One-pot facile preparation of Ag nanoparticles for chloride ion sensing

Simplified synthesis of silver nanoparticles on graphene oxide and their applications in electrocatalysis

In this work the possibility of synthesizing in situ silver nanoparticles (AgNPs) on graphene oxide (GO) surfaces without commonly used additional reducing or alkalizing agents or increased temperature was investigated. Using diverse microscopic (atomic force microscopy, transmission electron microscopy) and spectroscopic methods, it was proved that very small AgNPs were formed on GO by simple incubation for 2 h in a mixture of GO dispersion and AgNO₃. The prepared nanomaterial (GO_Ag) was also assessed using electrochemical methods, and it exhibited electrochemical behavior similar to the GO_Ag nanomaterial prepared with a help of citric acid as a reducing agent. Furthermore, it was found that (i) the electrochemical reduction of the GO_Ag on the electrode surface decreased the voltammetric response even though this step increased the surface conductivity and (ii) GO_Ag can be employed for the sensing of chlorides with a detection limit of 79 μM and a linear range of up to 10 mM. It could also provide an electrochemical response toward the chloroacetanilide herbicide metazachlor. Hence, the reducing capabilities of GO were proved to be applicable for in situ synthesis of metal nanoparticles with the highest possible simplification, and the as-prepared nanomaterials could be employed for fabrication of different electrochemical sensors.

Determination of halides using Ag nanoparticles-modified disposable electrodes. A first approach to a wearable sensor for quantification of chloride ions

This work reports a simple voltammetric method for the determination of chloride, bromide, and iodide ions using screen-printed carbon electrodes modified with silver nanoparticles electrochemically deposited on the working electrode surface. UV/Vis absorption spectroelectrochemistry was used to study the electrodeposition of silver nanoparticles on the working carbon electrode on PET or Gore-Tex^® supports, and their subsequent oxidation in the presence of halide ions. The main figures of merit of the developed sensors, such as reproducibility and detection limit, have been calculated. Reproducibility values of 2.22%, 2.83% and 3.23% were obtained for chloride, bromide and iodide determinations, respectively. Additionally, the lowest detected amount of chloride, bromide and iodide ions were 3.0·10^-6 M, 5.0·10^-6 M and 5.0·10^-6 M, respectively. Taking into account the relevance of the determination of chloride ion concentration in sweat, the voltammetric method for the determination of halides has been successfully transferred to a Gore-Tex^® support to build a first approach to a wearable sensor that facilitates the quantification of this ion in sweat samples. The Gore-Tex^® sensor provides a good reproducibility (RSD = 1.61%).