A diazonium-functionalized silver electrode for the sensitive amperometric detection of p-nitrophenol in water over a wide range of concentrations

Abstract

This work presents a novel approach for the electrochemical detection of p-nitrophenol (pNP) focusing on the development of a simple and efficient strategy to overcome pNP adsorption. The proposed method involves the functionalization of a silver (Ag) electrode with an electrografted, thin diazonium film. After characterization by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, the as-functionalized electrode allowed a wide linear detection range to be established in aqueous solutions, spanning from 1 to 500 μM pNP. This outcome indicates that the diazonium film effectively addresses any issues related to adsorption with good repeatability and reproducibility. Furthermore, the sensor's analytical performances were evaluated yielding a sensitivity and a limit of detection of 0.3819 μA cm⁻² μM⁻¹ and 600 nM, respectively. The sensor was also found to exhibit a good selectivity towards pNP and phenolic compounds and was successfully tested on a real water sample.