors in a honeycomb structure.

Single atom thick graphene is sometimes called monolayer graphene or single-layer graphene and abbreviated as 1LG. Bilayer graphene consists of two well-defined stacked graphene layers (2LG). Few layer(s) graphene consists of three to ten well-defined stacked graphene layers (FLG).

Graphene may be synthesized from a gaseous carbon source at high temperatures using a process known as chemical vapor deposition (CVD). Another method uses a chemical process acids and heat to exfoliate graphite to produce graphene in a powder form. These graphene powders include graphene oxide (GO), a compound of carbon, oxygen and hydrogen) reduced graphene oxide (rGO), a compound with less oxygen and more carbon than GO; graphene nanoplatelets (GNP) short stacks of platelet-shaped graphene sheets that are identical to those found in the walls of carbon nanotubes, but in a planar form. Other carbon materials closely related to graphene include fullerenes (also known as “Bucky balls”) graphene quantum dots (GQD) and carbon nanotubes.

To understand what CVD graphene is, it is important to understand the definition of CVD. Chemical Vapor Deposition (CVD) is a process involving the high-temperature activation of gaseous hydrocarbons (e.g., methane) in the presence of a catalytic substrate, typically a copper or nickel foil. The subsequent chemical reactions deposit a thin, stable carbon lattice on the catalyst surface.

The key properties of graphene are that it is strong, flexible, electrically conductive, thermally conductive, optically transparent, and impermeable.

Graphene is the strongest (200-300 times stronger than steel at 130GPa), most elastic (Youngs modulus of 1 TPa), most electrically conductive (electron mobility of 200.000 cm²/V/s), thermally conductive (~5300/W/m^-1 K^-1). It is also optically transparent (absorbs 2.3% light per layer) and impermeable.

Graphene’s unique properties stem from its atomic structure, particularly the sp2 hybridized covalent bonding of its carbon atoms, its free Pi electron availability and nanoscale thickness of 0.345 nm.  As a reference, 3 million layers of graphene would be only slightly thicker than 1 mm. Graphene stacked >10 layers is technically classified as graphite. Graphene is the thinnest material known to man – so thin, in fact, that it has only two dimensions. With a density of 0.77 mg/m², it also has the highest known surface area any material.

The properties of exfoliated graphenes such as GO and rGO can vary significantly depending on the quality of the mined graphite raw material and exfoliation process used. In contrast, graphene manufactured using CVD, is largely dependent upon highly controlled and predictable industrial material inputs, including the substrate metal foils and the carbon gas precursor. Graphene recipes are designed by varying the pressures and mixtures of the gases used and because a more controllable process is utilized, the quality is generally more consistent.

While a number of factors influence graphene nucleation and growth, it is well established that CVD graphene will always have edges, nanoscale defects and grain boundaries where carbon to carbon bonding can be disrupted. The basic process for CVD graphene production on Copper and Ni is described in the diagram below.

General Graphene Corporation, a leading large-scale graphene manufacturer, producer and supplier has developed a series of proprietary, customized production equipment for its CVD graphene. Our systems are programmable, fully automated and operate in a continuous roll-to-roll format at atmospheric pressure. This allows us to produce consistent quality graphene that can be tailored to meet the needs of specific applications.

But when it comes to graphene, we believe that “good” is a relative measure – what may be “good” for one application may not perform for another. Thus, we eschew labels such as “good” because what ultimately matters most is whether the graphene performs. Graphene is not a “one size fits all material” and must be designed to consistently meet the performance needs of industry and the user.

Among the properties/characteristics with respect to which we can optimize our graphene to meet the needs of the application are:

For a more detailed analysis, see our graphene specification section.

CVD Graphene is an incredibly versatile material and has unlimited applications. No other material offers its combination of properties. Thus, while the list of applications is effectively limitless, the following represent applications which have attracted significant attention.

• Electronics:
  • Transparent conductors (touch screens)
  • Optoelectronics (IR detectors)
  • Sensors
• Energy Production & Storage:
  • Batteries
  • Supercapacitors
  • Fuel cells
  • Solar panels
• Life Sciences and Bio Engineering:
  • Medical devices
  • In vitro coatings for biocompatibility
  • Growth mediums for cell biology/microbiology
  • Biofilm inhibitors for medical and industrial applications
  • Biosensors
  • Drug coatings
• Filtration and Membranes:
  • Water and wastewater cleanup
  • Desalination
  • Biopharma and consumer industries
• Composites:
  • Automotive
  • Aerospace
  • Construction

More than 40,000 world-wide graphene-related patent applications have been filed which employ graphene to enhance existing and new products in virtually every industry sector.  The chart below provides a broad overview of graphene’s versatility.

How many layers of graphene do you need?

We make single layer graphene, multi single layer graphene (defined as several single layer graphene sheets placed on top of each other), multilayer graphene (multiple layers grown at the same time) and multi-multilayer graphene (defined as several multilayer graphene sheets placed on top of each other). Currently the width of a single sheet is limited to 300mm, but its length can be whatever you need.

Is graphene expensive?

Purchasing graphene has been difficult and incredibly expensive. However, because cost is arguably the biggest impediment to the commercialization of graphene, General Graphene’s manufacturing and graphene transfer systems were specifically designed to produce industrial scale, low-cost and consistent graphene.

At General Graphene, the graphene cost will generally be a function of the affordability of graphene in the application for which it is intended. In this way, the industry can precisely calculate the economic benefit of implementing a graphene solution.

General Graphene is the only graphene company in the world that can manufacture large quantities of graphene. That’s because we use our patented and proprietary atmospheric CVD process which – for the first time ever – produces high volume, roll-to-roll graphene films making graphene available in large quantities and can be used across multiple industries.

The breakthrough in the manufacture of industrial quantities of CVD graphene was the development of our atmospheric, roll-to-roll production system, which offers world class production levels at an affordable cost across industries. Our industrial manufacturing cells are scalable at relatively low cost, enabling the possibility to create large scale graphene manufacturing units, close to downstream OEM’s.

Only General Graphene can produce graphene continuously, so the length limit is defined only by the customer’s production and handling requirements. That means, graphene film dimensions produced here are only limited by width. We can provide continuous graphene up to 400mm wide, but generally, we produce graphene to 300mm wide to fit the width of the substrate.

Graphene is very strong – but only at the atomic scale. For example, the average human hair has a diameter is approximately 100 µm, 100,000 times thicker than a single layer of graphene and is extremely fragile. For this reason, when graphene is removed from the growth substrate, we always use a polymer support layer (e.g., PMMA, polystyrene, polyethylene, Kapton, Mylar, lacquer, etc…

There are multiple ways to transfer graphene from the growth substrate to its target substrate. The ideal removal method is dependent upon the application for which the graphene is intended. We have patented several removal techniques and use several others. Our removal and transfer methods generally center on wet and dry removal processes, and focus on industrial scale manufacturing needs at the OEM.

How we apply the graphene depends on what we are applying it to and the needs of the application. At industrial scale, transfer can be tricky. We encourage all of our customers to work closely with our scientists and industrial engineers to design the removal and transfer processes and ensure that the graphene performs as required on the target substrate.

If you are looking to acquire graphene for product development, it is best is first to contact General Graphene to discuss your individual need.

Typically, we like to discuss the project before providing samples. We want to do all we can to ensure that industries new to graphene, have a positive experience and develop new systems efficiently and at low development cost. The application development process is often new and demanding and requires a level of knowledge and experience exchange to get the product right. Therefore, our preferred business model is to engage in development agreements to maximize the efficiency of a new product development program.

Our first graphene sheet came off our development equipment in 2016. Since then, we have continued to develop the process and equipment package. Our latest production machine will produce up to 200 square meters of graphene per day.

Our next generation production machine is in the design phase and is scheduled to be commissioned in Q4 2021. Its production capacity is anticipated to be 1,000-2,200 square meters per day. Our equipment is designed to be scalable at low cost to meet the quantities demanded by industry.

Sixteen years of intensive scientific research have proven graphene to be an incredible material. However, taking graphene from the lab to industrial scale has faced significant challenges; mainly producing consistent quality graphene sheets at scale and an affordable price.

General Graphene was founded on the premise that, in order to industrialize graphene’s amazing properties, we would have to focus on engineering at scale.

We are addressing these issues by designing state-of-the-art production system that can produce in excess of 100,000 square meters/year, at significantly lower manufacturing costs. Furthermore, our systems are designed to scale and produce the consistent volumes that industry needs. Higher-speed manufacturing units are already in design for commissioning end of 2021.

It is perfectly safe to handle CVD graphene and there are no known health or safety issues associated with film-based graphene. Numerous carbon medical products have been approved by the FDA since the late 1960s, and the biocompatibility of graphene is well documented. Indeed, CVD graphene is a highly prized growth substrate for human stem cells.