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Reversible intercalation of hexagonal boron nitride with Brønsted acids

Evidence and attribution

Authority of statements

Sections below summarize the publication identified by doi, title, and pdf_path in the front matter.

Summary

The work shows that stage-1 intercalation compounds of hexagonal boron nitride (h-BN) can be formed by thermal drying of h-BN in strong Brønsted acids (H₂SO₄, H₃PO₄, HClO₄), despite h-BN’s large band gap and limited redox intercalation chemistry compared to graphite. XPS, vibrational spectroscopy, electronic-structure modeling, and molecular dynamics support that noncovalent interactions—especially hydrogen bonding to basic N sites (and related polar interactions involving acid oxygens)—drive gallery uptake.

Methods

  • Materials preparation: h-BN microcrystal films are formed by drop casting from concentrated aqueous Brønsted acids and then thermally dried; the article screens multiple acids (H₂SO₄, H₃PO₄, HClO₄, HCl, HNO₃, CH₃COOH, HCOOH, C₆H₅SO₃H, H₂O) and reports stage-1 intercalation only for H₂SO₄, H₃PO₄, and HClO₄, with 00l spacings and gallery-height analysis tied to Figures 1–2 and Table S1 (Supporting Information).
  • Structural and spectroscopy: powder/film XRD tracks 00l reflections and interplanar spacings; XPS and vibrational spectroscopy characterize gallery composition and acid–sheet interactions in the Results section.
  • Thermal analysis: selected h-BN/ H₂SO₄ and h-BN/ H₃PO₄ suspensions are held isothermally at 130 °C and 120 °C, respectively, for 22 h to follow mass loss and dehydration pathways (Figure S1, Supporting Information); the text notes rapid initial ~11–12% water loss in the first hour, then slower mass loss with vapor-phase H₂O/acid ratio approaching equilibrium.
  • Theory: complementary electronic-structure calculations and molecular dynamics (functional/basis and MD protocol in the article and Supporting Information) interpret noncovalent acid–sheet interactions, emphasizing hydrogen bonding to basic N sites (and polar interactions involving acid O and lattice B discussed in the text).

MD / AIMD (theory)

Engine / code: Molecular dynamics (and related AIMD where employed) supports interpretation of noncovalent acid–BN interactions alongside electronic-structure models (abstract; pdf_path).

System & composition: N/A — simulation supercell stoichiometries and atom counts are not in normalized/extracts/2013bn-venue-ja403197h_p1-2.txt.

Boundaries / periodicity: N/A — PBC details for gallery models not excerpted here.

Ensemble (NVE / NVT / NPT): N/A — not stated in the indexed excerpt—read Computational sections of pdf_path / SI.

Timestep / duration / thermostat / barostat: N/A — not stated in the indexed excerpt—read Computational sections of pdf_path / SI.

Temperature / pressure: Experiments include isothermal holds at 130 °C (H₂SO₄) and 120 °C (H₃PO₄) for 22 h mass-loss tracks (Figure S1); N/A — thermostat settings for AIMD not in excerpt.

Electric field: N/A — not used in simulations as summarized here.

Replica / enhanced sampling: N/A — not stated.

Static QM (supporting electronic structure)

Functional / dispersion / basis / k-mesh: N/A — not recoverable from the short excerpt; pdf_path + SI carry the DFT setup.

Structures / pathways: h-BN galleries with Brønsted acids; hydrogen-bonding arrangements to N (and O–B polar contacts discussed in text).

Properties computed: Interlayer spacing, binding motifs, and spectroscopic correlates discussed vs XRD/XPS/vibrational data.

Findings

Outcomes: Stage-1 intercalates form for H₂SO₄, H₃PO₄, and HClO₄ after thermal drying of drop-cast films, with 00l spacings 7.4 Å, 6.9 Å, and 6.6 Å (gallery heights ~4.1, 3.6, and 3.3 Å above ~3.3 Å pristine h-BN, consistent with a single acid layer) (abstract/Results in pdf_path). Other acids screened in the excerpt list (HCl, HNO₃, acetic/formic/benzenesulfonic acids, water) do not yield the same stage-1 phases under the reported conditions.

Mechanism: XPS, vibrational spectroscopy, electronic-structure modeling, and MD support noncovalent uptake driven especially by hydrogen bonding to basic N (with O⋯B polar interactions noted in the text).

Sensitivity: Drying is required—wet films and non-dried liquid suspensions fail to develop the intercalate on the reported timelines.

Comparisons: Contrasts h-BN with redox-intercalated layered materials (graphite, TMDs) that are easier to oxidize/reduce intercalate (Introduction).

Limitations: Concentrated acid chemistry and disordered galleries complicate atomistic assignment from experiment alone; simulations are illustrative.

Corpus honesty: PDF lives under papers/ReaxFF_others/ for historical ingest reasons; methodology is DFT/AIMD-centric, not a ReaxFF paper despite the folder name.

Limitations

  • Complexity of concentrated acids and interlayer disorder limits atomistic assignment from experiment alone; simulations are illustrative of interactions rather than a full phase diagram.

Relevance to group

Useful corpus context for 2D insulators, intercalation chemistry, and acid–surface interactions; methodology is not centered on ReaxFF.

Citations and evidence anchors

  • Abstract and results discussion: intercalation chemistry and characterization (JACS; DOI above).