Surface‐Strained NiMo Cathodes Enable Kinetics‐Decoupled Hydrogen Bubble Management for Stable Near‐Neutral Water Electrolysis

Gas evolution during water electrolysis forms bubble layers that block active sites and increase transport and ohmic losses. Decoupling bubble‐mediated mass transport from intrinsic hydrogen evolution reaction (HER) kinetics remains challenging because surface modifications affect both activity and bubble dynamics. Here, a surface‐strained NiMo cathode ( s ‐NiMo) enables kinetics‐decoupled hydrogen bubble management in a near‐neutral electrolyte. In 0.5 m potassium phosphate buffer (pH 7.0), NiMo and s ‐NiMo exhibit nearly identical intrinsic HER kinetics, consistent with similar H* adsorption energetics. Under bubble‐regulated operation, s ‐NiMo shows a 63 mV lower steady‐state overpotential at −20 mA cm −2 . High‐speed imaging reveals smaller, faster‐departing H 2 bubbles, reducing the mean residence time from 0.5 s to 0.2 s. Interfacial analyses indicate enhanced hydrophilicity and more negative surface‐charge‐related characteristics. Ensemble calculations based on the Universal Model for Atoms show that the surface‐associated *H 2 state is 0.52 eV higher in the s ‐NiMo‐representative environment, while electrochemical fluorescence lifetime imaging microscopy reveals a 1.5‐fold higher nanobubble event density. In a single‐cell electrolyzer at 300 mA cm −2 , s‐NiMo maintains a 280 mV lower cell voltage over 100 h. These findings establish bubble management as an independent design axis for stable near‐neutral water electrolysis.