Nanoengineered Mn3O4/rGO electrophotocatalyst with dual functionality for detection of 2,4,6-trichlorophenol and degradation of methylene blue dye in environmental monitoring and cleanup

Abstract

Here, we report the hydrothermal synthesis of Mn₃O₄ nanomaterial and Mn₃O₄/rGO nanocomposite (rGO, reduced graphene oxide). The prepared nanocomposite (NC) was electrophoretically deposited (EPD) on indium tin oxide (ITO) to fabricate the Mn₃O₄/rGO/ITO electrode, which is further utilized for the electrochemical estimation of 2,4,6-trichlorophenol (2,4,6-TCP). The charge transfer rate constant, diffusion coefficient (D), and surface concentration values evaluated for the Mn₃O₄/rGO/ITO electrode are 0.53 s⁻¹, 0.86 × 10⁻⁶ mol cm⁻², and 0.358 cm² s⁻¹, respectively. The electrochemical sensor displays a linear extent of 2,4,6-TCP detection from 1 to 500 μM with a limit of detection (LoD) of 0.038 μM and sensitivity of 2.17 Ω μM⁻¹ cm⁻². Here, we demonstrate the 2,4,6-TCP detection via electrochemical impedance spectroscopy (EIS) sensing and photocatalytic degradation, as well as the kinetics of methylene blue (MB) dye, analyzed in parallel with bare Mn₃O₄ under UV light irradiation. The results indicate that Mn₃O₄/rGO NCs have preferred MB photodegradation efficacy with a reaction rate constant and low degradation time compared to bare Mn₃O₄ nanomaterials (NMs). The rate constants for the Mn₃O₄ and Mn₃O₄/rGO NCs were found to be 0.00075 and 0.0197, respectively, and the MB dye degradation reached up to 6% with the Mn₃O₄ catalyst and up to 80% with the Mn₃O₄/rGO catalyst when exposed to UV light for 80 minutes.