Ampere-level membrane-less water electrolysis enabled by rose-petal-effect-mimetic interface

Summary To maximize product purity, current density and efficiency has never been demonstrated simultaneously for the membrane-less water electrolyzers that eliminate the use of a membrane or a diaphragm, as well as their unfavorable issues. Here, we successfully addressed the trade-offs by leveraging the rose-petal-effect-mimetic (RPEM) design strategy. We mimicked nature by alternating water-repellent and water-adhesive building blocks; the resultant RPEM electrode is in the Cassie-impregnating wetting state, which is ideal for efficient bubble-less gas evolution reactions. A bubble-less HER at a current density of 4.2 A cm −2 , one order of magnitude larger than that of any known bubble-less electrodes, was demonstrated by the RPEM electrode. Based on this, we further constructed the RPEM electrolyzer and demonstrated membrane-less water electrolysis at 1 A cm −2 current density, simultaneously with 61.5% electrolysis efficiency and 0.003% hydrogen crossover, remarkably outperforming the state-of-the-art membrane-less water electrolyzer.