Chemically functionalized 2D/2D hexagonal boron Nitride/Molybdenum disulfide heterostructure for enhancement of lubrication properties

Abstract

Ultralow friction arising from interfaces of incommensurately stacked 2D/2D heterostructure of two different crystal lattices provides a promising solution for designing a new generation lubricants of superior tribological properties. Present work addressed the chemically functionalized 2D/2D heterostructure of h-BN and MoS2 nanosheets as a dispersible additive to engine oil for reducing friction and material losses. The h-BN nanosheets prepared by alkali-assisted hydrothermal exfoliation are used for growing the MoS2 lamellae via a chemical reduction in the presence of cetyltrimethylammonium bromide (CTAB). The XPS, FTIR, Raman, XRD, and HRTEM analyses confirmed the synthesis of the h-BN-MoS2-CTAB heterostructure. The grafting of CTA furnished excellent dispersibility of h-BN-MoS2-CTAB heterostructure in fully formulated engine oil, which ensured their uninterrupted supply to contact interfaces of steel tribopair. A minute dose of h-BN-MoS2-CTAB (30 ppm) to engine oil decreased the friction and wear by 44% and 96% for steel tribopair. The improved lubrication properties are ascribed to the excellent dispersibility of h-BN-MoS2-CTAB heterostructure in engine oil, low shear strength of incommensurately stacked h-BN and MoS2 lamellae, and the formation of protective thin film on steel tribo-interfaces. These findings suggest that 2D/2D heterostructure can be revolutionary materials for developing new generation lubricants.