Chlorine-mediated electrosynthesis of hydrazine from urea

Abstract Hydrazine is an important chemical widely used in fuels and emerging energy systems, but its industrial synthesis heavily relies on energy-intensive processes involving hazardous oxidants. Here we report a mild and energy-saving electrocatalysis process that enables efficient and selective production of hydrazine from natural urea feedstocks using renewable electricity. This is achieved through a chlorine-mediated urea electrooxidation strategy, where co-adsorbed chlorine and urea can directly couple on the Pt surface to selectively form N -chlorourea. The resulting N -chlorourea subsequently undergoes deprotonation and rearrangement under alkaline conditions, with magnesium hydroxide serving as a catalyst for hydrazine production. In a practical flow electrolyser, this process delivers a hydrazine production of 1.04 mmol cm −2 h −1 and stable operation for 240 h, surpassing previously reported studies. More importantly, the process shows good compatibility with diverse real-world urea-containing waste streams, highlighting its applicability for practical hydrazine production and wastewater valorization.