Correlated morphological and chemical mechanisms for the superior corrosion resistance of alumina-deposited 2D nanofilms on copper

Abstract As promising anticorrosion coatings with excellent impermeability to most atoms and molecules, the performance of graphene (Gr) and hexagonal boron nitride (BN) are still limited by the inevitable defects and grain boundaries within these two dimensional films (2DFs) grown on metal substrate by chemical vapor deposition. In this work, we use the atomic layer deposition (ALD) with Al2O3 to passivate defective graphene and BN grown on Cu, and controllably realize superior corrosion resistance on Al2O3/Gr/Cu and Al2O3/BN/Cu systems in both short-term corrosion tests (10 hours, 3.5 wt% NaCl solution) and long-term exposure to humid air (up to 18 months). By comprehensively using various experimental characterization methods, combined with density-functional-theory calculations, we reveal the correlated morphological and chemical mechanisms for the enhanced corrosion resistance by Al2O3 deposition for both Gr/Cu and BN/Cu substrates, as well as the difference between them: (1) Al2O3 grows uniformly on BN/Cu but selectively on the defective sites of Gr/Cu, due to the stronger Al2O3—BN/Cu interface bonding; (2) The Al2O3—2DF/Cu interfaces have a high blocking effect on the transport of H2O molecule, explaining the enhanced anticorrosion by the Al2O3 deposition; (3) The transport of H2O molecule in the Al2O3—BN/Cu interface is much slower than that in the Al2O3—Gr/Cu interface, explaining the more remarkable effect of Al2O3 deposition on BN/Cu substrate. This work offers a meaningful instruction for accurate interface design of 2DFs towards the ultrahigh anticorrosion applications.