Nanocomposite matrix based on gerhardtite-type copper (II) hydroxy nitrate and ZnO/CeO2 nanoparticles - a sensitive platform for aminomethylphosphonic acid detection

In this research, an electrochemical platform based on a gerhardtite-type copper (II) hydroxy nitrate (i.e., (Cu 2 (OH) 3 NO 3 , Cu_hn), zinc oxide-decorated cerium oxide nanoparticles (ZnO-CeO 2 NPs) was constructed for the first time. Gerhardtite-type Cu_hn and ZnO-CeO 2 NPs were produced by green synthesis using plant extracts, thus ensuring the sustainability of the proposed technology. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-angle annular dark-field image (HAADF), energy-dispersive X-ray spectrometry (EDS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) were used for morpho-structural characterisation. Then, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were used to study the modified electrode (i.e., Chit(Cu_hn+ZnO-CeO 2 NPs)/GCE) in the presence of aminomethylphosphonic acid (AMPA). The developed electrode has a lower detection limit (640 ± 1.18 nM) and a sensitivity of 0.16 µA∙µM −1 (i.e., 35.55 µA∙µM −1 ∙cm −2 ) in a linear concentration range of 1.25 to 8.75 µM AMPA. Besides, it reported long-term stability (up to 28 days), high reproducibility, and excellent selectivity in the presence of other pesticides, metals, and pharmaceutical interferents. Furthermore, this modified electrode can also be applied to the detection of AMPA in groundwater, with a recovery of 101.53%. It is worth mentioning that the developed Chit(Cu_hn+ZnO-CeO 2 NPs)/GCE-based modified electrode has enormous potential application in favourable, easy, cheap, and selective detection of AMPA in environmental samples without any sample preparation.