Glyphosate Detection via Defect Engineering on NiAl Layered Double Hydroxides

On-site detection of herbicides is imperative to ensure food safety; thus, effective electrochemical sensors are required. In this study, electrochemical detection of glyphosate and glufosinate was achieved through the rational design of a defect-engineered transductor based on surface-defective NiAl layered double hydroxides supported on a N-doped carbonaceous support. The NiAl atomic composition was optimized, and the 3:1 ratio exhibited the best performance. In phosphate buffer solution (0.1 M PBS pH 11), this material presented a sensitivity of 276 mA M–1 cm–2 and a limit of detection (LOD) of 0.43 μM (as determined by cyclic voltammetry). The LOD was enhanced to 0.081 μM using differential pulse voltammetry. An electrochemical solid-state sensor for on-site tests was developed using screen-printed electrodes and hydrated poly(vinyl alcohol) membranes. The solid-state prototype was tested under laboratory conditions by spraying glyphosate onto a plant, and the electrochemical results demonstrated good repeatability and stability. The excellent detection performance of the sensor was attributed to the induced surface defects and the major center of Ni exposure, as determined by chemical calculations, where the induced defects enabled changes in the surface electrical properties of the layered double hydroxide (LDH).