Two-dimensional iron oxide/graphene-based nanocomposites as high-performance solid lubricants

Abstract Beyond conventional 2D layered materials such as graphene and transition metal dichalcogenides, 2D metal oxides have also received much interest in recent years. They have unique electronic (such as 2D TiO₂ and MoO₂), catalytic (such as 2D CeO₂ and MnO₂), and magnetic properties (such as 2D Fe₂O₃) compared with bulk metal oxides due to their atomically thin structures. Certain types of 2D metal oxides also have the potential to be a new type of high-performance solid lubricants due to the tunable interlayer interaction and possibility for 2D heterostructure formation, but this remains largely unexplored. In this work, we developed a scalable microwave-assisted solid-state synthesis of 2D Fe₂O₃ and their nanocomposites with reduced graphene oxide (rGO). The 2D Fe₂O₃/rGO nanocomposites were systematically characterized by electron microscopies and spectroscopies, and their utilization as solid lubricants was studied by pin-on-disk tribometer on both silicon and steel substrates. The results show that due to the easy sliding between 2D Fe₂O₃ and rGO nanosheets and their unique magnetic-induced assembled morphology, low coefficient of friction (COF) can be achieved for both steel-silicon and steel-steel interfaces. Superlubricity (COF ∼ 0.007) can be achieved for the 2D Fe₂O₃/rGO nanocomposite with a GO primer layer on a steel substrate. This work provides new insights into the development of functional 2D nanocomposites and expands their applications to solid lubrication and beyond.