A New Sensor with Increased Lifetime Based on a Mixed Diazonium Thick Film/Gold Nanoparticles Interface for Hg(II) Trace Detection

Abstract

This work describes a novel strategy for surface functionalization, the aim of which is to significantly increase the lifetime of an electrochemical sensor dedicated to Hg(II) trace determination. In order to tailor stable mixed organic/inorganic interfaces, gold nanoparticles were electrodeposited onto a glassy carbon electrode previously functionalized by a thick 4-thiophenol diazonium film, which affords a good anchoring to the nanoparticles. AFM and FEG-SEM were used to characterize the film thickness and the nanoparticles average size and density, respectively. By using square wave anodic stripping voltammetry, the sensor exhibited a linear response between 1 and 10 nM Hg(II) and a normalized sensitivity 0.03 μA nM À 1 min À 1 . Compared to previous works, the storage lifetime of the interface was at least three times longer, being more than three weeks.

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

“…Whatever the substituted aniline considered, HCl is typically used to afford the acidic media necessary for the first step of the diazotation reaction and then for the in situ electrografting of the as-formed diazonium. 37,47,48 However, here it had to be replaced by HNO 3 , because of the strong interaction of chloride anions with Ag. Indeed, Ag may be oxidized at a low potential in the presence of chloride to form AgCl according to the following reaction:Ag + Cl − → AgCl + e − E ° = −0.02 V SCE −1 .…”