Interstitial-Carbon-Triggered p-d-p Orbital Hybridization in Pd<sub>3</sub>BiC<sub><i>x</i></sub> Metallene for Electrocatalytic Alkynol Semi-Hydrogenation.

Sun, Kuo; Xiao, Ningxin; Jiang, Shaojian; Deng, Kai; Xu, You; Wang, Ziqiang; Wang, Liang; Yu, Hongjie et al. · ACS Nano · 2026

basic_science · Level V

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Abstract

Electrocatalytic alkynol semihydrogenation (EASH) represents a promising alternative to conventional alkenol production. However, it is plagued by severe overhydrogenation and a competitive hydrogen evolution reaction (HER). In this work, we synthesize a Pd<sub>3</sub>BiC<sub>x</sub> intermetallic carbide metallene (Pd<sub>3</sub>BiC<sub>x</sub> ene) as a high-performance electrocatalyst for the selective semihydrogenation of 2-methyl-3-butyn-2-ol (MBY). At -0.3 V vs RHE, the catalyst system achieves 94.1% conversion, 95.3% selectivity, and 90.4% Faradaic efficiency while maintaining long-term stability over 70 h. Mechanistic studies demonstrate that carbon doping induces synergistic p-d-p orbital hybridization among Pd, Bi, and C. This electronic structure modulation optimizes the adsorption energy of MBY while facilitating the desorption of 2-methyl-3-buten-2-ol (MBE). Furthermore, carbon doping kinetically hinders overhydrogenation by eliminating subsurface hydrogen species and increasing the energy barrier for the overhydrogenation step. Concurrently, this p-d-p hybridization stabilizes surface adsorbed hydrogen (H*<sub>ads</sub>), thereby promoting the hydrogenation pathway and suppressing the HER. This work establishes an effective catalyst design strategy for fabricating p-d-p orbital-hybridized intermetallic catalysts, offering an innovative approach for high-efficiency EASH.