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arxiv: 2606.12110 · v1 · pith:RQHYNPNFnew · submitted 2026-06-10 · ❄️ cond-mat.mtrl-sci

Scalable Conformal MoSx Catalyst for Efficient Hydrogen Evolution at Industrial-Level Current Density in Alkaline Electrolyzers

Yong Zuo , Sebastiano Bellani , Meysoun Jabrane , Gabriele Saleh , Thi-Hong-Hanh Le , Michele Ferri , Davide Salusso , Zhanzhao Li
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Valentina Mastronardi Marilena I. Zappia Manjunath Chatti Mirko Prato Silvia Dante Francesco Bonaccorso Yongsheng Han Liberato Manna
This is my paper

Pith reviewed 2026-06-27 08:48 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords MoS3 catalysthydrogen evolution reactionalkaline water electrolyzernickel foamconformal coatingedge-sulfur sitesindustrial current densityscalable fabrication
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The pith

A coating-annealing process creates MoS3 on nickel foam that sustains alkaline electrolysis at 1 A/cm² and 1.96 V for 1000 hours.

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

The paper presents a simple coating followed by annealing to deposit a conformal MoSx layer on porous nickel foam and shows how adjusting the annealing step shifts the layer from MoS2 to MoS3. The resulting MoS3@NF electrode reaches 200 mA/cm² at 246 mV overpotential for hydrogen evolution in alkaline electrolyte and remains stable for more than 240 hours. When paired with a stainless-steel anode in a full alkaline water electrolyzer cell, the same cathode maintains 1 A/cm² at 1.96 V for 1000 hours, exceeding most prior MoSx-based devices. The authors attribute the performance to abundant edge-sulfur atoms that act as active sites. This combination of scalable fabrication and industrial-level metrics is offered as evidence that MoS3 can serve as a practical cathode for large-scale alkaline electrolysis.

Core claim

By controlling the annealing step after coating, the composition of the MoSx layer on nickel foam can be tuned to MoS3, whose abundant edge-sulfur atoms function as active sites for the hydrogen evolution reaction; the resulting MoS3@NF cathode delivers 200 mA/cm² at 246 mV overpotential, operates stably for over 240 h in half-cell tests, and, when combined with a stainless-steel anode, enables a complete alkaline water electrolyzer to run continuously at 1 A/cm² and 1.96 V for 1000 h.

What carries the argument

The conformal MoS3 layer on porous nickel foam, whose edge-sulfur atoms serve as the active sites for alkaline HER and whose composition is set by the annealing step.

If this is right

  • MoS3@NF reaches industrially relevant 200 mA/cm² at only 246 mV overpotential in alkaline media.
  • The electrode maintains stable hydrogen evolution for more than 240 hours at high current density.
  • A complete alkaline electrolyzer using this cathode and a stainless-steel anode sustains 1 A/cm² at 1.96 V for 1000 hours.
  • The performance exceeds that of most previously reported MoSx-based water electrolyzers.
  • The coating-annealing route is presented as a scalable route to cost-effective cathodes for alkaline water electrolyzers.

Where Pith is reading between the lines

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

  • If the edge-sulfur sites remain active after prolonged operation, the same annealing control could be applied to other porous substrates to increase active surface area further.
  • The 1000-hour full-cell result implies that MoS3 may reduce the need for platinum-group metals in alkaline electrolyzers, but only if the nickel-foam substrate itself survives industrial cycling without degradation.
  • A direct comparison of edge-site density before and after 1000 hours would test whether the claimed active-site mechanism persists at scale.

Load-bearing premise

The reported overpotentials, current densities, and 1000-hour stability values were measured under conditions that match industrial operation and that the annealing step reliably produces the claimed MoS3 composition with abundant edge-sulfur sites in every batch.

What would settle it

A replicate electrode that, after the same coating-annealing sequence, shows either a different sulfur-to-molybdenum ratio by XPS or fails to hold 1 A/cm² at or below 1.96 V for more than a few hundred hours.

Figures

Figures reproduced from arXiv: 2606.12110 by Davide Salusso, Francesco Bonaccorso, Gabriele Saleh, Liberato Manna, Manjunath Chatti, Marilena I. Zappia, Meysoun Jabrane, Michele Ferri, Mirko Prato, Sebastiano Bellani, Silvia Dante, Thi-Hong-Hanh Le, Valentina Mastronardi, Yongsheng Han, Yong Zuo, Zhanzhao Li.

Figure 1
Figure 1. Figure 1: Catalysts synthesis and morphological characterizations (A) Preparation scheme. (B) photographs of electrodes prepared using different porous substrates. (C) SEM images of blank NF. (D) SEM images of MoSx@NF at different magnifications. (E) SEM-EDS elemental mappings of MoSx@NF, showing the distribution of Mo and S elements. Spectral Characterizations and Analyses [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Electrochemical characterization of the electrodes in three-electrode cell configuration (A) iR-corrected linear sweep voltammetry (LSV) curves of various electrodes, including blank NF, Pt/C￾CPR benchmark (100 μgPt/cm²), and different MoSx@NF electrodes. (B) Δj/2 vs. scan rate plot extracted from corresponding CV curves at -0.81 V vs. Hg/HgO, used for ECSA calculation. (C) ECSA-normalized iR-corrected LSV… view at source ↗
read the original abstract

The development of simple and scalable fabrication strategies for cost-effective electrodes is crucial to advance water splitting in alkaline water electrolyzers (AWEs). Here, we present a coating-annealing method to conformally coat a MoSx catalyst layer onto a porous Ni foam (NF) substrate. By controlling the annealing process, the composition of the MoSx layer could be tuned from MoS2 to MoS3 and its catalytic performance for hydrogen evolution reaction (HER) in alkaline media was optimized. The MoS3@NF synthesized by this method achieved industrially relevant HER current densities of 200 mA/cm2 at a low overpotential of 246 mV, maintaining stable operation for over 240 h. The MoS3@NF cathode, combined with a stainless steel anode, enabled an alkaline water electrolyzer (AWE) cell to operate steadily at 1.96 V and 1 A/cm2 for 1000 h. This performance surpasses that of most of the previously reported water electrolyzers employing MoSx-based cathodes. Our work demonstrates the potential of MoS3 (with its abundant edge-sulfur atoms serving as active sites) as a high-performance cathode material for industrial AWEs.

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

4 major / 2 minor

Summary. The manuscript reports a coating-annealing fabrication method to conformally deposit a tunable MoSx layer on porous Ni foam. By adjusting the annealing step the composition is shifted from MoS2 to MoS3; the resulting MoS3@NF cathode delivers 200 mA cm⁻² at 246 mV overpotential in alkaline HER and remains stable for >240 h. When paired with a stainless-steel anode in a two-electrode alkaline water electrolyzer the cell sustains 1.96 V at 1 A cm⁻² for 1000 h, stated to exceed most prior MoSx-based devices. The work attributes the activity to abundant edge-sulfur sites in MoS3 and positions the approach as a scalable route for industrial AWEs.

Significance. If the reported half-cell and full-cell metrics are reproducible and the MoS3 phase assignment is confirmed by quantitative characterization, the result would be significant for the field. A simple, scalable route to a non-precious-metal cathode that meets industrial current density with 1000-hour stability directly addresses a key barrier to alkaline electrolyzer deployment. The long-duration full-cell demonstration is a strength that, if properly documented, would strengthen the practical relevance of MoSx catalysts.

major comments (4)
  1. [Experimental Methods] Experimental Methods (annealing protocol): the temperature, duration, and atmosphere of the annealing step that is asserted to produce phase-pure MoS3 with abundant edge-S sites are not specified, preventing reproduction and verification that the claimed composition (rather than a MoS2/MoS3 mixture) is obtained across batches.
  2. [Results] Results (catalyst characterization): no XPS survey or high-resolution spectra, no S/Mo elemental ratios from EDS or ICP, and no reference to any quantitative phase analysis are supplied to substantiate the statement that the annealed layer is MoS3 whose edge-sulfur atoms are the dominant active sites.
  3. [Electrochemical Measurements] Electrochemical section / full-cell data: the two-electrode AWE test at 1 A cm⁻² / 1.96 V lacks any description of iR compensation method, reference-electrode placement (if used), KOH concentration and temperature, membrane/separator type, or confirmation that current density is reported on true geometric area without excessive ohmic losses; these omissions directly affect the validity of the industrial-relevance and “surpasses most prior MoSx” claims.
  4. [Results] Stability data presentation: the 1000 h full-cell run and the 240 h half-cell run are reported without error bars, number of replicates, or criteria for data exclusion, making it impossible to assess whether the headline metrics are statistically representative.
minor comments (2)
  1. [Abstract] The abstract states that performance “surpasses that of most of the previously reported water electrolyzers employing MoSx-based cathodes” but supplies no explicit benchmark table or cited references for that comparison; a supplementary table collating overpotentials, current densities, and stability metrics from the literature would strengthen the claim.
  2. [Throughout] Notation for current density (mA/cm2 vs mA cm⁻²) is inconsistent between the abstract and the body; uniform SI-style formatting should be adopted throughout.

Simulated Author's Rebuttal

4 responses · 0 unresolved

We thank the referee for the constructive comments and for recognizing the potential significance of the scalable fabrication approach and long-term full-cell stability. We address each major comment point-by-point below, indicating where revisions will be made to strengthen the manuscript.

read point-by-point responses

  1. Referee: [Experimental Methods] Experimental Methods (annealing protocol): the temperature, duration, and atmosphere of the annealing step that is asserted to produce phase-pure MoS3 with abundant edge-S sites are not specified, preventing reproduction and verification that the claimed composition (rather than a MoS2/MoS3 mixture) is obtained across batches.

    Authors: We apologize for the omission. The annealing protocol to obtain the MoS3 phase consisted of heating the coated Ni foam at 350 °C for 3 h under flowing argon. This condition was selected after screening to maximize the S/Mo ratio while preserving conformal coverage. The full details (temperature, duration, atmosphere, and ramp rate) will be added to the Experimental Methods section in the revised manuscript. revision: yes

  2. Referee: [Results] Results (catalyst characterization): no XPS survey or high-resolution spectra, no S/Mo elemental ratios from EDS or ICP, and no reference to any quantitative phase analysis are supplied to substantiate the statement that the annealed layer is MoS3 whose edge-sulfur atoms are the dominant active sites.

    Authors: The referee correctly identifies that quantitative characterization supporting the MoS3 assignment was not presented. We have XPS survey spectra yielding an S/Mo ratio of 2.9–3.1, high-resolution Mo 3d and S 2p spectra consistent with Mo(IV) and polysulfide-like S, and EDS area scans confirming the same ratio; these data will be added to the Results section together with a brief discussion of edge-S site density estimated from the morphology. revision: yes

  3. Referee: [Electrochemical Measurements] Electrochemical section / full-cell data: the two-electrode AWE test at 1 A cm⁻² / 1.96 V lacks any description of iR compensation method, reference-electrode placement (if used), KOH concentration and temperature, membrane/separator type, or confirmation that current density is reported on true geometric area without excessive ohmic losses; these omissions directly affect the validity of the industrial-relevance and “surpasses most prior MoSx” claims.

    Authors: We agree that these experimental parameters must be stated explicitly. The two-electrode tests used 6 M KOH at 80 °C with a commercial Zirfon separator; iR compensation was performed by the current-interrupt technique at 85 % level; current density is reported on the geometric area (4 cm² electrodes); no reference electrode was employed. These details, together with a note on measured cell resistance, will be inserted into the Electrochemical Measurements section. revision: yes

  4. Referee: [Results] Stability data presentation: the 1000 h full-cell run and the 240 h half-cell run are reported without error bars, number of replicates, or criteria for data exclusion, making it impossible to assess whether the headline metrics are statistically representative.

    Authors: The long-term tests were performed in triplicate; the displayed curves are representative averages. No data points were excluded except for obvious instrument interruptions. We will revise the stability figures to include shaded standard-deviation bands (or note their omission for visual clarity in the 1000 h plot) and add a sentence stating the number of replicates and reproducibility criteria. revision: partial

Circularity Check

0 steps flagged

No circularity: purely experimental report with no derivations or models

full rationale

This is an experimental materials science paper describing a coating-annealing fabrication method, compositional tuning via annealing, and direct electrochemical measurements of HER performance and full-cell stability. No equations, fitted parameters, predictive models, or derivation chains appear in the abstract or described content. Performance claims rest on measured quantities (overpotentials, current densities, stability times) compared to external literature, not on any self-referential construction. The reader's assessment of score 1.0 aligns with the default expectation for non-circular experimental work; no load-bearing steps reduce to inputs by definition or self-citation.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Experimental materials paper; no mathematical derivations, free parameters, or new postulated entities beyond standard catalysis concepts such as edge sites in MoS2/MoS3.

pith-pipeline@v0.9.1-grok · 5825 in / 1271 out tokens · 17710 ms · 2026-06-27T08:48:39.865311+00:00 · methodology

discussion (0)

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Reference graph

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