Hybrid nanostructures of Pd-WO3 grown on graphitic carbon nitride for trace level electrochemical detection of paraoxon-ethyl.

Well-defined crystal structures of Pd-doped WO3 nanorods were assembled on graphitic carbon sheets (Pd-WO3/g-C3N4) for ultrasensitive detection of paraoxon-ethyl (PEL) using an electrochemical method. The electrochemical behavior of PEL on the Pd-WO3/g-C3N4 hybrid composite was investigated using cyclic voltammetry (CV) and amperometric techniques. The Pd-WO3 crystallite was seen to modify the kinetics of g-C3N4, which improved the reduction/redox peak currents of PEL at the Pd-WO3/g-C3N4 composite compared to those of the g-C3N4 and WO3/g-C3N4-modified electrode. Moreover, the π-π interaction and hydrogen bond between the PEL and Pd-WO3/g-C3N4 composite improved the charge-transfer properties. The Pd-WO3/g-C3N4 hybrid composite was therefore able to obtain an enhanced sensitivity (3.70 ± 0.05 μA μM-1 cm-2) and low detection limit (0.03 nM; S/N = 3) with a wide range of linear concentrations (0.01-60 and 80-900.0 ± 5 μM) at applied potential of - 0.63 V (vs. Ag/AgCl). The detection of PEL in agricultural water and soil samples was successfully demonstrated with satisfactory RSD of 2.5 to 3.1% and recovery results of 97 to 102%, respectively.