A functional graphene oxide-ionic liquid composites-gold nanoparticle sensing platform for ultrasensitive electrochemical detection of Hg2+

A simple and sensitive electrochemical assay strategy of stripping voltammetry for mercury ions (Hg2+) detection is described based on the synergistic effect between ionic liquid functionalized graphene oxide (GO-IL) and gold nanoparticles (AuNPs). The AuNPs-GO-IL modified onto glassy carbon electrode (GCE) resulted in highly enhanced electron conductive nanostructured membrane and large electroactive surface area, which was excellently examined by scanning electron microscopy and cyclic voltammetry. After accumulating Hg2+, anodic stripping voltammetry (ASV) was performed, and differential pulse voltammetry (DPV) was employed for signal recording of Hg2+. Several main experimental parameters were optimized, i.e., deposition potential and time of AuNPs were -0.2 V and 180 s, respectively, and accumulation potential and time of Hg2+ were -0.3 V and 660 s, respectively. Under the optimal conditions, this AuNPs-GO-IL-GCE sensor attained a good linearity in a wide range of 0.1-100 nM (R = 0.9808) between the concentration of the Hg2+ standard and peak current. The limit of detection was estimated to be 0.03 nM at a signal-to-noise ratio of 3 sigma. A variety of common coexistent ions in water samples were investigated, showing no obvious interferences on the Hg2+ detection. The practical application of the proposed sensor has been carried out and demonstrated as feasible for determination of trace levels of Hg2+ in drinking and environmental water samples.