Wafer-scale lateral self-assembly of mosaic Ti₃C₂Tₓ MXene monolayer films
Experimental wafer-scale assembly of Ti₃C₂Tₓ MXene monolayers at a liquid–liquid interface is combined with ReaxFF MD (AMS/SCM) to rationalize flake–solvent interactions and interfacial stability.
Summary¶
A lateral self-assembly route deposits mosaic monolayer MXene films from immiscible solvents, with transfer to Si or glass yielding large-area films characterized by TEM/SEM/AFM, Raman mapping, ellipsometry, and sheet resistance. ReaxFF simulations probe MXene–solvent configurations relevant to interfacial trapping and energy trends that support assembly.
The abstract frames bottom-up assembly as requiring control of surroundings so interfacial energetics drive ordering, and states that ReaxFF MD clarifies flake–solvent interactions and stability at the immiscible liquid interface as a prerequisite for interfacial self-assembly. Multiscale characterization ties mosaic texture to uniform thickness, homogeneous optical response, and centimeter-scale electrical conductivity for transferred films.
Readers should verify numerical values, units, and section references against the peer-reviewed PDF and any Supporting Information, especially when extracts or galley PDFs truncate tables.
Methods¶
- Experiments: MXene processing, liquid–liquid assembly, substrate transfer, and multiscale structural/optical/electrical characterization (see article and Supporting Information).
- ReaxFF molecular dynamics (AMS suite, SCM): Ti₃C₂ MXene–chloroform/methanol/water chemistry modeled by extending the cited Ti₃C₂ MXene ReaxFF with Cl/C/H/O parameters and adjusted Ti/O/H terms for surface defects and (de)protonation kinetics (full parameter notes in SI Table S2 per the paper).
- Setup: Edge-terminated MXene slab equilibrated in bulk water at 500 K (NVT) to populate −OH terminations; adsorbed water stripped; solvents initialized in periodic cells (~43 × 46 × 17 ų) with MXene placed at the water–chloroform interface or within a solvent.
- Dynamics: NPT at P = 1 atm, T = 300 K for 1 ns (Berendsen barostat and thermostat with 5000 fs and 100 fs damping as stated); additional NPT 100 ps equilibration then NVT 500 ps production for energy statistics on orthogonalized edge-free slabs (26 × 30 Ų in-plane, 40 Å solvent slabs along z). Potential-energy running averages use a 150 ps window. Integration time step (fs), full E-field-driven (MV/cm) dynamics, and QEq update (ReaxFF): not fully transcribed on this page—N/A details; load the VOR + SI (including SI Table S2 for parameters). 2 — de novo ReaxFF fit paper: N/A (extends prior param set). 3 — static DFT-only headline: N/A. Shear, shock, umbrella, replica, metadynamics, hyperdynamics, CVHD, rare-event (unless the PDF names one): N/A (not in the excerpted bullets here). E-field in ReaxFF ( static / AC ) (MD): N/A (not part of this short list; the ACS Nano VOR + SI gives any E-field-in-FF notes if applicable).
Findings¶
- Wafer-scale films show high monolayer coverage, mosaic texture, and cm-scale conductivity relevant to device concepts.
- Simulations support that solvent–MXene interactions stabilize flakes at the immiscible liquid interface, consistent with the assembly mechanism.
- Bilayer/trilayer stacking from successive depositions is reported with correlated optical transmission and sheet resistance trends.
Corpus honesty: pdf_path uses a galley-dated filename; for definitive figures, Ω, and n-m-scale metrics, use the version-of-record ACS Nano file (and SI, e.g. S2 for ReaxFF notes).
Limitations¶
Galley-dated PDF filename; ReaxFF parameter extensions for chlorinated solvents are specialized—transferability to other MXene chemistries or edge states requires separate validation.
Relevance to group¶
van Duin co-authorship; ReaxFF parameterization and MD performed with FIRST EFRC acknowledgment in the article.