Effect of metal ion intercalation on the structure of MXene and water dynamics on its internal surfaces (proof PDF)
Summary¶
MXene electrodes intercalate ions and water between exfoliated transition-metal carbide layers, coupling electrochemical performance to nanoconfined hydration dynamics and interlayer structural coherence. Hydroxyl-, oxygen-, and fluorine-terminated surfaces make MXenes hydrophilic, so interlayer water and cations can strongly affect electrochemical response in realistic humid environments. This ACS Applied Materials & Interfaces letter combines laboratory X-ray diffraction, small-angle neutron scattering, and quasielastic neutron scattering on Ti₃C₂Tₓ MXene with ReaxFF molecular dynamics to interrogate how potassium-ion intercalation alters c-axis stacking, morphological homogeneity, and water mobility inside galleries. After vacuum annealing at 110 °C, the published letter reports layer-to-layer repeat distances near 19.64 Å for pristine MXene and near 24.35 Å for K⁺-intercalated material, with a sharper 0001-like diffraction peak for the intercalated case interpreted as larger and/or more ordered stacked domains. Scanning electron microscopy images in the supporting material are cited as consistent with more uniform nanoscale stacking after intercalation. Quasielastic neutron scattering and simulations both indicate orders-of-magnitude reduction in confined water self-diffusion upon K⁺ intercalation, which the authors connect to improved environmental stability under changing humidity. This wiki slug records an author-proof PDF; [[2016osti-venue-am6b01490]] should be used for version-of-record pagination and figures when both files are available.
Methods¶
Author-proof PDF for the MXene + confined-water letter curated on 2016osti-venue-am6b01490 (DOI 10.1021/acsami.6b01490). Experiments match the issue letter (post-anneal \(c\)-axis repeats near 19.64 Å versus 24.35 Å after 110 °C drying, plus SANS/QENS as published). Companion ReaxFF molecular dynamics in LAMMPS uses the SI-documented 0.25 fs timestep, NPT relaxations (10 ps, 300 K, 0.1 MPa) between GCMC moves, and 1.5 ns NVT segments for confined-water MSD/diffusivity comparisons—see 2016osti-venue-microsoft-word for the ASCII tables. Periodic hydrated supercells follow the same construction rules as the issue PDF. Do not read thermostat coupling constants from this proof layout; use the SI LAMMPS deck. N/A — new force-field training or standalone static QM beyond the published parametrization story.
Findings¶
K\(^+\) intercalation increases interlayer spacing, yields sharper 000ℓ diffraction than pristine MXene after comparable drying/annealing, and is interpreted as larger, more homogeneous stacked domains (SEM motifs in SI support uniformity narratives in the letter). SANS trends align with more homogeneous swelling. QENS and ReaxFF both report strongly suppressed interlayer water mobility upon intercalation (authors quote ~two orders of magnitude lower self-diffusion in MD for the intercalated case relative to pristine in the published comparison). Together, the data argue that cation and water content tune both structural coherence and nanoconfined hydration dynamics—use [[2016osti-venue-am6b01490]] for exact factors and discussion of humidity stability.
Comparisons and sensitivity. Compared to pristine MXene, intercalated samples show sharper diffraction, distinct SANS slopes, and slower QENS relaxation; temperature history (110 °C vacuum anneal) is a shared experimental knob between batches.
Limitations and corpus honesty. Proof PDFs can differ cosmetically from the version-of-record; cite 2016osti-venue-am6b01490 for authoritative figures. Future work implied by the letter—broader humidity cycling and additional cations—is not expanded on this duplicate page.
Limitations¶
Proof PDFs may exhibit editorial markup and layout differences; cite the issue PDF for authoritative figure labels. Force-field models of interfacial water cannot capture all quantum tunneling or proton-transfer effects relevant at the lowest temperatures.
Relevance to group¶
The entry documents duplicate corpus bytes for a van Duin-coauthored ReaxFF plus neutron-scattering MXene study, routing operators to the canonical slug for DOI 10.1021/acsami.6b01490.
MAS / retrieval notes¶
Prefer [[2016osti-venue-am6b01490]] for stable figure numbering; when answering about intercalation-induced water slowdown, cite both QENS observables and ReaxFF diffusion metrics from the parent article rather than this proof PDF alone. Keywords water-interfaces, 2d-materials, and galley-or-proof-pdf should surface this page only with the duplicate-ingest warning. Automated pipelines should not merge duplicate manifests without reconciling pdf_sha256 values across proof and issue files.