Unique Nanostructures of Carbon Nano Onions

Carbon nano onions (CNOs), concentric multi-graphitic layered fullerenes, have gained significant attention due to their exceptional physiochemical properties and versatile characteristics, leading to their widespread popularity in various fields. This comprehensive chapter explores different synthesis methods for CNOs, emphasizing thermal annealing as the most efficient approach. It discusses the purification techniques to address impurities, characterizes CNOs through various instrumental techniques to uncover their unique properties, and explores doped and composite CNOs with high chemical reactivity. The chapter also addresses the non-toxic nature and excellent biocompatibility of CNOs, showcasing their applications in biology and medicine. It concludes by highlighting the current and future applications of CNOs in areas such as superconductors, biosensors, drug delivery, batteries, and tissue engineering, highlighting their increasing popularity and vast untapped potential.