One-step rapid fabrication of high-purity onion-like carbons as efficient lubrication additives

Abstract

Onion-like carbons (OLCs), as a dazzling star of carbon nanomaterials, have been applied in various fields, such as lubrication, biomedicine, catalysis and energy storage. However, it is still a challenge to prepare OLCs using a solvent-free, time-saving and efficient strategy. Herein, the high-purity OLCs in high reproducibility without any post-treatment are prepared within 3–5 ms by a one-step gaseous detonation approach using untreated benzoic acid as the precursor, as well as acetylene (C2H2) and oxygen (O2) as explosion sources. The as-prepared OLCs with an average diameter of ca. 50.5 nm possess near-spherical and multi-layered concentric structure, which is highly beneficial for lubrication. Based on the characteristics of gaseous detonation and the morphology of OLCs, the formation mechanism of OLCs is speculated. Moreover, using a four-ball tester, the tribological properties of OLCs as lubricant additives for 150SN mineral oil are investigated. Strikingly, compared with those of neat 150SN mineral oil, the mean friction coefficient (f), wear scar diameter (d), wear scar depth (D) and wear rate (δ) of lower balls of OLCs/150SN suspensions with the concentration of 0.8 wt% under 392 N are reduced by 47.2%, 30.7%, 56.7% and 77.0%, respectively, indicating that OLCs can serve as excellent lubrication additives. This research not only provides a one-pot, rapid and facile gaseous detonation route to fabricate high-purity and high-reproducibility OLCs on a large scale, but also demonstrates the potential application of OLCs in lubrication.