Fabrication of a Ni foam-supported platinum nanoparticles-silver/polypyrrole electrode for aqueous ammonia sensing

Herein, an electrochemical ammonia sensor based on Ni foam-supported silver/polypyrrole and platinum nanoparticles electrode (Pt-Ag/PPy-NiF) was designed and constructed. The Ag/PPy layer was firstly grown on Ni foam surface via oxidation reduction reaction, and then Pt nanoparticles with great electrocatalytic activity were electrodeposited on the surface of Ag/PPy-NiF via cyclic voltammetry methodology. Electrochemical experiments demonstrated that the Pt-Ag/PPy-NiF electrode showed a great electrocatalytic ability of the oxidation of ammonia and an electrochemical aqueous ammonia sensor was proposed accordingly. The ammonia sensor showed a sensitivity of 0.089 mA mu M-1, a detection limit of 37 nM (S/N = 3) and a wide linear range, as well as presenting a good anti-interference capability against many common ions in water. These excellent performances can be mainly attributed to large specific surface of electrode and great electrocatalytic ability of Pt nanoparticles.