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Hydrogen produced from neutral seawater electrolysis faces many challenges including high energy consumption, the corrosion/side reactions caused by Cl-, and the blockage of active sites by Ca2+/Mg2+ precipitates. Herein, we design a pH-asymmetric electrolyzer with a Na+ exchange membrane for direct seawater electrolysis, which can simultaneously prevent Cl- corrosion and Ca2+/Mg2+ precipitation and harvest the chemical potentials between the different electrolytes to reduce the required voltage. In-situ Raman spectroscopy and density functional theory calculations reveal that water dissociation can be promoted with a catalyst based on atomically dispersed Pt anchored to Ni-Fe-P nanowires with a reduced energy barrier (by 0. 26 eV), thus accelerating the hydrogen evolution kinetics in seawater. Consequently, the asymmetric electrolyzer exhibits current densities of 10 mA cm-2 and 100 mA cm-2 at voltages of 1. 31 V and 1. 46 V, respectively. It can also reach 400 mA cm-2 at a low voltage of 1. 66 V at 80 °C, corresponding to the electricity cost of US1. 36 per kg of H2 (0. 031/kW h for the electricity bill), lower than the United States Department of Energy 2025 target (US1. 4 per kg of H2).
Shi et al. (Tue,) studied this question.