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Abstract:
The urea oxidation reaction (UOR) offers a sustainable and thermodynamically favorable alternative to the oxygen evolution reaction, enabling coupling of urea-rich wastewater remediation with energy-efficient hydrogen production. However, the sluggish six-electron-transfer kinetics of UOR necessitate advanced electrocatalysts to accelerate reaction dynamics. Heterostructure engineering provides an effective strategy to regulate interfacial charge redistribution and enhance catalytic activity. Herein, we report a rationally designed MoS2/Ni3Se2 heterostructure with an intrinsic built-in electric field, constructed on nickel foam via hydrothermal growth followed by electrodeposition, exhibiting efficient bifunctional electrocatalytic activity toward UOR and the hydrogen evolution reaction. Density functional theory calculations reveal spontaneous interfacial charge transfer at the MoS2/Ni3Se2 interface, generating localized electrophilic and nucleophilic regions that facilitate urea adsorption, promote bond activation, and accelerate decomposition kinetics. Benefiting from this interfacial electronic modulation, the catalyst requires only 1.20 V vs. RHE to achieve 10 mA cm−2 for UOR in 1 M KOH + 0.5 M urea and an overpotential of 81 mV to reach the same current density for HER in 1 M KOH. Furthermore, the assembled UOR//HER electrolyzer operates at 1.31 V at 10 mA cm−2 and maintains stable performance for over 100 h. This work advances heterostructure-based urea-assisted hydrogen production for sustainable electrocatalysis.

Keywords:
built-in electric field, electrocatalysis, hydrogen production, MoS2/Ni3Se2 heterostructure, urea oxidation reaction

Abstract:
Urea-assisted electrolysis boosts hydrogen production by substituting the sluggish oxygen evolution reaction (OER) with the energetically favorable urea oxidation reaction (UOR), thereby lowering energy consumption. Rational heterojunction engineering modulates charge distribution and generates abundant active sites, facilitating urea adsorption and C─N bond cleavage. Herein, we report a facile electrodeposition strategy to construct g-C3N4/CoMoS2 hybrid electrocatalysts. The built-in electric field at the heterojunction creates electrophilic regions on g-C3N4 and nucleophilic regions on CoMoS2, selectively activating urea and promoting rapid bond cleavage. Anchoring g-C3N4 onto CoMoS2 enables remarkable bifunctional activity toward both UOR and HER, achieving potentials of 1.27 V vs. RHE in 1 m KOH + 0.33 m urea and -80 mV vs. RHE in 1 m KOH at 10 mA cm−2, respectively. Density functional theory (DFT) calculations reveal that interfacial electron transfer enriches CoMoS2 with electrons and depletes g-C3N4, enhancing charge transfer, optimizing urea adsorption, and lowering reaction energy barriers. Notably, the g-C3N4/CoMoS2//g-C3N4/CoMoS2 cell delivers 10 mA cm−2 at 1.34 V with excellent stability, demonstrating superior efficiency. This work provides a rational framework for designing efficient, energy-saving urea-assisted hydrogen production systems and reveals how intrinsic electric fields can precisely control charge distribution during catalysis.

Keywords:
built-in electric field, heterojunction, hydrogen production, urea oxidation

Abstract:
Hydrazine oxidation (HzOR) assisted hydrogen production offers a promising
alternative to energy-intensive and sluggish oxygen evolution reaction (OER),
improving its efficiency. However, its practical implementation demands
the development of advanced electrocatalysts capable of overcoming intrinsic
kinetic and charge transfer limitations. Herein, the study reports a hybrid catalyst by anchoring a 

Keywords:
Hydrazine oxidation, Hydrogen evolution, Covalent organic framework, interfacial interaction