The Underlying Molecular Mechanism of Fence Engineering to Break the Activity–Stability Trade‐Off in Catalysts for the Hydrogen Evolution Reaction.

Non‐precious‐metal (NPM) catalysts often face the formidable challenge of a trade‐off between long‐term stability and high activity, which has not yet been widely addressed. Herein we propose a distinct molecule‐selective fence as a promising concept to solve this activity‐stability trade‐off. The fence encloses the catalyst and prevents species poisonous to the catalyst from reaching it, but allows catalytic reaction‐related species to diffuse freely. We constructed a CoS2 fence layer on the external surface of highly active cobalt‐doped MoS2, achieving a remarkable catalytic stability towards the alkaline hydrogen evolution reaction and improved activity. In situ spectroscopy uncovered the underlying molecular mechanism of the CoS2 fence for breaking the activity‐stability trade‐off of the MoS2 catalyst. This work offers valuable guidance for rationally designing efficient and stable NPM catalysts. [ABSTRACT FROM AUTHOR]