▎ 摘　　要

The study on electrochemical behavior of ammonia is a far-reaching topic, not only for its electro-oxidation elimination from effluent treatments, but also for detection of ammonia concentration by employing electrochemical sensors. Herein, we report a simple electro-chemical ammonia detector with high sensitivity/selectivity, superfast response, and long-time stability, using ultrafine Ir nanoparticles decorated 3D graphene hollow spheres. Morphological and structural analysis reveals that the inner ultrathin graphene shell effectively maximize the specific surface area and outer tiny Ir nanoparticles are optimal for offering active adsorption sites of NH3. Because of the well-defined morphology and 3D interconnected architecture, the rGO/Ir HSs modified glassy carbon electrode (GCE) exhibits superior activity for the electro-oxidation of NH3 performed in neutral medium, which is 4 times higher than that of commercial Ir/C catalyst. The amperometry technique is served to investigate the ammonia-detected performance of the rGO/Ir HSs-modified GCE, demonstrating high sensitivity and quick response from wide linear range of 0.015-75mM (R-2 = 0.998) with a detection limit of 6.5 mu M. This work offers a new type of graphene-based nanohybrids to enhance the electro-oxidation and gas sensing abilities toward ammonia, leading to the development of manufacturing high-performance electro-analytical sensors. (C) 2019 Elsevier Ltd. All rights reserved.