Allotrope-dependent activity-stability relationships of molybdenum sulfide hydrogen evolution electrocatalysts
MoS₂ HER stability is allotrope-dependent: lamellar MoS₂ degrades under open circuit conditions, while amorphous MoS₃ₓ loses sulfur during HER, generating undercoordinated Mo sites. Simultaneous ICP-MS and EC-MS monitoring of dissolution products underpins revised stability metrics and a proposed HER mechanism accounting for both Mo and S dissolution pathways.