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

[Display omitted] • Sm-BDC is the first Ln-BDC MOF sustainably prepared. • Ternary CdS-SmBDC-g-C 3 N 4 composite shows synergic interactions between its components. • Composite-modified electrodes are excellent to oxidize/detect malathion. • The sensitivity was as high as 25 μAμM−1 with detection limit of 7.4 × 10−9 M. 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-C 3 N 4 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-C 3 N 4 -5 wt% modified electrode exhibited higher peak current than the bare GCE, with excellent electrocatalytic ability to oxidize malathion, due to its higher conductivity, catalytic effect and synergistic effects between CdS, g-C 3 N 4 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 that modifying electrode surfaces with novel composites can enhance the detection of organophosphate pesticide. [ABSTRACT FROM AUTHOR]