Atomically Ordered Pd-Zn Pair Sites Enable Electrochemistry-Assisted Dual Semi-Hydrogenation of Alkynols.

Electrochemical semi-hydrogenation (ECH) driven by renewable energy sources is a promising route for organic synthesis under ambient conditions, but conventional processes suffer from high energy consumption, poor selectivity, and limited Faradaic efficiency (FE). In this study, we report nanoporous PdZn with atomically ordered Pd-Zn pair sites (np-PdZn), synthesized via an electrochemical phase transformation approach, as an efficient catalyst for the electrocatalytic semi-hydrogenation of alkynols to alkenols. In situ spectroscopic studies and theoretical calculations reveal that the exceptional performance of np-PdZn originates from its atomically ordered Pd-Zn pair sites, wherein the Pd sites facilitate alkynol adsorption/activation while the Zn sites promote water adsorption/dissociation. The robust electronic interactions inherent to ordered Pd-Zn pair sites modulate the d-band center, promoting the dynamic regeneration of active sites through efficient desorption of alkenols, thereby suppressing undesired HER and over-hydrogenation. We further design an electrochemistry-assisted dual semi-hydrogenation system that combines the chemical and cathodic semi-hydrogenation of alkynols using np-PdZn as the electrocatalyst, which achieves concurrent electrochemical dual semi-hydrogenation of alkynols with a near-zero onset voltage, an FE approaching 200%, and an ultralow energy consumption of 0.19 kWh kg-1. This work establishes a new paradigm for designing atomically ordered pair-site catalysts and electrochemistry-assisted dual semi-hydrogenation systems for energy-efficient hydrogenation.