Strategically engineered NiSe/Co(OH)2 heterostructure via active site optimization for efficient urea electrooxidation

Abstract

Replacing the anodic water oxidation reaction with urea oxidation offers a dual advantage: significantly lowering the cost of hydrogen (H₂) production and addressing urea-rich wastewater treatment. Nonetheless, the sluggish kinetics of the urea oxidation reaction (UOR) call for the creation of advanced electrocatalysts with improved efficiency and long-term stability. In this study, we report a novel heterostructure electrocatalyst comprising nickel selenide (NiSe) rods coated with cobalt hydroxide [Co(OH)₂] flakes, synthesized via electrodeposition. The rationally engineered NiSe/Co(OH)₂ heterostructure leverages synergistic interactions at the interface to enhance catalytic performance. Strong electronic coupling within the heterostructure promotes efficient charge transfer, while the heterojunction induces charge redistribution and establishes a built-in electric field, leading to accelerated reaction kinetics and improved urea adsorption. Compared to its individual components, the NiSe/Co(OH)₂ heterostructure demonstrates superior catalytic activity, achieving an onset potential of 1.35 V at 10 mA cm⁻² and a Tafel slope of 52.9 mV dec⁻¹. The electrocatalyst also exhibits an impressive turnover frequency of 6.5 × 10⁻³ s⁻¹ at 1.4 V, highlighting its exceptional intrinsic activity. Furthermore, it maintains remarkable stability, with negligible performance degradation over 24 h of continuous operation at 10 mA cm⁻². These results highlight the promise of the NiSe/Co(OH)₂ heterostructure as a cost-effective and durable solution for hydrogen production and wastewater treatment through urea decomposition.