Photochemical assisted formation of silver nano dendrites and their application in amperometric sensing of nitrite

Abstract

Herein, we describe a photochemical route for the synthesis of silver (Ag) dendrites nanostructure using phenothiazine (PTZ) as a reductant as well as stabilizer without any extra control viz. surfactant, pH etc. This hybrid material derived from nanoscale silver capped with phenothiazine and its oxidation product (PTZH) has been explored for the development of a highly sensitive electro-sensor of nitrite ions. Further, a possible reaction mechanism for the formation of the silver dendrites nanostructure has also been proposed. The synthesized hybrid material (Ag–PTZH) has been characterized by UV-visible spectroscopy, cyclic voltammetry, transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. This hybrid material modified electrode efficiently catalyzes the electrochemical oxidation of nitrite at the potential of 0.44 V vs. AgCl/Ag and shows a linear response towards nitrite ion sensing with 2.43 μA μM⁻¹ sensitivity and 2.3 nM limit of detection at a S/N (signal-to-noise ratio) of 3. The electrochemistry behind this sensing of nitrite is probably due to high connectivity throughout the silver dendrites nanostructure capped with phenothiazine and its oxidation product which exhibits high electron transfer kinetics via interaction of Ag–PTZH with oxygen atoms of NO₂⁻.