13 bonds due to the presence of oxygenated functionalities. 42,46 The π-π* peak red-shifted to 267 nm upon reduction to graphene with hydrazine and the absence of n-π* transitions at 310 nm indicates the removal of the oxygen functionality from GO after reduction by hydrazine. In GO-ODA, the π-π* transitions of graphitic C=C bonds shifted to 266 nm, and n-π* transitions of C-O bonds completely disappeared similar to graphene indicates the simultaneous formation of RGO and functionalization with ODA molecules. Fig 1: (a) FT-IR transmittance spectra of GO, GO-ODA, Graphene, (b) UV-Visible absorption spectra of GO and graphene in water and GO-ODA chloroform medium, (c) Raman spectra of GO, GO-ODA and graphene.Raman spectroscopy is a powerful nondestructive tool to distinguish order and disorder in the crystal structure of materials as Raman scattering is strongly dependent upon its electronic structure. The crystal structure of graphite is altered during the oxidation process of graphite to graphite oxide. However, the reduction process of GO to graphene and GO-ODA partially restored the ordered crystal structure and also repaired few of the structural defects in the

No abstract

The present study demonstrates an improved and facile method for the exfoliation and chemical oxidation of bulk hexagonal boron nitride (h-BN) powder. Further, chemical functionalization of oxidized h-BN with (3-aminopropyl) trimethoxysilane (APTMS) as a bifunctional chemical linker has been undertaken to prepare APTMS-grafted h-BN (h-BNAS). Amino-terminated functional groups on the basal plane defect and edge sites of h-BNAS were targeted for further chemical grafting with graphene oxide (GO) through covalent interaction to achieve an h-BN/GO nanocomposite (h-BNAS@GO). The chemical structure and morphology of h-BN, oxidized h-BN, h-BNAS, and h-BNAS@GO were investigated through standard spectroscopic and microscopic analyses. The macro- and microtribological results depicted that the h-BNAS@GO hybrid composite (0.5 wt %) as an oil-dispersible additive significantly reduced the coefficient of friction (COF) and wear of the steel-steel tribopair, revealing superior tribological properties. The COF of h-BNAS@GO nanocomposite exhibited a reduction of 50.7% (at P m ≈ 1.95 GPa) than that of base paraffin oil and showed a lower specific wear rate (1 × 10–8 mm3/N-m) at macrotribological trials, revealing the best wear-resistance performance. At microtribological reciprocating sliding, the composite nanolubricant was observed to diminish the COF by ∼41.18% (at P m ≈ 2.15 GPa) compared to base oil. The post-tribological analysis of the worn tribotracks demonstrates that the h-BNAS@GO nanocomposite has a superior ability to adhere and form a thicker, continuous, synergetic lubricating tribofilm at the interfaces, thereby effectively reducing COF and protecting the tribopairs from wear. Therefore, the h-BNAS@GO nanocomposite has a great prospect as a load-bearing lubricating advanced material in convenient industrial application.