Anticorrosive two-dimensional heterostructured nanocoatings self-assembled on steel with multiple desired merits

In this study, an economic and controllable Marangoni self-assembly approach is designed to prepare the heterostructured nanocoatings (8-28 nm) consisting of alternately stacked mosaic nanosheets of hexagonal boron nitride (h-BN) and graphene. The resulting 2D nanocoatings exhibit a combination of advantageous properties, such as prevention of interfacial reactions, robust interfacial binding, a labyrinthine barrier effect, inhibition of galvanic corrosion, and alleviation of internal stress. The protective property of graphene/h-BN heterostructured nanocoatings is studied through potentiodynamic polarization curves and electrochemical impedance spectroscopy, with the theoretical support of first-principles calculations. The corrosion current density of ≈28 nm-thick graphene/h-BN multilayer coated stainless steel is 1.82 × 10^-8 A cm^-2, which decreases by an order of magnitude compared to that of an uncoated one, meanwhile, the corrosion potential increases from -0.192 to 0.023 V (increase: ≈0.215 V). The enhancement of anticorrosion performance of heterostructured nanocoatings can be attributed to the labyrinth barrier effect associated with highly ordered horizontal arrangement, effective coverage of metal substrates by mosaic multilayers, and suppressed galvanic corrosion effect by insulating BNNS monolayers. This study can shed much light on the effective solution of many stubborn issues confronted by the development of anticorrosive 2D nanocoatings.