Carbon Dots for Lubrication Applications: A Review

Friction is a major contributor to global energy loss and component degradation, resulting in significant economic costs worldwide. To address this challenge, considerable research has focused on the development of advanced friction-reducing materials. Among these materials, carbon dots (CDs) have recently emerged as highly promising lubricant additives, owing to their tunable surface chemistry, excellent dispersion stability, cost-effective synthesis, and environmental friendliness. Despite notable progress, a comprehensive and critical assessment of recent developments in CD-based lubrication is still lacking. This review addresses this gap by summarizing recent advances from three perspectives. First, strategies for enhancing the tribological performance of CDs are discussed, including surface modification, heteroatom doping, and emerging solvent-free and liquid-like CDs. Second, the expanding application of CDs in diverse lubrication systems, ranging from liquid lubrication to solid–liquid composite lubrication and solid lubrication, is reviewed. Third, the lubrication mechanisms of CDs as additives are examined. Finally, key challenges and future prospects are discussed to guide the further development of CDs in lubrication.