Graphene as a corrosion-inhibiting coating for metals: a molecular dynamics study

摘要

The intensely-packed, honeycomb structure of graphene has made it impermeable to all molecules and has attracted a growing attention for its potential application as an anti-corrosion coating for metals. Although graphene has shown promising potentials for corrosion inhibition, some challenges need to be resolved before it finds application in practice. One of these challenges is the galvanic coupling that occurs at the graphene-metal interface and is promoted by the cracks and defects that appear over time on the surface of graphene. Such corrosion mechanism is attributed to the nobility of graphene compared with most common metals in the galvanic sequence that could lead to localized corrosion and consequently weaken the coated metals. Research efforts on the corrosion protection of metals using graphene have primarily been limited to laboratory experiments, and numerical studies should be carried out to gain insight into the corrosion inhibition mechanism of graphene and investigate the scenarios that are difficult to achieve in the laboratory. Acknowledging this need, this study reports the results of an extensive series of molecular dynamics (MD) simulations that are carried out to study the corrosion mechanism in uncoated and graphene-coated copper samples at different temperatures. The binding energy on the corroded surface and weight loss of copper samples are monitored to evaluate the effectiveness of the corrosion inhibition of coatings. Results indicate that copper samples coated with defect-free graphene achieve equilibrium at 44% less binding energy compared with uncoated copper and, on average, 29% less binding energy compared with copper samples coated with defective graphene.