Atomic-scale reconstruction of sapphire induced by selective tribochemical removal of surface atoms

Although biomimetic nanostructured surfaces can impart exceptional properties, their inherent fragility makes them prone to failure under mechanical wear. This study presents a method for friction-induced atomic-scale surface reconstruction of sapphire, resulting in durable, scale-like nanostructures that retain the hardness of bulk the sapphire (27.2 GPa). Friction experiments and reactive force field molecular dynamics simulation reveal that surface reconstruction is driven by the selective removal of atoms from less chemically inert crystal planes of sapphire via interfacial bridge bonds during friction with SiO₂. Subsurface characterizations demonstrate that the nanostructures maintain a consistent single-crystal structure with the original sapphire, thereby ensuring their exceptional mechanical properties. To evaluate its triboelectric performance and wear resistance, nanostructured sapphire is integrated into triboelectric nanogenerators (TENGs) with a diamond-like carbon (DLC) friction layer. Triboelectric tests indicate that after 100k cycles of friction, the discharge performance of TENGs exhibits no significant decline, and the nanostructures show negligible wear, demonstrating their extraordinary durability. This study introduces an atomic-scale strategy for nanostructure fabrication, providing an approach to surface reconstruction of sapphire and insights into the development of wear-resistant nanostructures.