Salen decorated nanostructured ZnO chemosensor for the detection of mercuric ions (Hg2+)

Abstract

Self-assembled ZnO nanoparticles, nanodumbbells and nanorod/nanowire flowers were synthesized by the hydrothermal precipitation method, and tested them for the detection of mercuric ions (Hg2+) as the chemosensor. Various techniques like X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and photoluminescence (PL) were employed for the characterization of nanostructured ZnO powder. The surface of nanostructured ZnO was decorated with salen prepared from reported procedure. The binding ability of different nanostructured ZnO complexes with salen was tested by screening them with various metal ion solutions. The prepared solution of various ZnO complexes showed the selective affinity for mercuric ions, without having any interference from other potential interferent metal ions. The prepared complexes had a variable response and the selectivity for mercury ions, having the lowest detection limits of 20 nM (nanoparticle), 18 nM (nanodumbbell), 35 nM (nanorod flowers) and 10 nM (nanowire flowers), respectively. The detection limit/range of prepared complexes was varied with respect to the microstructures: (i) nanoparticles showed a larger dynamic range as they had more binding sites for Hg2+ owing to more binding sites for salen, and (ii) the nanowire flowers detected the better detection limit due to its cluster nature.