Ion sieving membrane for direct seawater anti-precipitation hydrogen evolution reaction electrode

In seawater, severe hydroxide-based precipitation on the hydrogen evolution reaction (HER) electrode surface is still a major stumbling block for direct seawater electrolysis. Here, we design a direct seawater HER electrode with excellent anti-precipitation performance based on an Ni(OH)2 nanofiltration membrane in situ grown on nickel foam (NF) at room temperature. The positively charged Ni(OH)2 membrane with nanometer-scale cracks realises an ion sieving function, which apparently hinders the transfer of Mg2+/Ca2+ ions to suppress precipitation, while rapidly transporting OH- and H2O to ensure HER mass transfer. Therefore, the Ni(OH)2-membrane-decorated seawater HER electrode reduces precipitation by about 98.3% and exhibits high activity and stability. Moreover, in the application of a direct seawater electrolyser and magnesium seawater battery, the Ni(OH)2 membrane-decorated electrode also shows low precipitation and high stability. This work highlights a potential strategy to solve HER electrode precipitation in seawater via an ingenious electrode structure design. A positive charged Ni(OH)2 ion sieving membrane is in situ grown on 3D nickel foam based seawater HER electrode to dramatically reduce hydroxide-based precipitation on the electrode surface via hindering the transfer of Mg2+ ion.

Automated summary

This study presents a potential strategy to reduce hydroxide-based precipitation on the electrode surface in seawater electrolysis. A positively charged Ni(OH)2 nanofiltration membrane is grown on a nickel foam electrode, hindering the transfer of Mg2+ ions and significantly reducing precipitation. The electrode exhibits high stability and activity.