Self‐Supported Ni/Ni(OH)₂ Electrodes for High‐Performance Alkaline and AEM Water Electrolysis

Abstract A novel tape‐cast Ni/Ni(OH) 2 electrode is developed for water electrolysis applications. Through precise control of sintering temperature and in situ formation of Ni(OH) 2 nanosheets, the electrode achieves an optimized hierarchical porous structure with interconnected channels, facilitating efficient gas bubble transport and release. The electrode exhibits remarkable hydrogen evolution reaction activity with overpotentials of 40 and 124 mV at 10 and 100 mA cm −2 , respectively, comparable to noble metal catalysts. The unique microstructure enables rapid bubble detachment and enhanced mass transport, leading to a high current density of 0.91 A cm −2 at 1.8 V in alkaline water electrolysis. The inherent Ni/Ni(OH) 2 composition demonstrates excellent stability over 1500 h of continuous operation and maintains consistent performance under intermittent conditions, making it particularly suitable for renewable energy integration. For anion exchange membrane water electrolysis, the electrode's smooth surface morphology prevents membrane damage while maintaining efficient mass transport, delivering 0.4 A cm −2 at 1.8 V. This study demonstrates that rational design of electrode microstructure through tape‐casting offers a promising pathway toward high‐performance, durable, and cost‐effective water electrolyzers.