Heterolamellar Bi₂Se₃/Bi₂WO₆ and Bi₂Se₃/N-Doped Bi₂WO₆ Nanosheet Composites as Potential Antifriction and Antiwear Agents

Abstract

Hydrothermally synthesized bismuth selenide (Bi2Se3) nanosheets were reinforced by introducing lamellar bismuth tungstate (Bi2WO6) to obtain a heterolamellar structure anticipating higher tribological efficiency. For the furtherance of efficiency, the bismuth tungstate was nitrogen-doped (N-Bi2WO6) and was used to reinforce Bi2Se3 nanosheets. The propensity toward two-dimensional (2D) materials for the fabrication of composites was based on the presence of weak van der Waals forces between the adjacent layers, which eventually promotes lubricious behavior together with enhanced dispersibility. Examination of the hybrid nanosheets Bi2Se3/Bi2WO6 and Bi2Se3/N-Bi2WO6 by high-resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), and high-resolution TEM (HR-TEM) demonstrated that Bi2WO6 and N-Bi2WO6 nanosheets were distributed uniformly onto Bi2Se3 nanosheets. The tribological attributes of well-identified nanoadditives Bi2Se3, Bi2WO6, N-Bi2WO6, Bi2Se3/Bi2WO6, and Bi2Se3/N-Bi2WO6 were evaluated in paraffin oil (PO) on a four-ball tester at an optimized concentration of 0.050% w/v operating ASTM D4172 and ASTM D5183 tests. The tribological data, mean wear scar diameter (MWD), friction coefficient (COF), and seizure load divulged that N-Bi2WO6 nanosheets behaved significantly better than Bi2WO6 nanosheets, which, in turn, surpassed the Bi2Se3 nanosheets. However, substantial upgradation of tribological activity was noted for the hybrid Bi2Se3/Bi2WO6 due to a heterolamellar structure with reduced interlaminar shear strength that effectively prevents restacking and agglomeration of nanosheets. For the advancement of tribological activity, the hybrid Bi2Se3/N-Bi2WO6 was prepared, which performed more efficiently than Bi2Se3/Bi2WO6. According to energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analyses of the worn pathway, the generated tribo-film comprised metal oxides, Bi2O3, SeO2, WO3, and tungsten nitride, which synergetically improved the lubricity. The wear scar surface analysis by atomic force microscopy (AFM) and SEM validated the observed tribological results.

Superlubricity of Nanocomposites of Polyaniline-Functionalized Reduced Graphene Oxide with Yttrium and Vanadium-Codoped Zinc Oxide Nanoparticles

“…Nanoparticles of metals such as Ni, Cu, , Ag, , and Pd and metal salts such as oxides ZrO 2, , ZnO, , and CeO 2; sulfides MoS 2, , WS 2, Ag 2 S, and CuS; selenides VSe 2 and Bi 2 Se 3 ; and halides like LaF 3 have been extensively investigated as components of nanolubricants. , Their composites with graphene, such as copper, silver, , Mn 3 O 4, ceria, zirconia, boron nitride, and WS 2 , are well documented in the literature for enhanced tribological performance. Some graphene-based nanocomposites were also investigated by performing superlubricity (COF less than 0.01). , A titanium dioxide-reinforced boron nitrogen-codoped graphene nanocomposite was reported from our laboratory for excellent tribological activity .…”