Mountain‐Shaped Nickel Nanostripes Enabled by Facet Engineering of Nickel Foam: A New Platform for High‐Current‐Density Water Splitting

Abstract Electrocatalysts play a crucial role in hydrogen production via water splitting, yet their effectiveness is hampered by the bubble effect, particularly under high‐current‐density conditions. Herein, nickel foam with mountain‐shaped nanostripes (NFMN) is developed as a universal substrate for electrocatalysts to remove gas bubbles efficiently, ensuring high‐performance high‐current‐density water splitting. The NFMN is fabricated through facet engineering of nickel foam (NF) via thiocyanate‐guided acid etching. Specifically, when immersed into an acidic thiocyanate solution, the (220) plane of NF is preferentially adsorbed by SCN − , protecting it, while the (111) and (200) facets remain exposed and are selectively etched by the acid. As the etching proceeds parallelly to the (220) direction, mountain‐shaped nanostripes are obtained. The nanostripes confer the benefits of superaerophobicity and local circulation, allowing the NFMN to efficiently release gas bubbles. As a proof‐of‐concept application, the NFMN is employed as a novel substrate to support the FeOOH anode and Ni 2 P cathode for a prototype electrolyzer, which exhibits a low cell voltage of 1.847 V at a large current density of 500 mA cm −2 with high stability. This work opens up new opportunities to construct efficient substrates for high‐current‐density water splitting and beyond.