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

By growing a Ni(OH)2 membrane with nanometer-scale cracks on the direct seawater HER electrode, the precipitation of hydroxide-based compounds can be effectively suppressed while maintaining the mass transfer of HER, resulting in improved activity and stability of the electrode. This work is of great significance for solving the precipitation issue of HER electrodes in seawater.