Interfacially engineered Ru-doped NiO nanoflowers anchored on graphene as bifunctional electrocatalysts for...

Seawater electrolysis offers a promising strategy for scalable green hydrogen production, yet the high chloride ion content and complex ionic composition of seawater readily induce electrode corrosion and parasitic reactions. Herein, we report a corrosion-tolerant and highly conductive bifunctional catalyst comprising Ru-doped NiO nanoflowers anchored on coconut shell-derived graphene (Ru-NiO/CG). Ru incorporation and strong Ru-O-Ni electronic coupling regulate the surface chemistry of NiO, whereas the carbon scaffold constructs an efficient electron-transport network. Benefiting from this integrated architecture, Ru-NiO/CG exhibits robust bifunctional activity toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline seawater, requiring low overpotentials of 351 and 395 mV at 500 mA cm^-2, respectively. The electrode also sustains continuous electrolysis at 500 mA cm^-2 in alkaline seawater for 100 h with negligible performance degradation. Moreover, the symmetric Ru-NiO/CG‖Ru-NiO/CG cell delivers 100 mA cm^-2 at only 1.69 V in alkaline seawater. Notably, an oxygen faradaic efficiency of approximately ∼97.3% is achieved in alkaline seawater, demonstrating the high OER selectivity. Density functional theory (DFT) calculations indicate that anchoring Ru species on NiO nanoflowers induces pronounced interfacial charge redistribution, optimizing the adsorption strength of key reaction intermediates and strengthens Ru-O-Ni electronic coupling. This work presents a practical interface-engineering strategy for constructing efficient and durable bifunctional electrocatalysts toward alkaline seawater splitting.