Defect-Driven Catalysis and Phase Relaxation in MoS2 Nanoflower-Derived Nanosheets during Hydrogen Evolution

Abstract

Engineering the electronic structure of molybdenum disulfide (MoS2) through phase composition and intrinsic defect chemistry offers a promising strategy to overcome its limited hydrogen evolution reaction (HER) activity in acidic media. Herein, we report a phase-relaxation-assisted mechanism in delaminated MoS2 nanoflower-derived nanosheets, where controlled cathodic biasing induces a partial transformation from the metallic 1T phase to the semiconducting 2H phase while the intrinsic structural defects present in the as-synthesized material are preserved. Under HER conditions, surface oxidation (formation of S–Ox species) increases, yet the overall S/Mo stoichiometry remains unchanged. The synergistic features enable efficient charge transfer and deliver an overpotential of 198 mV at 10 mA cm–2, a Tafel slope of 87 mV dec–1, and a hydrogen production rate of ∼11.2 mol g–1 at 50 mA cm–2. In situ electron paramagnetic resonance, combined with ex situ Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, confirm the initial 1T-rich character, the progressive 1T → 2H relaxation under HER conditions, and the persistence of defect-enriched regions alongside surface oxidation. These findings highlight the subtle activation–deactivation interplay in MoS2 catalysts and underscore the importance of phase stability and intrinsic defect control for durable, high-performance HER MoS2-based electrocatalysis.

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Cite

BibTeX RIS

BibTeX

@article{wenelska2026defectdriven,
  title = {{Defect-Driven Catalysis and Phase Relaxation in MoS2 Nanoflower-Derived Nanosheets during Hydrogen Evolution}},
  author = {Karolina Wenelska and Grzegorz Leniec and Veronica Montes-García and Tomasz Chudziak and Martijn De Feyter and Bowen Zhang and Xiaoguang Liu and Artur Ciesielski and Ewa Mijowska},
  journal = {Chemistry of Materials},
  year = {2026},
  month = aug,
  doi = {10.1021/acs.chemmater.6c01450},
  url = {https://univoak.hal.science/hal-05759867v1},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - Defect-Driven Catalysis and Phase Relaxation in MoS2 Nanoflower-Derived Nanosheets during Hydrogen Evolution
AU  - Karolina Wenelska
AU  - Grzegorz Leniec
AU  - Veronica Montes-García
AU  - Tomasz Chudziak
AU  - Martijn De Feyter
AU  - Bowen Zhang
AU  - Xiaoguang Liu
AU  - Artur Ciesielski
AU  - Ewa Mijowska
PY  - 2026
DA  - 2026/08/31
JO  - Chemistry of Materials
DO  - 10.1021/acs.chemmater.6c01450
UR  - https://univoak.hal.science/hal-05759867v1
AB  - Engineering the electronic structure of molybdenum disulfide (MoS2) through phase composition and intrinsic defect chemistry offers a promising strategy to overcome its limited hydrogen evolution reaction (HER) activity in acidic media. Herein, we report a phase-relaxation-assisted mechanism in delaminated MoS2 nanoflower-derived nanosheets, where controlled cathodic biasing induces a partial transformation from the metallic 1T phase to the semiconducting 2H phase while the intrinsic structural defects present in the as-synthesized material are preserved. Under HER conditions, surface oxidation (formation of S–Ox species) increases, yet the overall S/Mo stoichiometry remains unchanged. The synergistic features enable efficient charge transfer and deliver an overpotential of 198 mV at 10 mA cm–2, a Tafel slope of 87 mV dec–1, and a hydrogen production rate of ∼11.2 mol g–1 at 50 mA cm–2. In situ electron paramagnetic resonance, combined with ex situ Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, confirm the initial 1T-rich character, the progressive 1T → 2H relaxation under HER conditions, and the persistence of defect-enriched regions alongside surface oxidation. These findings highlight the subtle activation–deactivation interplay in MoS2 catalysts and underscore the importance of phase stability and intrinsic defect control for durable, high-performance HER MoS2-based electrocatalysis.
SN  - 0897-4756
SN  - 1520-5002
ER  -

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