Constructing g-C3N4 nanosheets/deep eutectic solvent nanofluids as high-performance additives for polyethylene glycol

Abstract

Owing to their exceptional thermal stability, distinctive internal layered structure, and superior mechanical strength, graphitic carbon nitride (g-C₃N₄) materials hold great potential as additives for base oils in the field of lubrication. However, their incompatibility with various base oils has significantly impeded their practical application. In this study, homogeneous and optically transparent g-C₃N₄ nanosheet/deep eutectic solvent (DES) nanofluids were successfully constructed through hydrogen bond interactions. When incorporated as additives into polyethylene glycol, these nanofluids demonstrated exceptional dispersion stability along with outstanding tribological properties, including remarkable friction reduction, excellent anti-wear performance, superior load-carrying capacity, and prolonged service lifespan. The synergistic effects of tribo-chemical reactions between the DES and iron surface interface and the interlayer sliding and self-repairing properties of g-C₃N₄ nanosheets played pivotal roles in forming a robust boundary lubrication film. This tribo-induced film, comprising g-C₃N₄ nanosheets and tribo-chemical derivatives (including iron oxides and iron nitride), exhibited remarkable tribological enhancement, effectively reducing friction and wear of the friction pair. These findings are expected to provide valuable insights into the practical application of g-C₃N₄ materials in the development of advanced lubricant additives.