Organophosphorus Pesticide Photoelectrochemical/Electrochemical Dual-Mode Smartsensors Derived from Synergistic Co,N-TiO2@ZrO2/3DGH Platform

Organophosphorus pesticides (OPs), while pivotal for agricultural productivity, pose severe environmental and health risks due to their persistence and bioaccumulation. Existing detection methods, such as chromatography and spectroscopy, face limitations in field adaptability, cost, and operational complexity. To address these challenges, this study introduces a novel dual-mode photoelectrochemical–electrochemical (PEC-EC) sensor based on a Co,N-TiO2@ZrO2/3DGH nanocomposite. The sensor synergistically integrates zirconium oxide (ZrO2) for selective OP capture via phosphate-Zr coordination, cobalt-nitrogen co-doped titanium dioxide (Co,N-TiO2) for visible-light responsiveness, and a three-dimensional graphene hydrogel (3DGH) for enhanced conductivity. In the PEC mode under light irradiation, OP adsorption induces charge recombination, yielding a logarithmic photocurrent attenuation with a detection limit of 0.058 ng mL−1. Subsequently, the EC mode via square wave voltammetry (SWV) self-validates the results, achieving a detection limit of 0.716 ng mL−1. The dual-mode system demonstrates exceptional reproducibility, long-term stability, and selectivity against common interferents. Parallel measurements revealed <5% inter-mode discrepancy, validating the intrinsic self-checking capability. This portable platform bridges the gap between laboratory-grade accuracy and field-deployable simplicity, offering transformative potential for environmental monitoring and food safety management.