Industrial-level co-electrosynthesis of alkenol and Mg(OH)2 from seawater over Nd1Gd1 dual atomic site on metallene

Industrial-level alkynols electrocatalytic semi-hydrogenation using seawater as hydrogen source offers a sustainable alternative to conventional thermocatalytic routes, yet remains limited by the lack of efficient and robust electrocatalysts. Here, we report the synthesis of Nd₁Gd₁ dual atomic site on metallene for co-production of alkenol and magnesium hydroxide in the seawater system. Nd₁Gd₁Pd metallene achieves a selectivity of ≈96.7% and a Faradaic efficiency of ≈87.3% for the conversion of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol at -150 mA cm^-2 in a flow-cell system, and maintains ≈98.0% selectivity at 1.2 A for over 300 h of continuous operation, achieving the long-term stable co-electrosynthesis of alkenols and magnesium hydroxide in natural seawater at industrial-scale currents. Techno-economic analysis reveals a projected product revenue of at least $8,499 per ton of 2-methyl-3-buten-2-ol, underlining the industrial viability of this process. Mechanism investigations illustrate dual hydrogen-spillover and co-catalytic effects on Nd₁Gd₁Pd, promoting migration-reaction coupling mechanism of reactive *H to synergize hydrogenation. This work provides a seawater electrocatalytic semi-hydrogenation system and proposes an optimization strategy by atomically engineered dual hydrogen-spillover effect.