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Burning Graphene Layer-by-Layer

Summary

Oxidation resistance of graphene and few-layer graphite is central to high-temperature electronics and processing, yet controlled thinning without basal-plane damage remains difficult: many methods yield nonuniform etching or introduce defects. This paper reports low-power laser heating of multi-layer graphene (MLG) in air in a cold-wall configuration—only the sample is hot while the surrounding gas stays near room temperature—reaching temperatures exceeding 2000 K on suspended flakes without immediate burnout. Under these conditions, layer-by-layer oxidative thinning proceeds with comparatively uniform in-plane etching. Supported samples on substrates, by contrast, burn nonuniformly at much higher rates. Fully atomistic reactive molecular dynamics with ReaxFF-class chemistry interprets oxidation and gasification microsteps that produce the observed uniform removal versus rapid localized attack.

Methods

Experiment

MLG from sonicated natural graphite on TEM grids compares suspended flakes to supported samples. Low-power laser heating in air uses a cold-wall arrangement (sample hot, gas not furnace-hot). SEM tracks in-plane versus normal etching; Raman and related optics estimate local peaks ~>2000 K on suspended material.

MD application (atomistic dynamics)

LAMMPS with combustion-oriented ReaxFF (Sci. Rep.) models multi-layer graphene in an atomic oxygen atmosphere under PBC, intended to mimic the low gas-temperature limit of the cold-wall experiments. NVT sampling with a Nose–Hoover thermostat spans 800–3000 K with 0.1 fs steps over ~150 ps typical runs; supercell sizes are in papers/ReaxFF_others/Ermakov_Paupitz_etal_SciRep_GraphOx_2015.pdf. Shear, shock, applied electric field, NPT barostat: N/A — not used in the described gas-phase oxidation setup.

Force-field training

N/A — applies an existing ReaxFF combustion parameterization (cited in the PDF) rather than reporting a new fit.

Static QM / DFT

N/A — not the primary modality for the oxidation trajectories summarized here.

Findings

Suspended MLG thins layer-by-layer in air under cold-wall laser heating at very high local T, while supported flakes oxidize faster and nonuniformly (SEM shows localized holes)—a direct experiment contrast in morphology and etching rate. ReaxFF trajectories support basal-plane oxidation/gasification chemistry consistent with an atomic-oxygen, cold-wall-like environment, linking decomposition microsteps to uniform removal versus localized attack. Sensitivity to temperature (800–3000 K in simulation) and to substrate support is central to the narrative. Limitations include simplified laser–plasma chemistry and ReaxFF’s approximate O₂ excitation physics; see the PDF for quantitative Raman/SEM claims.

Limitations

Laser–plasma chemistry and defect distributions in real flakes are simplified; ReaxFF captures combustion-like bond rearrangements but not explicit electronic excitations of O₂ under laser irradiation.

Relevance to group

Couples graphene high-temperature oxidation experiments with reactive MD interpretation for combustion-adjacent carbon chemistry.

Citations and evidence anchors