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A novel electrochemical sensor was constructed based on modification of polyaniline (PANI) and graphitic-phase carbon nitride (g-C 3 N 4) composites. Detection of Cd(II) ions in the aqueous environment using differential pulsed anodic stripping voltammetry (DPASV) technique. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), contact angle (CA), and Tafel curve analyses were used to characterize the physical and electrochemical properties of electrode. We prepared a new PANI@g-C 3 N 4 composite material by combining the two substances based on their respective advantages. The composite material was applied to electrode detection for the first time, which significantly enhanced the transfer of free electrons on the surface of the electrode, improved the sensitivity of the electrode, increased the adsorption capacity of Cd ions, and significantly improved the detection effect of the electrode. Parameters such as the amount of PANI@g-C 3 N 4 modification, deposition potential, deposition time and solution pH were optimized to determine the best conditions for the detection of Cd(II) ions. Under optimal conditions, our sensor achieves a best signal at −0.78 V (vs. Ag/Agcl electrode), and exhibits a wide linear concentration range of 0.1–140 μg/L with a low detection limit of 0.05 μg/L. The sensor was successful in implementing the identification of real water samples with recoveries ranging from 91 % to 106 %. The relative standard deviation (RSD) is less than 4.31 %. Besides, the sensor has outstanding anti-interference, repeatability and steadiness. The successful application of this sensor provides a new idea for efficient detection of Cd(II) ions in aquatic environments. [Display omitted] • PANI and g-C 3 N 4 composites were firstly used to modify GCE for Cd(II) detection. • The composite improves the electrode conductivity and Cd adsorption performance. • The PANI@g-C 3 N 4 @GCE shows a low Cd detection limit with wide linear range. • This sensor was also applied to the detection of Cd(II) ions in real water samples [ABSTRACT FROM AUTHOR]

Since lead is teratogenic, carcinogenic and mutagenic, people pay increasing attention to lead contamination in water environment. In this work, a novel electrochemical sensor was developed to detect Pb(II) ion in water by PPy, MOFs and bismuth film (BF) modify GCE. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, contact angleanalyses, cyclic voltammetry and differential pulse anodic stripping voltammetry were used to characterize the BF-PPy/UIO-66-NH 2 /GCE surface, revealing the physical and electrochemical properties of the electrode. MOFs increased the specific surface area and adsorption site of the electrode. The PPy enhanced the conductivity of the composites materials. MOFs and PPy synergistically promoted the electrochemical performance of the electrode. The deposition potential, deposition time, solution pH and Bi (III) concentration were optimized to determine the optimal detection condition. The electrode has a wide linear range (0.5 to 10 μg/L) with a low detection limit (0.05 μg/L). This electrode also has good anti-interference, repeatability and stability. Besides, it has been successfully applied to the detection of actual water samples. The recovery rates ranged from 95.4 % to 102.8 % with a relative standard deviation (RSD) less than 4.40 %. Our results provide an insight on efficient and rapid detection of Pb(II) ions in water environment in the future. [Display omitted] • MOFs and polypyrrole synergistically promoted the electrochemical performance. • The fabricated BF-PPy/UIO-66-NH 2 /GCE shows a low Pb(II) detection limit. • This sensor was applied to the detection of Pb(II) in tap water and groundwater. [ABSTRACT FROM AUTHOR]