Design of novel lubricating structured MOF-on-MOF heterostructure towards the tribological application

The merits of the elastic stiffness and flexible structure of 0D metal organic frameworks (0D MOFs) and the super-lubrication structure of 2D MOFs were conductive to improve the tribological performance of oil. In present paper, the spherical structure ZIF-7 nanoparticles and flake-like 2D Ni-BDC nanosheets were incorporated into the “ball-on-plate” heterostructure by in-situ synthesis route. The composition and structure of ZIF-7/2D Ni-BDC heterostructure were determined by a series of characterization technologies, which proved the spherical structure ZIF-7 nanoparticles grown on the surface of 2D Ni-BDC nanosheets. The ZIF-7/2D Ni-BDC heterostructure as additive in oil exhibited the better dispersibility and stability. The tribological experiments demonstrated that the ZIF-7/2D Ni-BDC heterostructure added into liquid paraffin effectively reduced by 39.7% in the friction coefficient and 18.03% in wear scar diameter at 0.08 wt% addition relative to pure liquid paraffin. The worn surface and debris characterizations confirmed that the “ball-on-plate” heterostructure could yield the synergistic effect of “rolling” and “interlayered sliding” in the friction process, thus significantly improving the lubrication performance of liquid paraffin.