Hydrogen Spillover Mediated Synergy of Cobalt Dual‐Sites for Breaking the Activity‐Selectivity Trade‐Off in Electrocatalytic Alkynol Semi‐Hydrogenation

Simultaneously achieving high activity, selectivity, and Faradaic efficiency for electrocatalytic alkyne semi‐hydrogenation remains a formidable challenge due to competing hydrogen evolution and over‐hydrogenation. Despite atomically dispersed metals delivering high performance for hydrogenation of unsaturated compounds, their structural simplicity fundamentally limits their ability for electrocatalytic alkyne semi‐hydrogenation, which involves cascade steps of water activation for H* generation and alkyne activation for hydrogenation. Herein, we designed a dual‐site catalyst comprising cobalt single atoms and nanoparticles co‐anchored on N‐doped carbon for semi‐hydrogenation of alkynol through the hydrogen spillover pathway. Theoretical calculations reveal cobalt nanoparticles as active sites for water dissociation and H * generation. Meanwhile, the H * species spilled over via the Grotthuss mechanism, selectively hydrogenates alkynols on cobalt single atoms through an Eley–Rideal mechanism, thereby kinetically facilitating alkynols' semi‐hydrogenation. Extensive experiments and theoretical calculations demonstrated that hydrogen spillover of H * species from nanoparticles to single atoms balanced H * supply/consumption, effectively suppressing hydrogen generation and over‐hydrogenation. Using 2‐methyl‐3‐butyne‐2‐ol as the substrate, dual‐site electrocatalyst delivered an excellent 2‐methyl‐3‐butene‐2‐ol production rate of 2.38 mmol cm −2 h −1 with 95.2% Faradaic efficiency and >99% selectivity. Additionally, the electrocatalyst exhibited remarkable stability and promising economic feasibility in a flow cell system, highlighting its potential for practical applications.