Highly selective and sensitive Pb2+ detection via sulfur-doped graphitic carbon nitride modified by Bi nanospheres

Abstract

The present-day human race is facing a series of environmental problems due to sewage discharge, excessive use of chemicals, mineral exploitation and so on, which are closely related to the rapid development of industries. The direct consequence is that the pollution of heavy metal ions is becoming more and more serious. It is very important to develop sensitive and efficient methods for detecting heavy metal ions. In this study, the nanocomposite of sulfur-doped graphitic carbon nitride (SCN) and Bi nanospheres (BiNSs) was prepared by thermal polycondensation reaction to introduce the sulfur into carbon nitride, followed by solvothermal method to realize the decoration of BiNSs. The SCN/BiNSs nanocomposite presents a highly selective and sensitive electrochemical detection capacity for Pb2+, derived from S-Pb strong bonding interaction and Bi-Pb binary alloy formation. The low detection limit of 0.07 μM could be achieved when the current response of Pb2+ was measured in the linear range of 0.1 μM − 4.5 μM by square wave anodic stripping voltammetry. The detection of Pb2+ in actual water specimens led to a recovery rate varied from 88 to 123 %. Further, in the presence of 20-fold interfering ions such as Zn2+, Fe3+, Cd2+, Cu2+, Fe2+ and Ni2+, the SCN/BiNSs-modified electrode still possesses excellent immunity and selectivity. Meanwhile, the remarkable stability, repeatability and reproducibility of the above sensing electrode have also been demonstrated. Our primary results show that the SCN/BiNSs nanocomposite holds great potential for practical application for Pb2+ detection.