The quest for sustainable hydrogen production has intensified interest in cost-effective, high-performance electrocatalysts for overall water splitting (WS). Herein, we report the in situ synthesis of a dendritic Ni–Cu–Co–P electrocatalyst via a one-step electrodeposition method assisted by a dynamic hydrogen bubble template (DHBT) on nickel foam (NF). A systematic study evaluated the effect of deposition time on morphology, composition, and electrochemical performance. Among the samples, the electrode prepared at 80 seconds (S-80) exhibited optimal structural and catalytic properties. FESEM and TEM analyses confirmed the dendritic morphology, while EDS mapping verified uniform multimetallic distribution. Electrochemical testing in 1.0 M KOH revealed excellent bifunctional activity. The optimized electrode delivered low overpotentials of 81 and 248 mV to achieve 10 mA cm−2 for the HER and OER, respectively, surpassing those of many non-noble catalysts and approaching those of noble-metal benchmarks. Tafel slope analysis and electrochemical impedance spectroscopy (EIS) confirmed favorable reaction kinetics and reduced charge transfer resistance (Rct), while cyclic voltammetry (CV) demonstrated a high electrochemically active surface area (ECSA), indicative of abundant active sites. Long-term chronopotentiometry over 100 hours confirmed outstanding durability under HER and OER conditions. Additionally, wettability and bubble-release assessments revealed superhydrophilic and superaerophobic properties, facilitating gas detachment and enhancing catalytic efficiency. A two-electrode electrolyzer using S-80 as both the cathode and anode achieved 10 mA cm−2 at a cell voltage of just 1.56 V. This work presents a scalable and effective strategy for developing advanced bifunctional electrocatalysts and highlights the synergistic advantages of multimetallic phosphide integration and dendritic nanoengineering in overall water splitting.

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