Ultrasensitive gaseous NH3 sensor based on ionic liquid-mediated signal-on electrochemiluminescence

Abstract

This work reports that ammonia (NH₃) can be used as an efficient co-reactant for tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) electrochemiluminescence (ECL) in ionic liquids (ILs), on the basis of which a signal-on ECL sensor for directly detecting gaseous NH₃ has been developed. The NH₃ ECL sensor has a very high sensitivity, with a detection limit of 10 ppt NH₃ (at signal-to-noise ratio of 3) without any preconcentration. The high sensitivity is mainly due to the zero ECL background of Ru(bpy)₃²⁺ in the ILs, strong co-reactant ECL activity of NH₃, and high solubility of NH₃ in imidazolium-based ILs. Additionally, the ECL sensor shows an excellent selectivity against common interfering gases and a wide linear response range from 10 ppt to 10 ppm.