Metal-support interaction triggered d-p orbital hybridization for efficient electrocatalytic semi-hydrogenation of alkynes

Semi-hydrogenation of alkynes to alkenes using electrochemical approaches is an appealing alternative to conventional thermocatalytic strategies, as it efficiently utilizes water as the hydrogen source at ambient temperature. However, the precise modulation of atomic and electronic structures of catalytic Pd active sites remains a persistent challenge, particularly in enhancing the conversion yield of alkynes and improving the selectivity of alkenes. Here, we synthesize Pd nanoparticles anchored onto the surface of the defective two-dimensional Fe₂O₃ support, referred to as Pd/Fe₂O₃ catalysts, to conduct the electrocatalytic semi-hydrogenation of alkynes. Intriguingly, we observed the reconstruction of the atomic structure and configuration of Pd nanoparticles in the Pd/Fe₂O₃ catalysts due to metal-support interaction, caused by the hybridization of Pd d and O p orbitals. This interaction significantly weakens the binding strength of Pd sites in the Pd/Fe₂O₃ catalysts to the chemisorbed 4-aminophenylacetylene and reactive hydrogen intermediates. Consequently, Pd/Fe₂O₃ catalysts achieve a high conversion rate (99%) and selectivity (99%) in the semi-hydrogenation of 4-aminophenylacetylene coupled with high faradaic efficiency, outperforming both benchmark commercial Pd/C and other reference catalysts. Additionally, terminal alkynes featuring diverse functionalized groups, including those with easily reducible or passivated functionalities, can be efficiently semi-hydrogenated using Pd/Fe₂O₃ catalysts.