Breaking the Energy Linear Relationships between C≡C and C═C Bonds over Porous Intermetallic Pd 2 Ga Metallene Boosting Alkynol Semihydrogenation

The electrochemical semihydrogenation (ECSH) of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE), using water as a hydrogen source, offers a sustainable pathway for chemical synthesis. However, conventional Pd-based catalysts are limited by the linear scaling relationships (LSRs) between the adsorption energies of C≡C and C═C bonds, often leading to overhydrogenation into 2-methyl-3-butan-2-ol (MBA) and, thus, reduced selectivity toward MBE. In this work, we report a solvothermal approach for synthesizing porous intermetallic Pd₂Ga (PI-Pd₂Ga) metallene as a high-performance catalyst for the ECSH of MBY to MBE. The PI-Pd₂Ga metallene exhibits an optimized electronic structure and an expanded Pd interatomic distance (d_Pd-Pd), which facilitates MBY adsorption, H₂O dissociation, and MBE* desorption. These distinctive structural properties effectively break the LSRs between C≡C and C═C bonds, resulting in a high MBE selectivity of 96.99%, an MBE Faradaic efficiency (FE_MBE) of 92.85%, excellent stability, and broad substrate applicability. This work provides a strategy for the rational design and development of efficient catalysts for selective semihydrogenation reactions.