Failure of multi-layer graphene coatings in acidic media

Being impermeable to all gases, graphene has been proposed as an effective ultrathin barrier film and protective coating. However, here it is shown how the gastight property of graphene-based coatings may indirectly lead to their catastrophic failure under certain conditions. When nickel coated with thick, high-quality chemical vapor deposited multilayered graphene is exposed to acidic solutions, a dramatic evolution of gas is observed at the coating-substrate interface. The gas bubbles grow and merge, eventually rupturing and delaminating the coating. This behavior, attributed to cathodic hydrogen evolution, can also occur spontaneously on a range of other technologically important metals and alloys based on iron, zinc, aluminum and manganese; this makes these findings relevant for practical applications of graphene-based coatings

Évolution des techniques en bijouterie

editorial reviewe

Real-time oxide evolution of copper protected by graphene and boron nitride barriers

Applying protective or barrier layers to isolate a target item from the environment is a common approach to prevent or delay its degradation. The impermeability of two-dimensional materials such as graphene and hexagonal boron nitride (hBN) has generated a great deal of interest in corrosion and material science. Owing to their different electronic properties (graphene is a semimetal, whereas hBN is a wide-bandgap insulator), their protection behaviour is distinctly different. Here we investigate the performance of graphene and hBN as barrier coatings applied on copper substrates through a real-time study in two different oxidative conditions. Our findings show that the evolution of the copper oxidation is remarkably different for the two coating materials