Electrochemical Detection of Pb(II) Ions in Aqueous Solution by Carbon Nanospheres Modified Boron-Doped Diamond Electrode

In this paper, a sensor using carbon nanospheres modified boron-doped diamond (CNs/BDD) electrode for detecting heavy metal ions rapidly in aqueous solution is studied. The CNs/BDD electrode is characterized systematically by techniques including scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the CNs/BDD electrode, BDD electrode and Au electrode are compared by cyclic voltammetry. It is found that the CNs/BDD electrode has more negative hydrogen evolution potential, a wider potential window and a larger effective electrode area, which is conducive to the accurate detection of heavy metal ions. The square-wave anodic stripping voltammetry (SWASV) is applied to assess and quantify the sensing capability of the CNs/BDD electrode. The effects of deposition potential, deposition time and other experimental parameters on the detection performance are studied. Under the optimal experimental conditions, CNs/BDD electrodes exhibit remarkable detection capabilities for lead (Pb(II) ions, in which a linear relationship within the concentration range from 1 to 140 µg/L with a 0.9994 correlation coefficient is obtained. Meanwhile, it has excellent repeatability with a low relative standard deviation (RSD) of 0.57%, and the achieved actual limit of detection (LOD) reaches 0.01 µg/L. In addition, the interference experiment results show that except for Cd(II) ions and Cu(II) ions, other common ions in water have little interference to Pb(II) ion detection. The Pb(II) ions recovery rates are 89.1–115.7% in the real water samples. Experimental analysis indicates that the CNs/BDD electrode possesses the advantages of low detection limit, short detection time, and simple experimental equipment, which meets the requirements of Pb(II) ions field detection.