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 CoS 2 fence layer on the external surface of highly active cobalt-doped MoS 2 , achieving a remarkable catalytic stability towards the alkaline hydrogen evolution reaction and improved activity. In situ spectroscopy uncovered the underlying molecular mechanism of the CoS 2 fence for breaking the activity-stability trade-off of the MoS 2 catalyst. This work offers valuable guidance for rationally designing efficient and stable NPM catalysts.