Seawater Electrolysis Sustained via the Permselective Layer on Catalysts

Seawater electrolysis is a sustainable strategy to produce green hydrogen but necessitates robust anodes capable of resisting chlorine corrosion and side reactions. Here, we design the conformal phosphate coating on nickel-iron molybdate microrods as an ion-selective permeable layer to sustain alkaline seawater oxidation against chlorine attack even at ampere-level high current densities. Insights into the chemical microenvironment shed light on the roles of surface phosphates both in repelling chloride ions and facilitating hydroxyl diffusion to sustain the high-flux oxygen evolution reaction. This surface-phosphated microrod anode catalyzes stably alkaline seawater oxidation at a high current density of 1 A cm^-2 for over 700 h without corrosion. Using such an anode in an actual electrolyzer, we demonstrate seawater electrolysis at 0.5 A cm^-2 sustained for 500 h at 2.0 V, with an electricity consumption of 4.78 kW h Nm^-3 and a cell efficiency of 74%.