Detalle de: Suppression of passivation on NiMoO4 microrod by ultrathin metal-organic-framework nanosheets in urea-assisted natural seawater splitting

Organic nucleophile-assisted natural seawater electrolysis has emerged as a promising strategy for green hydrogen production by significantly reducing energy consumption. Among Ni-based electrocatalysts, NiMoO 4 has drawn attention for its activity in both oxygen evolution reaction (OER) and urea oxidation reaction (UOR). However, its practical application is hindered by severe surface passivation, particularly at industrial current densities (e.g., > 300 mA cm -2 ). This study shows that integration of Ru-doped Ni-MOF nanosheets onto NiMoO 4 microrods to construct three-dimensional (3D) core-shell arrays enhances catalytic activity while suppressing NiMoO 4 passivation during urea-assisted natural seawater splitting. Ru doping induces charge redistribution on the surface of the outer Ni-MOF layer, a process crucial for enhancing catalytic performance in natural seawater-based electrolytes. This modulation yields a low overpotential of 120 mV and 238 mV at 10 mA cm -2 for UOR and OER, respectively, with a stable operation for 200 h at 135 mA cm -2 . State-of-the-art operando characterizations reveal that surface reconstruction of the NiMoO 4 core plays a crucial role in improving UOR activity, while no significant oxidation-induced reconstruction occurs on the outer RuNi-MOF layer. Owing to its outstanding bifunctional performance, the RuNi-MOF@NMO-based urea-assisted natural seawater electrolyzer requires only 1.87 V to operate at 0.5 A cm -2 .