pith. sign in

arxiv: 2604.27114 · v1 · submitted 2026-04-29 · ❄️ cond-mat.mtrl-sci

Contrasting Effects of Functionalization in Binary and Medium-Entropy MXene Coatings for Corrosion Protection

Aqsa Fayyaz , Ulises Martin Diaz , Jianyu Dai , Homero Castaneda , Chenglin Wu This is my paper

Pith reviewed 2026-05-07 10:06 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords MXenecorrosion protectionanticorrosion coatingsmedium-entropy materialssurface functionalizationelectrochemical impedance spectroscopydensity functional theorysteel infrastructure
0
0 comments X

The pith

Functionalized medium-entropy MXenes outperform binary ones in multilayer anticorrosion coatings for steel.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper tests nacre-inspired multilayer epoxy coatings reinforced with four different MXene systems on steel exposed to chloride. It finds that the layered structure raises electrical resistance by five orders of magnitude and that phosphorus-terminated medium-entropy MXene performs best. Density functional theory links the ranking to how each surface adsorbs oxygen and forms protective oxides. The work shows that surface termination and compositional entropy together control ion blocking in these barrier coatings.

Core claim

A nacre-inspired multilayer epoxy coating reinforced with P-(TiVCrMo)C3 MXene reaches coating resistances of 10^8 Ohm/cm2 because its multi-metal electronic structure strongly adsorbs oxygen-containing species and promotes stable protective oxides, while binary Ti3C2Tx with oxygen termination ranks second and phosphorus-terminated binary MXene ranks lowest due to higher surface reactivity.

What carries the argument

The nacre-inspired lamellar network of epoxy layers interleaved with functionalized MXene sheets, which lengthens diffusion paths for corrosive ions while the MXene surfaces interact electrochemically with oxygen species.

If this is right

  • The observed performance order supplies a concrete rule for choosing MXene composition and termination when designing barrier coatings.
  • Multilayer stacking can be applied to other 2D fillers to achieve similar tortuosity gains in polymer matrices.
  • The link between entropy-driven adsorption and oxide formation points to compositional tuning as a lever for corrosion protection.
  • Electrochemical impedance data at early times already predicts which variant will maintain barrier properties longest.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same termination and entropy effects could be tested in coatings for aluminum or magnesium alloys in acidic media.
  • If defects dominate after prolonged exposure, adding self-healing additives to the epoxy would be a logical next engineering step.
  • The approach suggests that high-entropy 2D materials may improve other functional coatings such as thermal barriers or anti-fouling layers.
  • Scaling the multilayer process to large panels would require verifying that the lamellar alignment survives industrial application methods.

Load-bearing premise

That the calculated adsorption strengths of oxygen on the MXene surfaces fully account for the measured long-term resistance without defects, poor adhesion, or unmodeled ion pathways through the coating.

What would settle it

A months-long salt-spray or immersion test in which the P-(TiVCrMo)C3 coating loses its resistance advantage and fails at the same rate as the binary MXene coatings.

read the original abstract

Developing scalable and environmentally benign anticorrosion coatings is critical for protecting steel infrastructure in chloride-rich environments. Here, a nacre-inspired multilayer epoxy coating reinforced with four MXene systems is investigated. This architecture forms a dense lamellar network that increases diffusion tortuosity and introduces electroactive surfaces for ion interactions. Electrochemical impedance spectroscopy (EIS) confirms that the multilayer design increases coating resistance from ~103 to ~108 Ohm/cm2. A clear performance hierarchy was observed: P-(TiVCrMo)C3 > O-Ti3C2Tx > O-(TiVCrMo)C3 > P-Ti3C2Tx. Density functional theory (DFT) calculations reveal that P-Ti3C2 strongly adsorbs O2, indicating higher surface reactivity, while oxygen termination stabilizes the surface by partially passivating Ti sites. In contrast, P-(TiVCrMo)C3 exhibits strong adsorption of oxygen-containing species due to its multi-metal electronic structure, promoting the formation of protective oxides. These results highlight the delicate balance of surface chemistry, electronic structure, and compositional entropy in designing next-generation MXene-based anticorrosion coatings for marine and industrial environments.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates nacre-inspired multilayer epoxy coatings reinforced with four MXene systems (P-(TiVCrMo)C3, O-Ti3C2Tx, O-(TiVCrMo)C3, P-Ti3C2Tx). EIS measurements show coating resistance increasing from ~10^3 to ~10^8 Ohm/cm² with the hierarchy P-(TiVCrMo)C3 > O-Ti3C2Tx > O-(TiVCrMo)C3 > P-Ti3C2Tx. DFT calculations on O2 and oxygen-species adsorption are invoked to explain the ranking via surface reactivity, passivation, and protective oxide formation in the medium-entropy system.

Significance. If the asserted link between DFT adsorption trends and long-term EIS resistance holds after addressing real-coating factors, the work would usefully illustrate how compositional entropy and surface termination can be tuned to improve MXene-based anticorrosion barriers. The nacre-inspired lamellar design for tortuosity enhancement is a constructive architectural approach with potential relevance to marine steel protection.

major comments (2)
  1. [Abstract / Results] Abstract and Results: The performance hierarchy and resistance gain are stated without raw EIS spectra, Nyquist/Bode plots, error bars, replicate numbers, or statistical tests confirming that the observed order is significant rather than within experimental scatter. This is load-bearing for the central experimental claim.
  2. [DFT Calculations] DFT section: The manuscript claims that ideal-surface adsorption energies (strong O2 adsorption on P-Ti3C2, strong oxygen-species adsorption on P-(TiVCrMo)C3) directly account for the EIS-measured resistance order, yet provides no quantitative correlation, sensitivity analysis, or modeling of how these energies dominate over lamellar defects, epoxy-MXene adhesion, or long-range ion diffusion paths. Without such bridging, the DFT hierarchy cannot be shown to predict the macroscopic impedance after extended exposure.
minor comments (2)
  1. [Abstract] Notation: Use consistent scientific notation (10^3 rather than ~103) and define all acronyms (EIS, DFT) on first use in the main text.
  2. [Results] Consider adding a summary table of fitted EIS parameters (R_ct, CPE, etc.) for the four coatings to allow direct comparison.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We are grateful to the referee for the thorough review and insightful comments on our manuscript. We address each of the major comments below and outline the revisions we plan to make to strengthen the paper.

read point-by-point responses

  1. Referee: [Abstract / Results] Abstract and Results: The performance hierarchy and resistance gain are stated without raw EIS spectra, Nyquist/Bode plots, error bars, replicate numbers, or statistical tests confirming that the observed order is significant rather than within experimental scatter. This is load-bearing for the central experimental claim.

    Authors: We agree that the presentation of the EIS data in the original manuscript could be improved for greater transparency and rigor. While the hierarchy is supported by the measurements, we did not include the full set of raw spectra, plots with error bars, or explicit statistical analysis in the main text. In the revised version, we will add representative Nyquist and Bode plots from multiple replicates (n=3), include error bars, and provide a statistical confirmation of the significance of the performance order. This will directly address the concern and bolster the central claim. revision: yes

  2. Referee: [DFT Calculations] DFT section: The manuscript claims that ideal-surface adsorption energies (strong O2 adsorption on P-Ti3C2, strong oxygen-species adsorption on P-(TiVCrMo)C3) directly account for the EIS-measured resistance order, yet provides no quantitative correlation, sensitivity analysis, or modeling of how these energies dominate over lamellar defects, epoxy-MXene adhesion, or long-range ion diffusion paths. Without such bridging, the DFT hierarchy cannot be shown to predict the macroscopic impedance after extended exposure.

    Authors: The referee correctly identifies a gap in our bridging between the atomic-scale DFT results and the macroscopic EIS observations. Our DFT calculations on ideal surfaces were meant to elucidate the underlying surface chemistry and reactivity trends that align with the experimental performance ranking, particularly highlighting the role of compositional entropy in the medium-entropy MXene. However, we acknowledge the absence of quantitative correlation or explicit modeling of defects and diffusion paths. In the revision, we will add a dedicated paragraph discussing these limitations, note that the DFT provides supportive mechanistic insight rather than a complete predictive model, and include any feasible sensitivity analysis (such as adsorption on representative defect sites). We believe this will clarify the connection without overclaiming. revision: partial

Circularity Check

0 steps flagged

No circularity; experimental EIS hierarchy and DFT adsorption results are independent components

full rationale

The paper presents EIS measurements as direct experimental observations of coating resistance increase (~10^3 to ~10^8 Ohm/cm2) and the performance order P-(TiVCrMo)C3 > O-Ti3C2Tx > O-(TiVCrMo)C3 > P-Ti3C2Tx. DFT calculations are described separately as revealing adsorption energies and surface passivation effects that align with the observed order. No equations, fitted parameters renamed as predictions, self-citations, or ansatzes are invoked that would reduce the central claims to their own inputs by construction. The chain consists of independent experimental data and computational interpretation without self-referential reduction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The abstract relies on standard assumptions of DFT for surface adsorption and EIS for coating resistance; no new free parameters, invented entities, or ad-hoc axioms are introduced beyond domain-standard methods.

axioms (1)
  • domain assumption DFT adsorption energies for O2 and oxygen species on MXene surfaces correlate directly with observed corrosion protection performance
    Invoked to interpret why P-(TiVCrMo)C3 outperforms the others

pith-pipeline@v0.9.0 · 5521 in / 1266 out tokens · 77220 ms · 2026-05-07T10:06:50.840137+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

4 extracted references · 4 canonical work pages

  1. [1]

    Thin nacre-biomimetic coating with super-anticorrosion performance

    (1) Zhang, Y .; Tian, J.; Zhong, J.; Shi, X. Thin nacre-biomimetic coating with super-anticorrosion performance. ACS nano 2018, 12 (10), 10189–10200. (2) Wang, L.; Wang, X.; Liu, T.; Sun, F.; Li, S.; Geng, Y .; Yao, B.; Xu, J.; Fu, J. Bio-inspired self- healing and anti -corrosion waterborne polyurethane coatings based on highly oriented graphene oxide. n...

    work page 2018

  2. [2]

    The influence of graphene on the cathodic protection performance of zinc-rich epoxy coatings

    (3) Bai, W.; Ma, Y .; Meng, M.; Li, Y . The influence of graphene on the cathodic protection performance of zinc-rich epoxy coatings. Progress in Organic Coatings 2021, 161, 106456. (4) Qiang, Y .; Guo, L.; Li, H.; Lan, X. Fabrication of environmentally friendly Losartan potassium film for corrosion inhibition of mild steel in HCl medium. Chemical Enginee...

    work page 2021

  3. [3]

    A composite coating based on Ti3C2Tx MXene and M16 corrosion inhibitor for self -healing anti- corrosion and wear resistance

    (13) Li, C.; Liu, Y .; Yu, Q.; Sun, S.; Liu, S.; Zhao, C.; Wang, X.; Yang, S.; Yu, B.; Cai, M. A composite coating based on Ti3C2Tx MXene and M16 corrosion inhibitor for self -healing anti- corrosion and wear resistance. Surface and Coatings Technology 2024, 476, 130281. (14) Ning, Y .; Song, Y .; Li, S.; Wu, S.; Wang, Q.; Tian, H.; Liu, B. Nanocontainers...

    work page 2024

  4. [4]

    Air -stable titanium carbide MXene nanosheets for corrosion protection

    (23) Zhao, H.; Ding, J.; Zhou, M.; Yu, H. Air -stable titanium carbide MXene nanosheets for corrosion protection. ACS Applied Nano Materials 2021, 4 (3), 3075–3086

    work page 2021