Abstract: Seawater electrolysis for hydrogen production represents a critical pathway to advance the low-carbon transition of the energy structure. However, the complex ionic environment of seawater, especially the corrosion effect and catalytic active site poisoning effect induced by chloride ions, severely restricts the catalytic activity and long-term operational stability of electrode catalysts. Accordingly, developing high-efficiency and corrosion-resistant bifunctional electrode catalysts has become a core research focus in this field. A P, Se co-doped NiMoO₄ bifunctional electrocatalyst (P,Se-NiMoO₄) was fabricated via a one-step hydrothermal method combined with a low-temperature phosphorus-selenium doping strategy. Incorporation of P and Se dopants does not damage the rod-like microstructure of NiMoO₄. Meanwhile, in-situ generation of surface nanoparticles is induced, which substantially enlarges the electrochemical active surface area and surface roughness of the catalyst. The obtained catalyst delivers outstanding bifunctional catalytic activity and durability in both alkaline freshwater and natural seawater electrolytes. In 1 mol·L^–1 KOH alkaline solution, the hydrogen evolution reaction (HER) overpotential is merely 169.1 mV at a current density of 100 mA cm^–2, and the oxygen evolution reaction (OER) overpotential reaches 319.9 mV at 100 mA cm^–2. When applied to natural seawater electrolysis, the catalyst retains high catalytic efficiency and favorable Faradaic selectivity, along with remarkable long-term stability over 100 h continuous operation. The co-doping of P and Se effectively modulates the electronic configuration of NiMoO₄ and accelerates the interfacial charge transfer kinetics. Furthermore, the electron-rich doping sites suppress the adsorption and corrosion of chloride ions through electrostatic repulsion, greatly strengthening the anti-corrosion capability of the catalyst. This research offers innovative design strategies and experimental foundations for low-cost electrocatalysts with high performance toward seawater electrolysis.

Key words: seawater electrolysis, bifunctional catalyst, P and Se co-doped, NiMoO₄