Deep eutectic solvent-driven synthesis of La2NiO4@rGO Ruddlesden–Popper hybrids for ethyl parathion sensing supported with theoretical studies

Abstract

In this work, Ruddlesden–Popper phase perovskite La₂NiO₄ was synthesized via a hydrothermal method employing a deep eutectic solvent as the reaction medium. Benefiting from its pronounced faradaic activity, La₂NiO₄ served as the primary electroactive component for sensing studies. To further enhance electron transport and increase the density of accessible active sites, a hybrid heterostructure La₂NiO₄@rGO was made through a versatile sonochemical method. This synergistic architecture markedly enhanced the electrochemical charge-transfer kinetics and sensing performance toward ethyl parathion (EP). This La₂NiO₄@rGO-modified glassy carbon electrode delivered a broad linear detection range of 0.05–1625 µM for the electrochemical reduction of EP, with a lower limit of detection of 18 nM. Density functional theory (DFT) calculations provided additional molecular-level insight, revealing an ionization potential of 6.86 eV and an electron affinity of 2.37 eV for EP based on frontier orbital analysis. The La₂NiO₄@rGO/GCE sensor further exhibited excellent sensitivity, stability, selectivity, repeatability, and reproducibility, confirming its suitability for real-sample analysis. Overall, the La₂NiO₄@rGO/GCE platform offers a promising strategy for rapid and reliable EP detection, demonstrating its strong potential for advanced food-safety monitoring applications.