Aqueous proton transfer across single layer graphene

Evidence and attribution¶

Authority of statements

Prose below summarizes the text in the ingested pdf_path and extract. A fuller bibliographic record for the peer-reviewed article may appear under a different corpus slug; see Reader notes.

Summary¶

Experimental second-harmonic probing of silica beneath monolayer graphene on fused silica shows reversible protonation/deprotonation of silanols when the overlying aqueous pH is cycled, arguing for proton passage through the graphene. Macroscopic pinhole transport is argued against; permeation is attributed to rare atomic defects. Atomistic simulations reported in the manuscript describe comparatively facile water-mediated, Grotthuss-type pathways at hydroxyl-terminated defect motifs, while ether-bridged defects suppress exchange, and He/H transfer barriers are unfavorable—supporting selective aqueous proton permeation (abstract narrative; extract pages 1–2).

Methods¶

Experiments (SHG on silica through graphene)¶

Monolayer graphene on fused silica with bulk aqueous pH cycled at room temperature and constant ionic strength; interfacial second-harmonic generation (SHG) probes silanol protonation on the silica side (~120 fs pulses, pulse energies kept below graphene damage thresholds) (extract).

Excluding macroscopic pinholes¶

The article argues against pinhole-dominated transport using microscopy and permeation-order reasoning detailed in the full text (Summary).

Atomistic modeling (supporting interpretation)¶

Simulations compare water-mediated Grotthuss-type pathways at hydroxyl-terminated defect motifs versus blocked exchange for ether-bridged defect terminations, and discuss He/H transfer barriers as unfavorable relative to aqueous protons (Summary).

Canonical citation path¶

Peer-reviewed packaging is curated on [[2015achtyl-nat-aqueous-proton]]; use that entry for DOI, pagination, and figure references when available.

1 — MD application (atomistic simulations reported in the manuscript)¶

Engine / code, system sizes, ensembles, timesteps, thermostats, production lengths: N/A in this wiki summary—the ingested Achtyl_graphene_proton_archive.pdf excerpt used here does not spell out full MD control parameters; read the Nature Communications article on [[2015achtyl-nat-aqueous-proton]] (and SI) for authoritative simulation settings.
Replica / enhanced sampling: N/A — not stated in the excerpt summarized here.

2 — Force-field training¶

N/A — not a parameterization study.

3 — Static QM¶

N/A — the excerpt-level summary emphasizes classical/DFT-hybrid-style modeling narratives as interpreted in the paper; confirm electronic-structure details in the version-of-record PDF.

Findings¶

1 — Outcomes and mechanisms¶

Cycling pH produces reversible protonation/deprotonation of interfacial silanols probed by SHG, interpreted as protons traversing the monolayer to participate in acid–base chemistry at the silica. After excluding pinhole-dominated transport, permeation is attributed to rare atomic defects. The modeling narrative distinguishes low-energy water-mediated pathways at certain defect terminations from blocked exchange for ether-bridged motifs, supporting selective aqueous proton permeation through an otherwise inert sheet (abstract narrative; extract pages 1–2).

2 — Comparisons¶

Experiment (SHG) vs pinhole transport hypotheses; atomistic scenarios compared qualitatively for defect terminations (article narrative in excerpt).

3 — Sensitivity¶

Aqueous pH cycling at room temperature drives the SHG response reported in the excerpt.

4 — Limitations / outlook¶

Archive PDF vs version-of-record packaging; see ## Limitations.

5 — Corpus / KB honesty¶

This slug’s pdf_path is an archive/working PDF; canonical DOI, venue, and pagination live on [[2015achtyl-nat-aqueous-proton]]. Evidence anchors: normalized/extracts/2014geiger-venue-paper_p1-2.txt.

Limitations¶

The ingested file is an archive/working PDF (Achtyl_graphene_proton_archive.pdf), not the Nature Communications version of record; cite the published article for definitive metadata.

The peer-reviewed article for this work is curated as 2015achtyl-nat-aqueous-proton (DOI 10.1038/ncomms7539). Use that page for venue, pagination, and canonical citation strings.

Citations and evidence anchors¶

Extract normalized/extracts/2014geiger-venue-paper_p1-2.txt (pages 1–2 of ingested PDF).