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

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 Ni₂P 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.