ZnO-CNT/Nano-Au modified electrodes for the detection of trace Hg(II) in coastal seawater

Abstract

Mercury (Hg) in seawater enters the body through the food chain, causing damage to organs and the nervous system. Thus, there is an urgent need to explore a rapid and convenient sensor for the detection and monitoring of Hg(II) in seawater. Herein, a ZnO-CNTs/Nano-Au modified glassy carbon electrode was prepared by the dropping method. The structure of the composite membrane is mainly observed by scanning electron microscopy (SEM), and the results show that the composite has a larger specific surface area. Moreover, the composite can increase the ion adsorption of the surface electrode and enhance the conductivity. Differential pulse voltammetry (DPV) was applied to determine trace amounts of Hg(II) in seawater. The optimized conditions were as follows: accumulation potential, accumulation time, pH value, film thickness and concentration. Under the optimal experimental conditions, the linear relationship between the values of the oxidation peak current and concentration was kept in the range of 1.49~5.97 μM, with a linear correlation coefficient R2=0.97443 and a detection limit of Hg(II) of 0.0156 μM. The proposed method was applied to the analysis of coastal water of the Maowei Sea, giving values of recovery in the range of 94.2%~98.4%. The ZnO-CNTs/Nano-Au-modified electrode has high sensitivity, convenient operation and good practical application value.