Urine electrooxidation for energy-saving hydrogen generation.

Wang, Pengtang; Gao, Xintong; Zheng, Min; Jaroniec, Mietek; Zheng, Yao; Qiao, Shi-Zhang · Nat Commun · 2025

basic_science · Level V

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Abstract

Urea electrooxidation offers a cost-effective alternative to water oxidation for energy-saving hydrogen production. However, its practical application is limited by expensive urea reactants and sluggish reaction kinetics. Here, we present an efficient urine electrolysis system for hydrogen production, using cost-free urine as feedstock. Our system leverages a discovered Cl-mediated urea oxidation mechanism on Pt catalysts, where adsorbed Cl directly couple with urea to form N-chlorourea intermediates, which are then converted into N<sub>2</sub> via intermolecular N-N coupling. This rapid mediated-oxidation process notably improves the activity and stability of urine electrolysis while avoiding Cl-induced corrosion, enabling over 200 hours of operation at reduced voltages. Accordingly, a notable reduction in the electricity consumption is achieved during urine electrolysis (4.05 kWh Nm<sup>-3</sup>) at 300 mA cm<sup>-2</sup> in practical electrolyser for hydrogen production, outperforming the traditional urea (5.62 kWh Nm<sup>-3</sup>) and water (4.70-5.00 kWh Nm<sup>-3</sup>) electrolysis.