Zirconia nanocomposites with carbon and iron() oxide for voltammetric detection of sub-nanomolar levels of methyl parathion

This study reports the synthesis of zirconia nanoparticles loaded on various carbon substrates, namely, reduced graphene oxide (Zr-r-GO), carbon nanotubes (Zr-CNT), and activated carbon (Zr-AC). In addition, a composite of zirconia-iron mixed oxide loaded on activated carbon (FeZr-AC) was also synthesized. The materials were characterized using SEM-EDX, HRTEM, FTIR, Raman spectroscopy, TGA and XRD. The FeZr-AC sample was found to have a nanorod like morphology. The samples were evaluated for their sensing potential towards methyl parathion (MP) using differential pulse voltammetry in a range of 0.0 V to −0.9 V ( vs. Ag/AgCl) by drop casting on a glassy carbon electrode (GCE). All the modified GCEs best operated at a working potential of 0.4-0.9 V vs. Ag/AgCl/Cl − . FeZr-AC was found have the best limit of detection followed by Zr-AC, Zr-CNT and Zr-r-GO with their detection limits being 1.7 × 10 −9 M, 17.2 ×10 −9 M, 243.3 × 10 −9 M and 534.0 × 10 −9 M respectively. These materials were then used to detect MP in spiked sewage samples and showed good recoveries. This study reports the synthesis of zirconia nanoparticles loaded on various carbon substrates, namely, reduced graphene oxide (Zr-r-GO), carbon nanotubes (Zr-CNT), and activated carbon (Zr-AC).