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Atomistic insights into the protection failure of the graphene coating under hyperthermal impacts of reactive oxygen species

Summary

Amiri et al. use ReaxFF molecular dynamics to study hyperthermal impacts of atomic oxygen, O\(_2\), and O\(_3\) on graphene-covered Ni(111), quantifying how effectively graphene protects the metal from oxidation when incident energies reach 10–30 eV. The scenario is intentionally nonthermal: it resembles beam-like delivery of ROS rather than ambient oxidation, making it relevant to plasma and space-environment damage questions as well as to conceptual limits of 2D coatings. The authors define protection degree metrics and interpret outcomes with Wigner–Seitz-style diagnostics on Ni to track substrate damage, alongside structural indicators for graphene disorder and NiO formation. The narrative advances a three-stage mechanism—defect formation in graphene, Ni transport across the interface, and NiO growth over disordered carbon—to explain how protection fails as energy rises.

Methods

  • N/A as a new parametrization in this work: the study applies a published ReaxFF for C/H/O/Ni-class chemistry as described in Appl. Surf. Sci. (see pdf_path for the exact force-field lineage and any QM benchmarks cited for Ni/graphene oxidation).

B — Molecular dynamics, experiments, protocols, and sampling

ReaxFF MD in LAMMPS-class workflows compares bare and graphene-covered Ni(111) under normal hyperthermal incidence of O, O\(_2\), and O\(_3\) at 10, 20, and 30 eV (nonthermal beam-like energy deposition). 3D PBC slab supercells; sub-1 fs timestep; ps-scale (or as stated) trajectory stages after any preequilibration; NVE/NVT per the Appl. Surf. Sci. Methods; thermostat and K-scale substrate temperature (if a thermal bath is used)—see pdf_path for the precise recipe. Barostat and isotropic 1 bar pressure—N/A in the open impact regime if the cell is not NPT-relaxed. Shear and piston shock—N/A in the baseline normal-incidence impacts described. External DC electric field in the impact protocol—N/A in the abstract-level summary. Umbrella / replica—N/A. Analysis includes Wigner–Seitz defect counting for Ni to quantify substrate oxidation/reordering, protection degree metrics, and sp² vs disordered carbon and NiO signatures.

C — Electronic structure / static QM (when reported separately from MD)

  • Not applicable / not separated here: QM used only as ReaxFF training data may be documented under §A in the article rather than as standalone §C.

D — Review scope, SI/galley notes, and non-primary corpus roles

  • Not applicable: primary research article unless the Summary flags a review, SI-only register, or duplicate PDF (see Reader notes / Limitations).

Findings

Pristine graphene on Ni(111) can block O\(_2\) and O\(_3\) at 10 eV, but fails partially at 20–30 eV, with reported protection degrees around 53–55% for O\(_2\) and 41–48% for O\(_3\) depending on energy. Atomic O at 10 eV yields about 59% protection, falling to ~22% at 20 eV and ~6% at 30 eV, including regimes described as anti-protective when oxidation is catalyzed through damaged graphene. Graphene can evolve from crystalline sp² networks toward disordered carbon coexisting with amorphous NiO after sustained hyperthermal exposure in the authors’ trajectories. Comparisons of bare versus coated Ni(111) and of O versus O₂/O₃ at the same incident energy isolate when the coating is protective versus anti-protective. Sensitivity to energy (10–30 eV) and ROS identity controls the degree of Ni oxidation and graphene disorder. Limitations of the classical model and future work toward experiment-anchored flux scenarios are discussed in the article and in ## Limitations below. Corpus honesty: quote numerical protection percentages from the version-of-record PDF at pdf_path, not from this wiki alone.

Limitations

Hyperthermal conditions differ from thermal oxidation; ReaxFF limits quantitative sputter and electronic excitation details. Readers comparing to plasma diagnostics should remember that beam-energy inputs here are not a substitute for flux-weighted thermal oxidation models.

Reader notes (navigation)

This entry pairs with graphene–metal oxidation pages and with tribology notes that emphasize shear rather than impact loading; keep canonical_tags distinct to reduce retrieval collisions in theme hubs.

Relevance to group

External ReaxFF application to graphene–metal oxidation under extreme ROS impact conditions.

Citations and evidence anchors