Adsorption of L-proline nitrate modified graphene oxide on iron surface: Density functional theory and Monte Carlo simulation study

The adsorption mechanism corroborating the corrosion inhibition effects of graphene oxide (GO) modified with L-proline nitrate (ProNit) ionic liquid, ProNit-GO, on iron surface was investigated using ab initio density functional theory (DFT) and Monte Carlo (MC) simulation techniques. The electronic density distribution along with various electronic properties, including frontier molecular orbitals primarily highest occupied molecular orbital, lowest unoccupied molecular orbitals, energy gap, reactivity, and hydrogen bonding interactions between L-proline nitrate and graphene oxide stabilizing ProNit-GO adduct interacting through different sites of interactions, were examined through DFT calculation which revealed different reactive sites within ProNit-GO and its reactivity. Additionally, the MC simulation investigation of ProNit-GO on iron surface has unveiled its remarkable propensity for spontaneous interaction and favored adsorption energetically ascertained from the highly negative magnitude of adsorption energy. Furthermore, MC simulation results revealed a horizontally aligned disposition of ProNit-GO onto targeted Fe(110) surface suggesting the adsorption of ProNit-GO onto iron surface and protective film formation. The adsorbed ProNit-GO acted as barrier layer that inhibit the penetration of corrosive electrolytes or species towards the susceptible iron surface exposed into the corrosive electrolyte. Hence, the corrosion inhibitory effects of ProNit-GO on iron surface can be deliberated upon.