CdS/g-C3N4/Sm-BDC MOF nanocomposite modified glassy carbon electrodes as a highly sensitive electrochemical sensor for malathion

Malathion is an organophosphate pesticide widely used in agriculture, whose elimination is highly demanded by society. This work faces this challenge by the development of a novel electrochemical sensor via modifying a glassy carbon electrode (GCE) with sustainable Sm-BDC MOFs and their corresponding novel binary and ternary composites combined with CdS and g-C3N4 for the detection of malathion. Different characterization techniques indicate the successful synthesis of desired composite materials, with notable interaction between the individual components. CdS-Sm-BDC-g-C3N4-5wt% modified electrode exhibited higher peak current than the bare GCE, with excellent electrocatalytic ability to oxidize malathion, due to higher conductivity, catalytic effect and synergistic effects between CdS, g-C3N4 and Sm-BDC. Under optimized condition, differential pulse voltammograms (DPV) demonstrate that the oxidation peak current was proportional to its concentration in the range of 3.0·10-8 - 15.0·10-8 M (R2 = 0.996), with high sensitivity (25 μAμM-1) and low detection limit (7.4·10-9 M or 7.4 μmM). In addition, the modified electrode affirms good stability and reproducibility, making it simple, cost effective with high sensitivity and selectivity. The results confirmed that making a composite is a key strategy for improving the physicochemical properties of MOFs and modifying electrode surfaces with novel composites enhanced the detection of organophosphate pesticide.