Ziyao Chen, Yiwei Sun, Mengqing Hu, Mingli Li, Kaidi Zhang, Wanhong Zhang, Zhong Zheng, Ruth Knibbe, Kaicai Fan, Lingbo Zong, Yuhai Dou, Yabo Jia, Y. Z. Wang, Huai Qin Fu, Porun Liu, Huijun Zhao
ABSTRACT High‐entropy alloys (HEAs) offer a versatile platform for bifunctional electrocatalysis, yet their activity‐stability balance under industrial‐level current density remains insufficiently understood. Here, we report a self‐supported NiFeCoMoW HEA electrode fabricated by pulse electrodeposition on copper foam, forming a binder‐free hierarchical architecture with homogeneous elemental distribution. In 1.0 M KOH, NiFeCoMoW@CF delivers strong bifunctional activity, requiring an overpotential of 251 mV to reach 10 mA cm −2 for OER, and enables overall water splitting with a low cell voltage of 1.52 V at 10 mA cm −2 and 1.83 V at 1000 mA cm −2 . The electrolyzer operates stably at 1000 mA cm −2 for 100 h with minimal voltage increase. In situ Raman spectroscopy reveals a potential‐dependent surface evolution: a persistent Mo/W‐O signature is retained across HER and OER, while Ni/Fe/Co reconstruct into an oxyhydroxide‐rich surface state under OER, consistent with post‐test XPS/HRTEM. This coupled stabilization–reconstruction behavior, enabled by multicomponent coupling and pulse‐engineered accessibility, provides mechanistic insight and a practical strategy for durable, noble‐metal‐free alkaline water electrolysis.