Herein, a new and generic strategy has been proposed to introduce uniformly distributed graphitic carbon into the nanostructured metal oxide. A facile and generic synthetic protocol has been proposed to introduce uniformly distributed conducting graphitic carbon into the Co3O4 nanoparticles ( Co3O4 NPs@graphitic carbon). The prepared Co3O4 NPs@graphitic carbon has been drop casted onto the portable screen-printed electrode (SPE) to realize its potential application in the individual and simultaneous quantification of toxic Pb(II) and Cd(II) ions present in aqueous solution. The proposed Co3O4 NPs@graphitic carbon-based electrochemical sensor exhibits a wide linear range from 0 to 120 ppb with limit of detection of 3.2 and 3.5 ppb towards the simultaneous detection of Pb(II) and Cd(II), which falls well below threshold limit prescribed by WHO.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Preparation of electrocatalyst
        2.2 Fabrication of Co3O4 nanoparticles@graphitic carbon modified SPE
        2.3 Electrocatalyst characterization
        2.4 Electrochemical performance measurements
    3 Results and discussion
        3.1 Structural and morphological studies
        3.2 Electrochemical impedance spectroscopy
        3.3 Cyclic voltammetry study
        3.4 Optimization study
        3.5 Effect of pH
        3.6 Effect of deposition potential
        3.7 Effect of deposition time
        3.8 Individual determination of Pb(II) and Cd(II)
        3.9 Simultaneous determination of Pb(II) and Cd(II)
        3.10 Stability and repeatability of the proposed sensor
        3.11 Interference study
        3.12 Application study
    4 Conclusions
    Acknowledgements 
    References

• R. T. Yogeeshwari(Department of Chemistry, M. S. Ramaiah Institute of Technology, Affiliated to Visvesvaraya Technological University, Department of Chemistry, Seshadripuram College)
• R. Hari Krishna(Department of Chemistry, M. S. Ramaiah Institute of Technology, Affiliated to Visvesvaraya Technological University)
• Prashanth S. Adarakatti(Department of Chemistry, SVM Arts, Science and Commerce College)
• S. Ashoka(Department of Chemistry, School of Engineering, Dayananda Sagar University)