arxiv: 2605.06348 · v1 · submitted 2026-05-07 · ❄️ cond-mat.mtrl-sci

Recognition: unknown

From Deposition Stress to Surface Reactivity: Strain-Dependent Hydrogen Evolution on Sputtered Platinum Thin Films

Sabrina Baha , Alejandro E. Perez Mendoza , Leonardo H. Morais , Aleksander Kostka , Shivam Shukla , Ellen Suhr , Andre Oliveira , Annika Gatzki

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Henrik H. Kristoffersen Jan Rossmeisl Corina Andronescu Alfred Ludwig

Authors on Pith no claims yet

Pith reviewed 2026-05-08 08:44 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci

keywords platinum thin filmshydrogen evolution reactionmagnetron sputteringlattice strainelectrocatalysisdensity functional theorysurface adsorptionthin film microstructure

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The pith

Residual lattice strain in sputtered platinum films controls hydrogen evolution activity more than surface area.

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

The paper shows that platinum thin films made by magnetron sputtering at low pressure give the highest rates for the hydrogen evolution reaction, while films made at high pressure give lower rates even though they are rougher and have more surface area. The authors trace the difference to residual lattice strain left in the films by the deposition process. Density functional theory calculations on the Pt(111) surface indicate that this strain shifts the energy of hydrogen adsorption and changes how much hydrogen covers the surface at operating conditions. A reader would care because the result suggests that simple changes in how the film is grown can improve catalytic performance without adding more platinum or redesigning the electrode geometry.

Core claim

Magnetron-sputtered platinum thin films change from dense and smooth to porous and rough as sputter pressure is raised. Electrochemical tests show that the low-pressure films deliver the highest HER activity while high-pressure films lose activity despite greater roughness. DFT calculations on strained Pt(111) surfaces demonstrate that lattice strain modifies hydrogen adsorption free energies and equilibrium surface coverages, supplying a direct link to the measured activity trends. The overall finding is that residual strain, microstructure, and hydrogen coverage together set the reactivity of these sputtered films.

What carries the argument

Residual lattice strain within (111)-textured platinum films, which shifts hydrogen adsorption energetics and surface coverage according to DFT calculations.

Load-bearing premise

The claim assumes that residual strain effects on hydrogen adsorption are the main reason activity differs, rather than other sputter-pressure effects such as impurity levels or defect populations.

What would settle it

Prepare Pt films on lattice-mismatched substrates that impose a chosen strain level independent of sputtering pressure, then measure whether HER activity tracks the imposed strain value rather than the measured roughness or porosity.

read the original abstract

Strain has emerged as a promising approach for tuning electrocatalytic properties, yet its role in sputter-deposited thin films remains poorly understood. In this work, magnetron-sputtered platinum (Pt) thin films with different stress states were prepared by varying the sputter pressure. The resulting changes in microstructure, residual strain, and hydrogen evolution reaction (HER) activity were investigated using complementary characterization techniques and density functional theory (DFT) calculations. Structural analysis reveals a transition of (111)-textured Pt thin films from dense and smooth films at low pressures, to more porous microstructures with increased roughness at higher pressures. Electrochemical measurements show that films deposited at low sputter pressure exhibit the highest HER activity, while higher sputter pressures lead to reduced activity despite increased surface area. DFT calculations demonstrate that lattice strain alters hydrogen adsorption energetics and surface coverage on Pt(111), providing a mechanistic explanation for the observed activity trends. Overall, the results highlight that HER activity in sputtered Pt thin films is governed by the interplay of residual strain, microstructure, and hydrogen coverage.

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.

Desk Editor's Note private letter to a colleague

The paper shows low-pressure sputtered Pt films give higher HER activity despite lower area, with DFT linking it to strain-altered H coverage, but microstructure shifts from the same pressure change are not isolated.

read the letter

The core observation is that Pt films deposited at low sputter pressure are dense and smooth with the best HER performance on geometric area, while higher pressures produce rougher, more porous films whose activity drops even though surface area rises. The DFT calculations on strained Pt(111) show how compressive strain can shift hydrogen adsorption energies and coverage in a way that matches the trend. That combination of deposition control, structural data, and theory is the main new piece here. They do a clean job of mapping the pressure series to XRD peak shifts for strain, SEM/AFM for morphology, and standard electrochemical tests, then using off-the-shelf adsorption calculations to close the loop. The story is coherent and the activity difference is reported independently of the modeling. The limitation is that sputter pressure changes both strain and microstructure at once. The porous films at higher pressure likely add grain boundaries, undercoordinated sites, or possible impurities that can change HER rates on their own. The DFT only treats uniform biaxial strain on perfect terraces, so it does not test whether those defect effects dominate. No control run, such as mild annealing to relax strain at fixed morphology or epitaxial growth at constant pressure, is described to separate the two. The central claim therefore rests on correlation plus a plausible but incomplete mechanistic model. Readers working on sputtered thin-film catalysts for HER will find the experimental trends and deposition knob useful. The work is grounded enough in data and standard methods to merit referee time, even if revisions will probably be needed to address the decoupling issue and add error bars or statistical checks on the electrochemistry.

Referee Report

1 major / 3 minor

Summary. The manuscript examines magnetron-sputtered Pt thin films prepared at different sputter pressures, using XRD to track residual strain, SEM/AFM to characterize microstructure and roughness, and electrochemical measurements to assess HER activity. It reports highest HER activity for low-pressure dense films despite lower surface area, reduced activity at higher pressures despite increased roughness/porosity, and employs DFT on strained Pt(111) to link biaxial strain to altered H adsorption energetics and coverage, concluding that activity arises from the interplay of strain, microstructure, and hydrogen coverage.

Significance. If the strain contribution can be isolated from microstructural confounders, the work would provide a concrete demonstration of deposition-parameter control over electrocatalytic activity in thin-film Pt, with implications for scalable catalyst fabrication. The multi-technique experimental suite combined with standard DFT adsorption calculations on (111) surfaces constitutes a strength, though the absence of reported error bars and statistical controls limits immediate verifiability.

major comments (1)

[Results/Discussion (structural, electrochemical, and DFT sections)] The central mechanistic claim—that residual lattice strain (via XRD peak shifts) primarily governs the HER activity trends through modified H adsorption—is load-bearing yet not isolated from microstructure. Sputter pressure simultaneously relaxes strain and induces a transition to porous/rough films (SEM/AFM), so the observed activity drop at high pressure could arise from defect sites, grain boundaries, or impurity effects rather than uniform biaxial strain on ideal terraces. No control experiment (e.g., mild annealing to relax strain at fixed microstructure or epitaxial growth at constant pressure) is described to decouple these variables, and DFT addresses only ideal Pt(111) without modeling undercoordinated or defect-rich surfaces.

minor comments (3)

[Electrochemical measurements] Electrochemical data lack reported error bars, replicate statistics, or explicit exclusion criteria for outliers, reducing the ability to assess the significance of activity differences between pressure conditions.
[Electrochemical measurements] Clarify whether reported currents are normalized to geometric area only or to ECSA, and specify the method used for ECSA determination (e.g., H adsorption charge or impedance).
[DFT calculations] In the DFT section, explicitly map the strain values employed in the calculations to the experimental lattice parameters extracted from XRD, and discuss the range of validity for the biaxial strain model.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive feedback and for recognizing the multi-technique experimental suite. Below we respond point-by-point to the major comment, clarifying the evidence for strain effects while acknowledging the coupled influence of microstructure.

read point-by-point responses

Referee: The central mechanistic claim—that residual lattice strain (via XRD peak shifts) primarily governs the HER activity trends through modified H adsorption—is load-bearing yet not isolated from microstructure. Sputter pressure simultaneously relaxes strain and induces a transition to porous/rough films (SEM/AFM), so the observed activity drop at high pressure could arise from defect sites, grain boundaries, or impurity effects rather than uniform biaxial strain on ideal terraces. No control experiment (e.g., mild annealing to relax strain at fixed microstructure or epitaxial growth at constant pressure) is described to decouple these variables, and DFT addresses only ideal Pt(111) without modeling undercoordinated or defect-rich surfaces.

Authors: We agree that sputter pressure simultaneously modulates residual strain and microstructure, as shown by the XRD peak shifts, SEM/AFM roughness/porosity data, and the transition from dense to porous films. However, the electrochemical results demonstrate that HER activity is highest for the low-pressure, strained, dense films and decreases at higher pressures despite the increase in surface area and roughness. This inverse correlation with roughness indicates that the loss of compressive strain (which DFT shows optimizes H adsorption energy and coverage on Pt(111)) outweighs any microstructural gains. The manuscript abstract and discussion already frame the activity as arising from the interplay of strain, microstructure, and hydrogen coverage rather than strain as the sole factor. While dedicated control experiments such as post-deposition annealing at fixed microstructure or epitaxial growth would strengthen isolation of variables, these lie outside the present scope. The (111) texture of all films justifies the use of strained Pt(111) models in DFT; extending to defect-rich surfaces would require separate, more computationally intensive studies. We will add explicit discussion of these limitations and the correlative nature of the evidence. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation chain is self-contained

full rationale

The paper reports independent experimental trends in HER activity versus sputter pressure (with accompanying XRD/SEM/AFM characterization of strain and microstructure) and performs separate standard DFT adsorption calculations on biaxially strained Pt(111). No equation or claim reduces a fitted parameter to a renamed prediction, no self-citation supplies a load-bearing uniqueness theorem, and the DFT step uses unmodified first-principles energetics without ansatz smuggling or self-definition. The mechanistic link is an external interpretation rather than a closed loop.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard materials-science and computational assumptions without introducing new fitted parameters or postulated entities.

axioms (1)

standard math Standard DFT approximations (exchange-correlation functional, slab model) accurately capture hydrogen adsorption energetics on strained Pt(111)
Invoked to link lattice strain to adsorption energy and coverage changes.

pith-pipeline@v0.9.0 · 5541 in / 1363 out tokens · 73579 ms · 2026-05-08T08:44:00.916749+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

4 extracted references · 3 canonical work pages

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Perez Mendoza2, Leonardo H

1 From Deposition Stress to Surface Reactivity: Strain-Dependent Hydrogen Evolution on Sputtered Platinum Thin Films Sabrina Baha1, Alejandro E. Perez Mendoza2, Leonardo H. Morais1, Aleksander Kostka3, Shivam Shukla2, Ellen Suhr1, Andre Oliveira2†, Annika Gatzki1, Henrik H. Kristoffersen4, Jan Rossmeisl4, Corina Andronescu2*, Alfred Ludwig1,3* 1 Material ...

1929
[2]

Strain-induced perturbations in G⁰(θ) therefore are captured in the D1 and D2 desorption features

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work page doi:10.5281/zenodo.19705685 2021
[3]

S.; Nygaard, M

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[4]

A.; Hjörvarsson, B

DOI: 10.1038/s41467-022-30241-7 (63) Umezawa, K.; Ito, T.; Asada, M.; Nakanishi, S.; Ding, P.; Lanford, W. A.; Hjörvarsson, B. Adsorption of hydrogen on the Pt(111) surface from low-energy recoil scattering. Surface Science 1997, 387 (1–3), 320–327. DOI: 10.1016/s0039-6028(97)00367-1 (64) Zolfaghari, A.; Jerkiewicz, G. Temperature-dependent research on Pt...

work page doi:10.1038/s41467-022-30241-7 1997