graphene

Graphene is a two-dimensional allotrope of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice. It is the basic structural element of many carbon-based materials, including graphite, charcoal, carbon nanotubes, and fullerenes. Graphene's atomically thin, planar form gives it unique physical properties that differ from those of bulk graphite.

In terms of strength and stiffness, graphene is exceptionally robust, with a reported Young's modulus around 1 terapascal and high intrinsic strength, while remaining light. It is an excellent conductor of electricity and heat, with high carrier mobility and thermal conductivity. It also absorbs very little light per layer, transmitting about 97.7% of visible light, making mono- or few-layer graphene nearly transparent.

Electronically, pristine graphene has no band gap and features a linear energy-momentum relation near the Dirac points, leading to behavior akin to massless Dirac fermions. These properties enable high-speed electronic devices and field-effect transistors; electrical characteristics can be tuned by chemical doping or electrostatic gating. Graphene can be produced by several methods, including mechanical exfoliation, chemical vapor deposition, and chemical reduction of graphene oxide.

Graphene's potential applications span flexible electronics, transparent conductive films, energy storage, composites, sensors, and membranes for gas separation or water purification. Realizing widespread commercial use faces challenges in scalable production, defect control, cost, and integration with existing manufacturing, as well as potential environmental and health considerations.