Exploring the synchronized effect of MWCNT/X-manganate (X-Cu, Zn) nanocomposite for the sensitive and selective electrochemical detection of Hg(II) and Pb(II) in water

The presence of heavy metal ions in the environment is a long-lasting problem that requires the simultaneous detection of Hg(II) and Pb(II) which is both vital and challenging. This present study examines a simplified and effective approach for synthesizing multi-walled carbon nanotube–copper manganese oxide (MWCNT–CuMn₂O₄) and multi-walled carbon nanotube–zinc manganese oxide (MWCNT–ZnMn₂O₄) nanocomposites for electrochemical detection of heavy metal ions. The nanocomposites MWCNT–CuMn₂O₄ and MWCNT–ZnMn₂O₄ exceptional electrochemical performance was evaluated using Square Wave Anodic Stripping Voltammetry (SWASV). The fabricated MWCNT–ZnMn₂O₄ demonstrated lower values of Electrochemical Impedance Spectroscopy (EIS) with charge transfer resistance (R_ct) of approximately 34.13 Ω. Remarkably, the MWCNT–ZnMn₂O₄ electrochemical sensor exhibited the widest linear ranges of 0.5–10 μM with sensitive detection limits (0.011 μM for Hg(II) and 0.014 μM for Pb(II)). Interestingly, the MWCNT–ZnMn₂O₄ sensor showed excellent capability in detecting Hg(II) and Pb(II) in real water samples with a recovery percentage of 94.1% and 91.3%. Overall, the MWCNT–ZnMn₂O₄ modified GCE showcased superior selectivity, sensitivity, reproducibility, stability, and repeatability.