Durable Natural Urine Electrolysis Enabled by Lewis Acid-Tailored Interfacial Microenvironment.

Abstract

Electrochemical urea oxidation reaction (UOR) is a promising alternative to sluggish oxygen evolution reaction (OER) for hydrogen production. However, its reliance on costly pure urea limits practical application. To address this issue, urine oxidation reaction (U_rOR) has been proposed, which utilizes natural urine as a cost-free feedstock. Nevertheless, due to the complex ionic matrix of urine, U_rOR suffers from catalyst acidification and chloride-induced corrosion, limiting long-term stability. Here, an interfacial microenvironment regulation strategy by modifying common Ni₂P catalyst with various hard Lewis acids (LA) is reported. The optimal V₂O_5-δ-Ni₂P hybrid exhibits remarkable U_rOR activity (1.62 V at 3 A cm^-2) and long-term durability (1000 h). Mechanistic analysis reveals that LA component selectively enriches interfacial OH^- ions, effectively suppressing the adsorption of impurities, especially Cl^- ions, and the generation of N-chlorourea byproduct. Notably, a near-kilowatt-scale natural urine electrolysis is first verified in a flow electrolyser (18 cells, area of 1386 cm²), achieving a high H₂ production rate of 115.84 L h^-1 with a urine purification rate of 97.41%, while recovering nitrogen-rich compound fertilizers (NH₄Cl/KCl). Furthermore, the electrolyzer exhibits broad applicability across wastewater with various urea concentrations (5-330 mM) and Cl^- ions concentrations (0.5-500 mM), including challenging 100 L wheatfield effluents.