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Designing and optimizing structure is an effective method to enhance electrocatalytic performance of transition metal-based catalysts. In this work, an innovative nanostructured electrode, consisted of peapod-like Ni 2 P@N-doped carbon nanorods array coating on carbon fiber (CF@p-Ni 2 P@NC), is devised and synthesized. The N-doped carbon layer is crucial for maintaining the peapod-like nanostructure, which allows for multi-channel electrolyte transport and gas product release. And the carbon layer coating Ni 2 P nanoparticles also enhance electrical conductivity and stability, thus ensuring fast electron transport from/to active sites and the long-term stability of catalyst during urea oxidation reaction (UOR)/hydrogen evolution reaction (HER). Benefit from the reasonable structure, CF@p-Ni 2 P@NC present perfect performance with getting 100 mA cm−2 at potential/overpotential of 1.417/0.194 V for UOR/HER in 1.0 M KOH containing 0.5 M urea. In addition, the overall urea-electrolysis system using CF@p-Ni 2 P@NC bifunctional electrode only requires 1.590 V to obtain 100 mA cm−2. Novel peapod-like Ni 2 P@N-doped carbon nanorods array on carbon fiber is prepared and exhibits perfect catalytic activity toward both UOR and HER in urea-assisted electrolytic water splitting. [Display omitted] • Peapod-like Ni 2 P@N-doped carbon nanorods array on CF is designed and synthesized. • The CF@p-Ni 2 P@NC exhibits perfect catalytic activity toward both UOR and HER. • The superior performance is ascribed to the peapod-like nanorods array structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanostructured amorphous FeCoNiPB HEA ribbon is fabricated as OER electro-catalysts. • The HEA surface is conversed to FeCoNiPB/(FeCoNi) 3 O 4-x nanoparticles after acid etching. • The obtained (FeCoNi) 3 O 4-x species have rich lattice distortion, vacancy, and break defects. • The HEA ribbon need a low overpotential of 229 mV to afford 10 mA cm−2 current density. The high-entropy materials have attracted rising attention for electrolysis application, which may have unusual performances due to the proximal configuration of dissimilar atoms. Meanwhile, design of nanostructure and fine-tuning of crystal structure could further improve their properties. In this work, amorphous FeCoNiPB high-entropy alloy (HEA) ribbons are prepared first, whose superficial species are conversed to FeCoNiPB/(FeCoNi) 3 O 4-x composite nanoparticles with a diameter of ~15 nm by the air after acid etching treatment. It is found that the obtained composite nanoparticles deposited on the surface of FeCoNiPB HEA ribbon with 3D porous array. Besides, the (FeCoNi) 3 O 4-x crystal that derived from amorphous HEA has rich defect structure, including lattice distortions, vacancy defects and discontinuous crystalline fringes. Hence, due to the advantages of heterogeneous nanostructure and defect activation, the FeCoNiPB/(FeCoNi) 3 O 4-x nanoparticle modified HEA ribbon has a high catalytic activity for oxygen evolution reaction, which need low overpotentials of 229 mV and 406 mV to export 10 and 100 mA cm−2 current density with a good stability. [ABSTRACT FROM AUTHOR]