Simultaneous determination of Cd2+ and Pb2+ by an electrochemical sensor based on Fe3O4/Bi2O3/C3N4 nanocomposites

The high adsorption capacity of Fe 3 O 4 and C 3 N 4 for heavy metals and the amalgam effect of Bi 2 O 3 were exploited using a Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 -modified glassy carbon electrode (GCE) for the determination of Cd 2+ and Pb 2+ . The electrochemical response performance of the Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 /GCE was studied by square-wave anodic stripping voltammetry. The electrochemical conditions were optimized, including the pH of the buffer solution, content of Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 on the electrode surface, deposition potential and deposition time. Under optimum conditions, the Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 /GCE sensor shows a linear response from 0.01 μmol/L to 3 μmol/L. The minimum detectable quantity for Cd 2+ and Pb 2+ are 3 × 10 −9  mol/L and 1 × 10 −9  mol/L, respectively. Interference studies were carried out. The sensitivity of the Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 /GCE sensor to Cd 2+ and Pb 2+ does not significantly change in the presence of coexisting heavy metal ions. The Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 /GCE sensor exhibits good stability and repeatability. The Fe 3 O 4 /Bi 2 O 3 /C 3 N 4 /GCE sensor was used to detect Cd 2+ and Pb 2+ in river water samples to demonstrate its real-world application.