Non-enzymatic detection of methyl parathion in water using CeO₂-CuO-decorated reduced graphene oxide

The widespread use of organophosphorus pesticides (OPS) poses important challenges to the environment and human health, which renders the detection of OPS with fast, accurate, and sensitive methods essential. Herein, high-performance non-enzymatic methyl parathion (MP) sensors were developed by exploiting the unique physicochemical properties of reduced graphene oxide (rGO) and high susceptibility of CeO₂-CuO-based mixed metal oxide nanoparticles to MP, for the first time. Furthermore, we also showed that the analytical performance of CeO₂-CuO systems can be tuned by changing the atomic ratios of Ce/Cu to achieve high-performance electrochemical MP sensors. In this regard, the rGO surface was modified with CeO₂-CuO solid solutions with (3:1), (1:1), and (1:3) molar ratios. The equimolar mixed metal oxide composition yielded a significant enhancement in the sensor response compared to CeO₂-rich and CuO-rich counterparts. The CeO₂-CuO/rGO (1:1)-based sensors showed a linear range of 1–40 ppb and a very low LOD of 0.47 ppb. Besides displaying a high selectivity towards common interfering agents, the sensors showed high long-term stability and acceptable applicability to real samples for MP detection. Therefore, our results suggest that non-enzymatic electrochemical MP sensors with very low LOD can be designed by engineering the structure of metal oxide nanoparticles.