Stereolithgraphy of Metallic Electrode with Janus Porosity toward Controllable Bubble Behavior and Ultra‐Stable Water Electrolysis

The catalytic performance and the stability of the water electrolysis system have perplexed the practical splitting water. Herein, 3D‐printed metallic electrodes with Janus porosity are reported, which can achieve the efficient bubble emission and provide high surface area. After a further one‐step treatment, the catalysts of Ru–Ni(OH) 2 and Fe–Ni(OH) 2 nanoarrays are in situ grown on the electrodes. Theoretical calculations and systematical experiments confirm the synergistic effect of the gradient morphology and the in situ grown catalysts. The electrolyzer shows unprecedented activity with an overpotential of 98 mV for hydrogen evolution reaction and 343 mV for oxygen evolution reaction at the current density of 500 mA cm −2 and outperformed stability, which can deliver 500 mA cm −2 at the voltage of 1.638 V for 2100 h with no significant decay, far exceedingly most state‐of‐the‐art electrolyzers. This 3D electrode with controllable bubble motions offers a viable solution for future industrial sustainable hydrogen production technology.