Metallic Nickel Activation of Non-Reconstructed Amorphous Nickel Selenide Interface for Ampere-level Natural Seawater Splitting

Direct seawater electrolysis for hydrogen generation is restricted by sluggish kinetics and limited durability. Various ionic interference significantly challenges to non-noble metal catalysts, compromising both intrinsic activity and structural stability. Thus, a non-reconstructive amorphous nickel selenide composite (Ni/C-a-NiSe ₂ ) was synthesized via γ-ray irradiation. Citrate groups anchored through robust Se–O bonds suppress electrochemical reconstruction, preserving structural integrity from anionic leaching. Oxyphilic metallic nickel activates the interfacial hydrogen-bond network and serves as a dynamic *OH reservoir, facilitating intermediate spillover. The weak-coordinated water and spatially separated Volmer–Heyrovsky steps accelerate seawater–splitting kinetics. Ni/C-a-NiSe ₂ shows excellent catalytic performance in neutral seawater, reaching an overpotential of 159.8 mV at 100 mA cm ^–2 and a Tafel slope of 68.5 mV dec ^–1 . In an electrolyzer, it achieves 1 A cm ^–2 at 1.71 V and maintains stable operation at 60 °C for over 2000 h with minimal degradation rate (0.0086 mV h ^–1 ).