What are the fullerenes primarily made of?

Fullerenes are a class of carbon allotropes that are primarily composed of carbon atoms. They are unique in their molecular structure, typically forming hollow spheres, ellipsoids, or tubes. The most famous fullerene is C60, which is shaped like a soccer ball, comprising 60 carbon atoms arranged in a pattern of pentagons and hexagons. This specific arrangement of carbon atoms gives fullerenes their remarkable properties, such as strength, conductivity, and unique reactivity.

Understanding that fullerenes are entirely carbon-based is key to their classification and the study of nanoscale materials. This also distinguishes them sharply from other materials like silicon, which is a semiconductor, ionic compounds, which consist of metal cations and non-metal anions, and metals themselves, which possess distinct properties such as malleability and conductivity based on their metallic bonding. The carbon-based nature of fullerenes not only leads to their unique chemical and physical properties but also plays a critical role in various applications, including drug delivery and materials science.