Influence of the gold nanoparticles electrodeposition method on Hg(II) trace electrochemical detection
Résumé
Gold nanoparticles (AuNPs) were deposited on Glassy Carbon (GC) substrate by using three electrochemical techniques: Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiostatic Double-Pulse (PDP). For each electrodeposition method, the resulting AuNPs-modified electrodes were characterized by CV in H2SO4 and Field Emission Gun Scanning Electron Microscopy (FEG-SEM). CA was found to be the best electrodeposition mode for controlling the morphology and the density of AuNPs. The modified electrodes were used for low Hg(II) concentration detection using Square Wave Anodic Stripping Voltammetry (SWASV). AuNPs obtained by CA afforded the best amperometric response while involving the lowest amount of charge during the electrodeposition step (QAu(III)). This analytical response is correlated to both the smallest particle size (ca. 17 nm in diameter) and the highest particle density (332 particles μm−2), thus displaying high electrode effective surface area. In these optimal conditions, using a Hg(II) preconcentration time of 300 s, the nanosensor array exhibited a linearity range from 0.80 to 9.9 nM with a sensitivity of 1.16 μA nM−1. A detection limit of 0.40 nM (s/n = 3) was reached.