Weak interfacial energy for magnesium salt-resistant ampere-level hydrogen production from natural seawater

Abstract Hydrogen production from natural seawater is currently one of the important approaches to solve the problem of industrial hydrogen production that relies on freshwater resources. However, the deposition of Mg(OH)2 on the cathode surface at high current densities severely hinders its practical development. Herein, we loaded oxygen vacancy (Ov)-rich NiO@MoO2 (NMO) nanosheet catalysts onto the 3D-printed Ni-C (3DP NiC), effectively reducing the interfacial energy between Mg(OH)2 and the electrode while enabling continuous removal of Mg(OH)2 precipitates at high current densities. As a result, the Ov-rich 3DP NiC/NMO demonstrates outstanding durability lasting up to 668 h at 500 mA cm−2 and 200 h at 1000 mA cm−2, which is 39.3 times and 16.7 times the lifespan of Ni foam/NiO@MoO2 (NiF/NMO), respectively. Moreover, it enables solar-powered seawater electrolysis for up to 20 days, reducing the hydrogen production cost to US$0.24 per kg, which is below the DOE 2025 and 2030 targets (US$1.40 and US$1.00 per kg of H2, respectively). This work presents a strategy to prevent sedimentation by reducing the interfacial energy, advancing hydrogen production directly from natural seawater, breaking the limitation of freshwater resources, and opening a sustainable path for global energy transformation.