Exploitation of MnCo2O4@g-C3N4-Derived Electrochemical Sensing Platform for Individual Determination of Pb2+ Ions and Chloramphenicol (CAP) with Excellent Analytical Performance

Abstract

In this study, MnCo2O4 is successfully synthesized via a one-pot microwave-assisted hydrothermal method and uniformly integrated into the g-C3N4 framework. The resulting MnCo2O4@g-C3N4 composites are designed for the sensitive and selective detection of the antibiotic CAP and toxic Pb2+ heavy metal ions in aqueous media, respectively. Structural and surface characteristics of the materials are analyzed using spectroscopic techniques, confirming their superior physicochemical properties, particularly those of the MnCo2O4@g-C3N4 composites. The MnCo2O4@g-C3N4/SPE demonstrates enhanced electrochemical characteristics, including lower charge-transfer resistance (Rct = 1688 Ω and ∆Ep = 190 mV), a larger electrochemically active surface area (0.1708 cm2), and increased density of surface-active sites. Electrochemical sensing studies reveal efficient cathodic reduction of CAP and anodic oxidation of Pb2+ at MnCo2O4@g-C3N4-based sensor. The as-developed sensor exhibits favorable electron-transfer kinetics toward the redox processes of both analytes, corresponding to the following regression equations: Ipc (μA) = 0.006ν (mV s-1) + 1.529 (R2=0.997) for CAP and Ipa (μA) = 3.16ν1/2 (mV s-1)1/2 - 2.045 (R2=0.998) for Pb2+. It achieves wide linear detection ranges (0.25-50 μM for CAP, 0.5-1000 ppb for Pb2+), low LOD of 0.2 μM for CAP and 1.07 ppb for Pb2+), and high sensitivities (1.3 μA•μM-1•cm-2 for CAP, 0.24 μA•ppb-1•cm-2 for Pb2+).