Catalytic Ammonia Decomposition Using Single High-Frequency Ultrasound

Ammonia (NH3) is a nexus molecule central to nitrogen functionality in numerous key compounds and has recently gained renewed attention as a promising hydrogen carrier. However, NH3 decomposition is an endothermic process that traditionally relies on an elevated energy input, often derived from thermal, electrical, or solar sources. Herein, we report an innovative approach for NH3 decomposition driven by sono energy─an unconventional energy form generated through acoustic cavitation under ultrasonic irradiation, producing transient localized conditions (∼5000 K, ∼100 MPa). These extreme environments enable NH3 decomposition without reliance on conventional energy sources. A Ni/TiO2 sonocatalyst was rationally designed to facilitate both acoustic bubble nucleation and catalytic activity. Sonocatalytic NH3 decomposition was successfully demonstrated in a custom-designed reactor operating at 1.0 MHz over a time scale of minutes. Theoretical studies elucidate the underlying reaction mechanism, offering molecular-level insights into the sonocatalytic interface. This work pioneers a sustainable route for NH3 decomposition and highlights the potential of sonocatalysis in future energy and environmental applications.