Active Hydrogen Reservoir Enabled by p-d Orbital Hybridization in PdSb Metallene for Electrocatalytic Alkynol Semi‑Hydrogenation at Large Current Densities.

Abstract

Electrocatalytic semi-hydrogenation reaction (ESHR) represents a promising sustainable production route, making the electrocatalytic synthesis of alkenol from alkynol at near-industrial current densities particularly significant. However, large current densities readily promote the competing hydrogen evolution reaction (HER), which consequently reduces the overall reaction efficiency. Here, we report a PdSb metallene (PdSb ene) electrocatalyst that overcomes this limitation by functioning as an efficient "active hydrogen reservoir". The p-d orbital hybridization induced by Sb incorporation modulates the electronic structure of Pd, which facilitates water dissociation, stabilizes H* intermediates, and steers the hydrogenation pathway toward thermodynamic favorability. Operating at a current density of -200 mA cm^-2, the PdSb ene catalyst achieved the semi-hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) with a 92% conversion, 96% selectivity, and 88% Faradaic efficiency, while maintaining stable performance for over 400 h. This work demonstrates that constructing an orbital‑hybridization‑driven "active hydrogen reservoir" is a viable strategy for efficient electrosynthesis under demanding conditions.