Black phosphorus nanosheet dotted with Fe3O4-PDA nanoparticles: A novel lubricant additive for tribological applications

Abstract

The enhancement of black phosphorus applications and its lubricating properties as an additive are subjects of growing interest. Here, a novel BP/Fe₃O₄-PDA nanocomposite was synthesized by a facile approach. The results suggested that black phosphorus was successfully dotted with spherical Fe₃O₄ and PDA nanoparticles, which induced an amorphous alteration in black phosphorus. The obtained nanocomposites exhibited excellent dispersion stability in soybean oil compared to pure black phosphorus. The tribological performance of BP/Fe₃O₄-PDA nanocomposites in soybean oil and grease was evaluated by a ball-on-disc tribometer under high load. It was found that the use of BP/Fe₃O₄-PDA additives greatly reduced the friction coefficient (by 55.3 % in oil, 64.3 % in grease) and wear, proving to be more effective than BP additives. The findings revealed that the tribofilm comprising Fe₃O₄, PDA, and black phosphorus were generated at the friction interface, and their synergistic lubrication was deemed the primary factor enhancing the lubricating properties of oil and grease by BP/Fe₃O₄-PDA nano-additives. Additionally, the carbon film extracted from soybean oil was regarded as a contributing factor to the superior lubricating properties of BP/Fe₃O₄-PDA when used as additives in oil. This work paves the way for broadening the tribological applications of black phosphorus in lubricating oils and greases.