Colloid carbonization-stabilized Ru nanoparticle catalyst for efficient ammonia synthesis at mild conditions

Abstract

Ruthenium-based catalysts are widely used in ammonia (NH3) synthesis because of a high affinity for N2 activation, while confronting the challenge of facile deactivation due to sintering. Herein, for the first time, we develop a highly active and sintering-resistant Ru2.1-CC catalyst via colloid carbonization (CC) for NH3 synthesis. It exhibits a superior NH3 synthesis rate around 9.4-fold that of Ru catalyst synthesized by impregnation method, displaying extremely high stability without aggregation of Ru nanoparticle after 100 h stability test. Our studies show that Ru2.1-CC possesses the average Ru particle size of 2.1 nm with narrow size distribution and thus exposes more active sites for N2 activation. Moreover, the formation of Ru-C interaction via colloid carbonization over Ru2.1-CC can stabilize Ru particle size to realize high stability, meanwhile reduce work function and upshift the d-band center of Ru metal to accelerate its electron transfer for N2 activation and NH3 synthesis. This study provides a new strategy for simple synthesis of noble metal-based catalysts that are highly active and stable for NH3 synthesis.