Electrocatalytic semi-hydrogenation of terminal alkynes through intermetallic hydrogen spillover on alloyed PdAu

Electrocatalytic semi-hydrogenation of alkynes offers a sustainable pathway for synthesizing functionalized olefins, yet challenges in achieving high selectivity and Faradaic efficiency at low overpotentials remain unresolved. Herein, we report bimetallic PdAu electrocatalysts (PdAu@CC) with low Pd loadings for selective semi-hydrogenation of terminal alkynes through an intermetallic hydrogen spillover pathway. The optimized PdAu@CC catalysts with a Pd molar fraction of 4 % demonstrate exceptional performance in converting acetylene benzene to vinyl benzene, achieving 97.5 % selectivity and 78.2 % Faradaic efficiency at a low potential of −0.17 V vs. RHE, outperforming monometallic Au@CC and Pd@CC. Mechanistic investigations reveal that highly dispersed Pd sites in the Au matrix efficiently dissociate water to generate active H* intermediates. Au sites activate alkynes and promote alkenes desorption, which effectively avoid over-hydrogenation of alkynes. Kinetically favorable Pd-to-Au hydrogen spillover enables selective alkynes-to-alkene hydrogenation, suppressing competitive hydrogen evolution. This work highlights the intermetallic hydrogen spillover as a strategic pathway for designing dual-active-site electrocatalysts with high performance in alkyne semi-hydrogenation.