In 2004, two physicists at the University of Manchester peeled a layer of carbon from a block of graphite using ordinary adhesive tape — and launched a materials revolution. That single sheet of carbon atoms, just 0.34 nanometers thick, turned out to be the strongest material ever measured, one of the best electrical and thermal conductors known, and nearly transparent. Two decades later, graphene is moving from laboratory curiosity to commercial reality. But separating genuine science from marketing hype requires understanding what graphene actually is, what forms it takes, and why quality makes all the difference.
What Is Graphene?
At its simplest, graphene is a single layer of carbon atoms arranged in a flat, two-dimensional hexagonal lattice — picture a sheet of chicken wire scaled down to atomic dimensions. Every carbon atom in the lattice forms three bonds with its neighbors through a process called sp² hybridization, which creates the rigid honeycomb structure and leaves one electron per atom free to move across the entire sheet.
That free electron system is what makes graphene extraordinary. The electrons in graphene don’t behave like electrons in ordinary metals. Instead, they act as what physicists call Dirac fermions — effectively massless charge carriers that travel at a constant speed of roughly 1/300th the speed of light, regardless of their energy. In practical terms, this means electrons encounter remarkably little resistance as they move through graphene, giving the material its extreme electrical conductivity.
This isn’t just a theoretical curiosity. The combination of sp² bonding (which makes the lattice mechanically rigid and chemically stable) and the Dirac fermion behavior (which enables extraordinary electrical properties) is what sets graphene apart from every other material. No other substance packs this combination of strength, conductivity, transparency, and flexibility into a single atomic layer.
Key Properties and Why They Matter Commercially
Graphene’s properties are not merely impressive in isolation — they are extraordinary in combination. Here is what the measured numbers actually mean for real-world applications.
Mechanical Strength
Graphene has an intrinsic breaking strength of approximately 42 N/m (equivalent to ~130 GPa tensile strength when normalized by thickness). To put that in perspective, this makes graphene over 100 times stronger than the strongest steel when compared by weight. Despite this strength, graphene is not brittle — it can sustain elastic deformation of up to 25% before failure. For composite manufacturers, even small additions of graphene to polymers, metals, or ceramics can dramatically improve tensile strength and stiffness without significant weight penalties.
Optical Transparency
A single graphene layer absorbs exactly 2.3% of visible light — a number that, remarkably, is defined entirely by fundamental physical constants (specifically, πα, where α is the fine-structure constant). This near-total transparency, combined with high electrical conductivity, makes graphene a candidate to replace indium tin oxide (ITO) in touchscreens, OLED displays, and solar cells. Unlike ITO, graphene is flexible and does not crack when bent, which matters enormously for foldable and wearable electronics.
Electrical Conductivity
Graphene’s electron mobility can exceed 200,000 cm²/V·s in suspended, pristine samples at room temperature — roughly 100 times higher than silicon. In practice, the conductivity of commercially produced graphene is highly quality-dependent. CVD-grown monolayer graphene on a substrate typically achieves sheet resistance values of 125–500 Ω/sq, which is competitive with ITO. However, graphene nanoplatelets and reduced graphene oxide exhibit far lower conductivities because of defects and inter-flake resistance. This quality dependence is one of the most important — and most frequently overlooked — facts about graphene.
Thermal Conductivity
Graphene’s thermal conductivity reaches approximately 5,000 W/m·K in suspended monolayer form, exceeding that of diamond (~2,200 W/m·K) and making it the best thermal conductor ever measured. For electronics manufacturers dealing with increasingly dense chip packaging, graphene-based thermal interface materials and heat spreaders offer a path to managing thermal loads that conventional materials cannot handle.
The Different Types of Graphene
This is where the graphene industry gets confusing — and where many buyers get misled. “Graphene” is not one product. The term covers a family of related materials with vastly different properties, production methods, and price points. Understanding these distinctions is essential for anyone evaluating graphene for commercial use.
| Material | Layers | Typical Production | Key Properties | Common Applications |
|---|---|---|---|---|
| Monolayer graphene | 1 | CVD on copper, mechanical exfoliation | Highest conductivity, transparent, flexible | Transparent conductors, sensors, electronics |
| Bilayer graphene | 2 | CVD, exfoliation | Tunable bandgap under electric field | Transistors, photonics |
| Few-layer graphene (FLG) | 2–10 | Liquid-phase exfoliation, milling | Good balance of properties and scalability | Composites, inks, coatings |
| Graphene nanoplatelets (GNP) | ~10–30+ | Exfoliation of graphite | High surface area, good filler properties | Polymer composites, lubricants, batteries |
| Graphene oxide (GO) | 1 (oxidized) | Hummers method | Water-dispersible, chemically functionalizable | Membranes, biomedical, coatings |
| Reduced graphene oxide (rGO) | 1 (partially restored) | Chemical/thermal reduction of GO | Partially restored conductivity | Energy storage, conductive inks |
The critical point: a company selling “graphene powder” at $50/kg is almost certainly selling graphite nanoplatelets or low-quality FLG — not monolayer graphene. Monolayer CVD graphene on copper foil costs orders of magnitude more and is sold by the square centimeter, not by weight. These are fundamentally different materials with fundamentally different performance characteristics, and conflating them leads to failed applications and wasted development budgets.
Why Layer Count and Quality Matter
The graphene industry has a well-documented mislabeling problem. A 2018 study published in Advanced Materials tested graphene samples from 60 suppliers worldwide and found that fewer than 10% of products labeled as “graphene” actually contained more than 10% monolayer content. Most were multilayer graphite with marginal property improvements over conventional carbon additives.
This matters commercially because graphene’s exceptional properties degrade rapidly with increasing layer count. By the time you reach 10+ layers, you are essentially working with thin graphite — a useful material, but not one that justifies a premium price or warrants the “graphene” label.
Layer count affects performance in measurable ways:
- Electrical conductivity — Monolayer graphene has the highest intrinsic mobility. Each additional layer reduces the proportion of surface-area electrons available for conduction, and inter-layer scattering introduces resistance.
- Transparency — Each added layer absorbs another 2.3% of light. By 10 layers, you have lost nearly a quarter of the transmitted light.
- Mechanical reinforcement — In composites, the surface-area-to-volume ratio is what drives performance. Thinner flakes with higher aspect ratios provide dramatically better reinforcement per unit weight.
- Surface chemistry — GO and rGO applications depend on functional groups on the basal plane, which are only accessible on exposed surfaces.
The ISO/TS 80004-13 standard defines graphene as a single layer, and few-layer graphene as 2–10 layers. If a supplier cannot tell you the layer-count distribution of their product — measured, not claimed — that is a significant red flag.
How Graphene Quality Is Measured
The primary tool for characterizing graphene is Raman spectroscopy, which uses a laser to probe the vibrational modes of the carbon lattice. A Raman spectrum of graphene produces three signature peaks that reveal nearly everything a buyer needs to know:
- G peak (~1,580 cm⁻¹) — Present in all graphitic carbon. Confirms you have sp²-bonded carbon material.
- 2D peak (~2,700 cm⁻¹) — The shape, position, and intensity of this peak relative to the G peak indicate layer count. A sharp, symmetric 2D peak with intensity roughly twice the G peak is the fingerprint of monolayer graphene. As layers increase, the 2D peak broadens, shifts, and weakens relative to G.
- D peak (~1,350 cm⁻¹) — The “defect” peak. Its presence indicates broken bonds, edges, or lattice imperfections. A high D/G intensity ratio signals poor-quality material with significant structural damage.
When evaluating a graphene supplier, ask for Raman spectra — not marketing data sheets. Specifically, look at the 2D/G ratio (should be ≥2 for monolayer), the D/G ratio (should be <0.1 for high-quality material), and the 2D peak shape (should be a single, symmetric Lorentzian for monolayer). These three measurements are more informative than any claimed specification.
A Brief History
Theorists predicted the properties of isolated graphene layers decades before anyone produced one. The carbon honeycomb lattice was well understood, but a 1935 argument by Peierls and Landau suggested that strictly two-dimensional crystals should be thermodynamically unstable — they would buckle, scroll, or decompose rather than exist as flat sheets.
That conventional wisdom held until 2004, when Andre Geim and Konstantin Novoselov at the University of Manchester demonstrated a disarmingly simple technique: pressing adhesive tape onto a graphite crystal, peeling it away, and repeating the process until only a single atomic layer remained on a silicon substrate. This mechanical exfoliation method — sometimes called the “scotch tape method” — produced the first confirmed samples of isolated monolayer graphene.
Their measurements confirmed the theoretical predictions. The material was stable at room temperature, exhibited the predicted Dirac fermion behavior, and displayed extraordinary mechanical and electronic properties. Geim and Novoselov were awarded the 2010 Nobel Prize in Physics “for groundbreaking experiments regarding the two-dimensional material graphene.”
Since 2004, global investment in graphene research has exceeded $20 billion. Over 300,000 papers have been published, more than 100,000 patents filed, and hundreds of companies now produce some form of graphene material. The challenge today is no longer proving that graphene works — it is producing it at the right quality, in the right form, at a commercially viable cost.
What Comes Next
Understanding what graphene is — and what it is not — is the foundation for everything that follows. The next critical question is how graphene is produced at scale, and why the choice of production method determines the material’s properties, quality, and commercial viability.
Read next: How Graphene Is Made: Manufacturing Methods Compared to understand CVD, liquid-phase exfoliation, and the trade-offs every manufacturer navigates between quality, scale, and cost.
This article is part of the Fundamentals series on Graphene Guide. For definitions of technical terms used in this article, see the Graphene Glossary.