Electrochemical detection of chloride at the multilayer nano-silver modified indium-tin oxide thin electrodes

A novel method for sensitive determination of chloride anion at multilayer nano-silver modified indium-tin oxide (ITO) electrode has been developed. The multilayer films were fabricated via self-assembly/electrochemical-assembly methods, in which the 3-aminopropyltriethoxysilane (APTS) was used to modify ITO conducting glass, layer-by-layer (LBL) method was applied to prepare the multilayer films and poly (diallyldimethylammonium chloride) (PDDA) was employed as a bridging ligand. The resulting electrode (Ag/{PDDA/Ag}m/APTS/ITO) surface was characterized with SEM and UV–vis. The electrochemical behavior of Cl− at the Ag/{PDDA/Ag}m/APTS/ITO electrode was studied by cyclic voltammetry. The results indicated that the modified electrode exhibited substantial enhancement in electrochemical sensitivity for Cl− due to its large surface area and particular absorbability. The Ag/{PDDA/Ag}m/APTS/ITO electrode detected Cl− by voltammetry based on the oxidation of Ag/Cl− that generated from a specific reaction of chloride ions with nano-silver. After accumulation of 3 min for Cl− at Ag/{PDDA/Ag}m/APTS/ITO electrode, the peak height (Ag/Cl−) increased linearly with the concentrations of Cl− in the range of 1.0 × 10−8–1.0 × 10−6 mol L−1. The detection limit was 5.2 × 10−9 mol L−1 at 3σ level. This modified electrode could be successfully applied in water samples with low cost and high sensitivity.