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Updated: Sep 18, 2025

Ammonia Synthesis at Low Pressure
Published on: August 23, 2017
Spontaneous formation of urea from carbon dioxide and ammonia in aqueous droplets
Mercede Azizbaig Mohajer1, Pallab Basuri1, Andrei Evdokimov2
1Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
Abstract:
Urea is a key molecule in the search for the origin of life and a basic chemical produced in large quantities by industry. Its formation from ammonia and carbon dioxide requires either high pressures and temperatures or, under milder conditions, catalysts or additional reagents. In this study, we observed the spontaneous formation of urea under ambient conditions from ammonia and carbon dioxide in the surface layer of aqueous droplets. Single, optically trapped droplets were probed by using Raman bands as markers. We found the surface layer to act like a microscopic flow reactor, with chemical gradients providing access to unconventional reaction pathways. This observation revealed a general mechanistic scheme for distinctive droplet chemistry. Interfacial chemistry is a possible nonenergetic route for urea formation under prebiotic conditions.
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