Allotrope-dependent activity-stability relationships of molybdenum sulfide hydrogen evolution electrocatalysts

Allotrope-dependent activity-stability relationships of molybdenum sulfide hydrogen evolution electrocatalysts

WoS Article

Molybdenum disulfide (MoS2) is widely regarded as a competitive hydrogen evolution reaction (HER) catalyst to replace platinum in proton exchange membrane water electrolysers (PEMWEs). Despite the extensive knowledge of its HER activity, stability insights under HER operation are scarce. This is paramount to ensure long-term operation of Pt-free PEMWEs, and gain full understanding on the electrocatalytically-induced processes responsible for HER active site generation. The latter are highly dependent on the MoS2 allotropic phase, and still under debate. We rigorously assess these by simultaneously monitoring Mo and S dissolution products using a dedicated scanning flow cell coupled with downstream analytics (ICP-MS), besides an electrochemical mass spectrometry setup for volatile species analysis. We observe that MoS2 stability is allotrope-dependent: lamellar-like MoS2 is highly unstable under open circuit conditions, whereas cluster-like amorphous MoS3-x instability is induced by a severe S loss during the HER and undercoordinated Mo site generation. Guidelines to operate non-noble PEMWEs are therefore provided based on the stability number metrics, and an HER mechanism which accounts for Mo and S dissolution pathways is proposed. The stability of non-noble catalysts is key for their use in proton exchange membrane water electrolysers. Here, authors study activity-stability relationships of MoSx allotropes for H2 production, reporting allotrope-dependent stabilities and dissolution pathways, and propose operation guidelines.

Molybdenum disulfide (MoS2) is widely regarded as a competitive hydrogen evolution reaction (HER) catalyst to replace platinum in proton exchange membrane water electrolysers (PEMWEs). Despite the extensive knowledge of its HER activity, stability insights under HER operation are scarce. This is paramount to ensure long-term operation of Pt-free PEMWEs, and gain full understanding on the electrocatalytically-induced processes responsible for HER active site generation. The latter are highly dependent on the MoS2 allotropic phase, and still under debate. We rigorously assess these by simultaneously monitoring Mo and S dissolution products using a dedicated scanning flow cell coupled with downstream analytics (ICP-MS), besides an electrochemical mass spectrometry setup for volatile species analysis. We observe that MoS2 stability is allotrope-dependent: lamellar-like MoS2 is highly unstable under open circuit conditions, whereas cluster-like amorphous MoS3-x instability is induced by a severe S loss during the HER and undercoordinated Mo site generation. Guidelines to operate non-noble PEMWEs are therefore provided based on the stability number metrics, and an HER mechanism which accounts for Mo and S dissolution pathways is proposed. The stability of non-noble catalysts is key for their use in proton exchange membrane water electrolysers. Here, authors study activity-stability relationships of MoSx allotropes for H2 production, reporting allotrope-dependent stabilities and dissolution pathways, and propose operation guidelines.

CATALYTIC-ACTIVITY; EVOLVING CATALYST; PHASE-TRANSITION; SULFUR VACANCIES; NATURAL CRYSTALS; EDGE SITES; MOS2; IDENTIFICATION; MONOLAYER; SPECTROSCOPY

CATALYTIC-ACTIVITY; EVOLVING CATALYST; PHASE-TRANSITION; SULFUR VACANCIES; NATURAL CRYSTALS; EDGE SITES; MOS2; IDENTIFICATION; MONOLAYER; SPECTROSCOPY

ESCALERA-LÓPEZ, D.; IFFELSBERGER, C.; ZLATAR, M.; NOVČIĆ, K.; MASELJ, N.; VAN PHAM, C.; JOVANOVIČ, P.; HODNIK, N.; THIELE, S.; PUMERA, M.; CHEREVKO, S.

2025

29.04.2024

NATURE PORTFOLIO

BERLIN

2041-1723

Nature Communications

15

1

United Kingdom of Great Britain and Northern Ireland

1

13

13

https://www.nature.com/articles/s41467-024-47524-w

http://hdl.handle.net/11012/252863

s41467-024-47524-w