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arxiv: 2604.04718 · v1 · submitted 2026-04-06 · ❄️ cond-mat.mtrl-sci

Transforming Discarded Thermoelectrics into High-Performance HER Catalysts

Gemeda Jemal Usa , Caique C. Oliveira , Varinder Pal , Suman Sarkar , Gebisa Bekele Feyisa , Moumita Kotal , Emmanuel Femiolu , Pedro A. S. Autreto
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Temesgen Debelo Desissa Chandra Sekhar Tiwary
This is my paper

Pith reviewed 2026-05-10 19:53 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords thermoelectric wasteHER catalystheterostructurehydrogen evolutionelectrocatalystrecyclingBiSbTe3/ZnTecircular economy
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The pith

Melting thermoelectric waste produces a BiSbTe3/ZnTe heterostructure that serves as an effective hydrogen evolution catalyst.

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

The paper establishes that discarded thermoelectric materials can be repurposed as electrocatalysts for the hydrogen evolution reaction through melting-casting processing that forms a BiSbTe3/ZnTe heterostructure. This route yields lower overpotential, a smaller Tafel slope, and multi-hour stability compared to ball-milled waste containing a different heterostructure, directly tying e-waste recycling to clean hydrogen production. The gains arise from accelerated charge transfer, faster water dissociation, and rapid hydrogen adsorption at defect-rich interfaces. Computational modeling confirms that the heterostructure strengthens bonding states near the Fermi level to support the reaction. A reader would see this as a practical link between waste management and scalable, low-carbon catalyst synthesis.

Core claim

The paper claims that melting-cast thermoelectric waste forms a BiSbTe3/ZnTe heterostructure with defect-enriched interfaces, which produces superior HER performance through accelerated charge transfer, fast water dissociation, and rapid hydrogen adsorption. This delivers an overpotential of 641 mV at 10 mA/cm², a Tafel slope of 233 mV/dec, and stable operation for 5.5 hours with negligible current decay, outperforming ball-milled waste that contains a Bi2Te3/BiSbTe3 heterostructure. DFT calculations show the BiSbTe3/ZnTe interface strengthens bonding states near the Fermi level, thereby enhancing activity.

What carries the argument

The BiSbTe3/ZnTe heterostructure with defect-enriched interfaces, which forms during melting casting and improves electronic states and reaction kinetics for hydrogen evolution.

Load-bearing premise

The performance difference between the two processed samples stems from the specific BiSbTe3/ZnTe heterostructure and defects rather than uncontrolled variations in surface area, impurities, or morphology.

What would settle it

Preparing a ball-milled sample with matched surface area and composition that lacks the ZnTe component yet achieves equal or better overpotential, Tafel slope, and stability would show the heterostructure is not the decisive factor.

read the original abstract

With the increase in the complexity of the materials used in various sophisticated electronic devices, recycling of E-waste is becoming challenging. In the present study, we have converted thermoelectric (TE) waste into functional HER electrocatalyst by considering circular-economy and low-carbon approach. The as received TE waste was processed through ball milling (TE waste-BM) and melting casting (TE waste-M) routes. Morphological and structural evaluations revealed that the formation of BiSbTe3/ZnTe heterostructure in TE-waste-M promote HE efficiency when compared to the presence of Bi2Te3/BiSbTe3 heterostructure (TE-waste-BM). TE waste-M exhibited lower overpotential (641 mV at 10 mA/sq.cm), smaller Tafel slope (233 mV/dec) and stable operation for 5.5 h with negligible current decay than that of TE waste-BM, attributed to the accelerated charge transfer, fast water dissociation steps and rapid hydrogen adsorption in TE waste-M, originated from the presence of BiSbTe3/ZnTe heterostructure, defect enriched interfaces. Density functional theory calculations supported the experimental findings, revealing that heterostructures strengthens the bonding states near the Fermi level, thereby enhancing the HER activity of BiSbTe3/ZnTe heterostructure. This work simultaneously integrates waste management with green hydrogen production by offering an economically viable, scalable and low-carbon approach for HER catalysts.

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 paper claims that thermoelectric (TE) waste can be repurposed as HER electrocatalysts via two routes: ball milling (TE waste-BM, forming Bi2Te3/BiSbTe3 heterostructure) and melting-casting (TE waste-M, forming BiSbTe3/ZnTe heterostructure). TE waste-M shows superior performance with an overpotential of 641 mV at 10 mA/cm², Tafel slope of 233 mV/dec, and 5.5 h stability, attributed to accelerated charge transfer and hydrogen adsorption from the heterostructure and defects; this is supported by DFT calculations showing strengthened bonding states near the Fermi level.

Significance. If the performance advantage is causally linked to the specific BiSbTe3/ZnTe heterostructure rather than uncontrolled morphological factors, the work provides a scalable, low-carbon route to recycle complex E-waste into functional catalysts for green hydrogen, advancing circular-economy principles. The experimental-DFT integration is a strength, but the modest metrics (high overpotential relative to benchmarks) limit immediate impact on HER technology.

major comments (2)
  1. [Abstract and Results/Discussion] The central attribution of lower overpotential (641 mV at 10 mA/cm²) and Tafel slope (233 mV/dec) in TE waste-M to the BiSbTe3/ZnTe heterostructure and defect-enriched interfaces (Abstract; Results/Discussion) is not isolated from processing effects. No BET surface area, ECSA normalization of currents, or controls for particle size/porosity differences between melt-cast and ball-milled samples are reported, leaving open that gains arise from higher accessible area or morphology changes rather than the interface itself.
  2. [Abstract and Electrochemical Measurements] The 'high-performance' framing is undermined by the reported metrics: 641 mV overpotential at 10 mA/cm² is modest, with no error bars, replicate data, or baseline comparisons to commercial Pt/C or state-of-the-art HER catalysts provided in the electrochemical characterization.
minor comments (2)
  1. [Abstract] Standardize units: '10 mA/sq.cm' should read '10 mA cm⁻²' throughout.
  2. [Abstract] Clarify 'HE efficiency' as 'HER efficiency' for precision.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback on our manuscript. We address each major comment below, providing clarifications and committing to revisions that strengthen the isolation of the heterostructure effect and contextualize the performance metrics within the circular-economy focus of the work.

read point-by-point responses

  1. Referee: [Abstract and Results/Discussion] The central attribution of lower overpotential (641 mV at 10 mA/cm²) and Tafel slope (233 mV/dec) in TE waste-M to the BiSbTe3/ZnTe heterostructure and defect-enriched interfaces (Abstract; Results/Discussion) is not isolated from processing effects. No BET surface area, ECSA normalization of currents, or controls for particle size/porosity differences between melt-cast and ball-milled samples are reported, leaving open that gains arise from higher accessible area or morphology changes rather than the interface itself.

    Authors: We agree that additional controls are needed to isolate the contribution of the BiSbTe3/ZnTe heterostructure from morphological differences. In the revised manuscript, we will add BET surface area measurements for both TE waste-BM and TE waste-M samples, perform double-layer capacitance measurements to determine ECSA, and normalize all HER currents to ECSA. We will also include quantitative particle size distributions from SEM/TEM images and discuss porosity effects to rule out accessible-area contributions. These additions will allow us to more rigorously attribute the performance difference to the heterostructure and defect-enriched interfaces as supported by the DFT results. revision: yes

  2. Referee: [Abstract and Electrochemical Measurements] The 'high-performance' framing is undermined by the reported metrics: 641 mV overpotential at 10 mA/cm² is modest, with no error bars, replicate data, or baseline comparisons to commercial Pt/C or state-of-the-art HER catalysts provided in the electrochemical characterization.

    Authors: We acknowledge that 641 mV overpotential at 10 mA/cm² is modest compared to Pt/C and does not represent state-of-the-art HER performance. The manuscript's emphasis is on sustainable recycling of thermoelectric waste rather than achieving benchmark metrics. In revision, we will add error bars from at least three replicate measurements, include direct LSV comparisons to commercial Pt/C under identical conditions, and moderate language in the abstract and discussion to highlight the circular-economy advantages instead of using 'high-performance' without qualification. We will also contextualize the results against other waste-derived non-precious catalysts. revision: yes

Circularity Check

0 steps flagged

No circularity in experimental and DFT-supported claims

full rationale

The paper's derivation rests on direct experimental processing (ball-milling vs. melt-casting of TE waste), structural characterization identifying distinct heterostructures (Bi2Te3/BiSbTe3 vs. BiSbTe3/ZnTe), electrochemical HER metrics, and separate DFT calculations on bonding states near the Fermi level. No self-definitional loops, fitted inputs renamed as predictions, load-bearing self-citations, or ansatzes smuggled via prior work appear in the chain. The central attribution of performance gains to the heterostructure and defects follows from observed differences and independent computation, remaining self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The claim depends on experimental processing outcomes and DFT electronic-structure calculations; no explicit free parameters, new physical entities, or non-standard axioms are introduced in the abstract.

pith-pipeline@v0.9.0 · 5609 in / 1333 out tokens · 79075 ms · 2026-05-10T19:53:32.118454+00:00 · methodology

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Reference graph

Works this paper leans on

4 extracted references · 4 canonical work pages

  1. [1]

    1 R. Seif, F. Z. Salem and N. K. Allam, E-waste recycled materials as efficient catalysts for renewable energy technologies and better environmental sustainability, Environ. Dev. Sustain., 2024, 26, 5473–5508. 2 S. Mathi, H. Akhdar, R. S. Shetti, T. Alinad, A. N. Alodhayb, K. Mondal and N. P. Shetti, Amorphous electrocatalysts for oxygen and hydrogen evol...

    work page doi:10.1002/smll.202509283 2024

  2. [2]

    8 I. Rey, V. L. Barrio and I. Agirre, Environmental assessment of a hydrogen supply chain using LOHC system with novel low-PGM catalysts: A life cycle approach, Int. J. Hydrogen Energy, 2025, 142, 616–626. 9 W. Cai, S. Ito, E. Morioka, C. Chuaicham, A. Ulmaszoda, H. Miki and K. Sasaki, Synthesis of TiO2/copper-based oxide photocatalytic composites from co...

    work page doi:10.1063/1.3382344 2025

  3. [3]

    32 Q. Hua, X. Chen, J. Chen, N. M. Alghoraibi, Y. Lee, T. J. Woods, R. T. Haasch, S. C. Zimmerman and A. A. Gewirth, Inducing Microstrain in Electrodeposited Pt through Polymer Addition for Highly Active Oxygen Reduction Catalysis, ACS Catal., 2024, 14, 7526–7535. 33 E. Westsson, S. Picken and G. Koper, The effect of lattice strain on catalytic activity, ...

    work page 2024

  4. [4]

    Jilani, J

    37 A. Jilani, J. Iqbal, M. S. Abdel-Wahab, Y. Jamil and A. A. Al-Ghamdi, X-ray photoelectron spectroscopic (XPS) investigation of interface diffusion of ZnO/Cu/ZnO multilayer, J. Optoelectron. Biomed. Mater., 2016, 8, 27–31. 38 M. A. Qadeer, X. Zhang, M. A. Farid, M. Tanveer, Y. Yan, S. Du, Z.-F. Huang, M. Tahir and J.-J. Zou, A review on fundamentals for...

    work page 2016