GRAPHENE

Name: Graphene (derived from “graphite,” from the Greek graphein, “to write”)

Symbol: C

Group: 14

Period: 2

Block: p

Category: Nonmetal (two-dimensional allotrope of carbon)

Atomic number: 6

Atomic mass: 12.011 u

Electrons per layer: 2.4

Electronegativity: 2.55

Density: ~0.77 mg/cm² (for a monolayer, equivalent to ~2.2 g/cm³ in theoretical volume)

Melting point: Not defined (decomposes before melting, ~3,650 °C in an inert atmosphere, similar to graphite)

Boiling point: Not applicable (sublimes at high temperatures)

Thermal conductivity: ~4,000–5,300 W/(m·K) (one of the highest) (known)

Electrical conductivity: ~10⁸ S/m (comparable to copper)

Magnetic order: Diamagnetic

Ordinary state: Solid (two-dimensional macromolecule)

Oxidation states: 0 (mainly), +2, +4 (in derived compounds)

Mohs hardness: Not applicable (two-dimensional material, mechanical strength ~1,300 GPa)

Vickers hardness: Non-standard (monolayer material)

Brinell hardness: Non-standard (two-dimensional material)

Most stable isotopes: C-12 (98.93%), C-13 (1.07%)

Discoverer: Andre Geim and Konstantin Novoselov (isolated in 2004, University of Manchester, UK; Nobel Prize in Physics 2010)

Graphene, a two-dimensional allotrope of carbon (C) composed of a monolayer of atoms arranged in a hexagonal lattice, is one of the most revolutionary materials in modern science, known for its mechanical strength (1,300 GPa), electrical conductivity (10⁸ S/m), and thermal conductivity (~4,000–5,300 W/m K). Although naturally occurring in graphite, where graphene layers are stacked and bonded by van der Waals forces, its isolation as an independent material marked a milestone in materials science. The history of graphene combines centuries of knowledge about carbon with recent advances in nanotechnology, culminating in a discovery that earned it the Nobel Prize in Physics in 2010. With a carbon abundance of ~200 ppm in the Earth's crust, graphene is not a rare raw material, but its isolation and controlled production have been remarkable scientific achievements. The concept of graphene dates back to theoretical studies of the structure of graphite, known since ancient times for its use in writing and lubrication. In 1859, British chemist Benjamin Brodie described the laminar structure of graphite, suggesting the existence of atomic layers of carbon, although he was unable to isolate them. During the 20th century, theorists such as Philip R. Wallace (1947) analyzed the electronic properties of a monolayer of graphite, predicting its semi-metallic behavior and high conductivity, laying the foundation for the study of graphene. However, it was believed that a pure two-dimensional material could not exist under stable conditions due to thermal instabilities, which delayed its experimental isolation.

The decisive breakthrough occurred in 2004, when physicists Andre Geim and Konstantin Novoselov, at the University of Manchester, isolated graphene using a surprisingly simple method: mechanical exfoliation with adhesive tape. By repeatedly peeling off layers of graphite, they were able to obtain stable monolayers and study their properties, publishing their findings in Science (2004). This discovery, which defied theoretical expectations, demonstrated that graphene was not only stable, but also exceptionally strong, flexible, and conductive, with 97.7% transparency to visible light. Their work earned them the Nobel Prize in Physics in 2010, marking the beginning of a global race to explore the applications of graphene. The exfoliation technique, although effective for research, was limited for large-scale production, leading to the development of methods such as chemical vapor deposition (CVD) in the 2000s, which allows graphene to be fabricated on substrates such as copper (Cu) for industrial applications.

Graphene has transformed multiple fields since its discovery. In electronics, it is used in transistors, flexible displays, and ultra-sensitive sensors, taking advantage of its high electron mobility. In energy, it improves the efficiency of lithium-ion (Li-ion) batteries, supercapacitors, and solar cells. In composite materials, it reinforces polymers and metals, creating lightweight structures for the aerospace and automotive industries. In biomedicine, its biocompatibility enables applications in biosensors and drug delivery systems. Global graphene production remains limited (~1,000 tons per year, estimated in 2025) due to the costs of synthesis processes, but its impact is immense, with a projected market of ~USD 1.5 billion by 2027. The history of graphene, from theoretical observations in the 19th century to its isolation in the 21st century, illustrates how a seemingly simple material has redefined the boundaries of science and technology, establishing itself as a pillar of modern innovation.

Graphene, a two-dimensional allotrope of carbon (C), is a monolayer of carbon atoms arranged in an sp² hybridized hexagonal lattice, with an atomic thickness of ~0.34 nm. Extracted from graphite, where the graphene layers are bonded by van der Waals forces, this semi-metallic material is renowned for its exceptional properties, making it a cornerstone of modern nanotechnology. With a carbon abundance of ~200 ppm in the Earth's crust, graphene is not uncommon as a raw material, but its isolation and large-scale production, using methods such as mechanical exfoliation or chemical vapor deposition (CVD), are technically challenging and expensive, driving its value in industrial and scientific applications. Physically, graphene stands out for its mechanical strength (1,300 GPa, 200 times greater than steel), making it one of the strongest materials known, despite its lightness (area density of ~0.77 mg/cm², equivalent to ~2.2 g/cm³ in theoretical volume). It is extremely flexible and transparent, absorbing only 2.3% of visible light, making it ideal for displays and optical sensors. Its electrical conductivity (10⁸ S/m) is comparable to that of copper (Cu), thanks to its high electron mobility, while its thermal conductivity (~4,000–5,300 W/(m K)) exceeds that of diamond, being one of the highest among solids. These properties, combined with its diamagnetic nature, enable applications in high-speed electronics and heat dissipation. 

Chemically, graphene is inert under standard conditions, resisting corrosion by oxygen (O₂), mild acids, and humid environments at room temperature. However, it can react with strong oxidizing agents or under high-temperature conditions (>500°C), forming graphene oxide. Its ability to be functionalized by the addition of chemical groups expands its use in biomedicine and composite materials. Graphene does not have a defined melting point, as it decomposes or sublimates at 3,650°C in inert atmospheres (such as argon). In applications, it is used in electronics (transistors, flexible displays), energy (lithium-ion batteries, Li-ion; supercapacitors), composite materials (polymer reinforcement), and biomedicine (biosensors, drug delivery). Although its production (estimated at 1,000 tons per year by 2025) is limited by costs, graphene redefines the limits of modern technology thanks to its unique combination of strength, conductivity, and versatility.

Graphene, a two-dimensional allotrope of carbon (C) composed of a monolayer of atoms in a hexagonal lattice (sp² hybridization), is a revolutionary material thanks to its mechanical strength (1,300 GPa, 200 times greater than steel), electrical conductivity (10⁸ S/m, comparable to copper, Cu), thermal conductivity (4,000–5,300 W/(m K)), and transparency (absorbing only 2.3% of visible light). With an atomic thickness of ~0.34 nm and a surface density of ~0.77 mg/cm², graphene combines lightness, flexibility, and chemical resistance, making it ideal for cutting-edge applications across multiple industries. Although its global production (an estimated 1,000 tons per year by 2025) is limited by the costs of methods such as mechanical exfoliation or chemical vapor deposition (CVD), its impact on modern technology is immense, ranging from electronics to biomedicine.

In electronics, graphene is a star material due to its high electron mobility and flexibility. It is used in high-speed transistors, flexible touchscreens, and ultrasensitive sensors, such as gas or radiation detectors, taking advantage of its conductivity and transparency. For example, graphene allows the development of flexible OLED displays for portable devices, outperforming traditional materials such as indium tin oxide (ITO). In energy, graphene improves the efficiency of lithium-ion (Li-ion) batteries, increasing capacity and charging speed when used in anodes or as a conductive additive. It is also used in supercapacitors, which offer rapid energy storage, and in solar cells, where its transparency and conductivity optimize light capture. Hydrogen (H₂) production benefits from graphene-based catalysts, which are more efficient and economical than platinum (Pt) catalysts.

In composite materials, graphene is incorporated into polymers, metals, and ceramics to create lighter and stronger materials used in the aerospace, automotive, and construction industries. For example, graphene-reinforced composites improve the impact resistance of aircraft or vehicle parts, reducing weight without sacrificing durability. In biomedicine, its biocompatibility and chemical functionalization capacity enable applications in biosensors to detect biomarkers (such as glucose or DNA), controlled drug release systems, and scaffolds for tissue engineering. In the environmental industry, graphene is used in membranes for water filtration and desalination, thanks to its low porosity and chemical resistance to agents such as chlorine (Cl₂) or mild acids. Although production costs (~$100–1,000/g for high-quality graphene) limit its mass adoption, graphene continues to transform key sectors, establishing itself as a material of the future with a projected market of ~$1.5 billion by 2027.