Room-Temperature Catalyst-Free Ammonia Decomposition for Hydrogen Production on Water Microdroplets

Ammonia has been considered a viable carbon-free hydrogen carrier, yet its decomposition to hydrogen mainly relies on noble-metal-based catalysts and high temperatures. Here, through leveraging extraordinary physicochemical properties at the gas-liquid interface of water microdroplets, we present a catalyst-free and scalable approach for hydrogen production from ammonia under ambient conditions. A maximum hydrogen evolution rate of 226.8 μmol/h was observed, which outperformed most conventional catalytic methods at room temperature. Comprehensive experimental investigations and theoretical calculations revealed the underlying ammonia splitting mechanisms: hydroxyl radical and hydrogen radical, generated at the gas-liquid interface of microdroplets, synergistically triggered the interfacial ammonia decomposition following a thermodynamically favorable redox pathway, and the reaction rates can be enhanced by the high electric fields and reactants concentration accumulation at the gas-liquid interface. This work provides a new paradigm for green hydrogen production, advancing microdroplet chemistry and a sustainable hydrogen society.