A Study of Nanostructured FeO Thin Film-Based Allure Red and Direct Blue 15 Azo Dyes Sensing Scheme

This study reports on the amperometric sensing properties of FeO/Fe₂O₃ thin films for the detection of Allura Red (AR) and Direct Blue 15 (DB15) Azo dyes. The FeO/Fe₂O₃ thin films were produced using the Sequential Ionic Layer Adsorption and Reaction (SILAR) method and Na⁺-doping. The morphological and structural properties of the nanocomposites produced at pH of 10.5 showed good properties for the detection of azo dyes. The linear curve fit equations for AR and DB15 droplet applications onto Na⁺-doped FeO nanocomposite thin film samples were found to be y = -0.0002x + 0.0043 (R² = 0.9143) and y = -7E-05x + 0.0005 (R² = 0.9809), respectively. The findings reveal that adding Na⁺ doping to FeO/Fe₂O₃ thin films can effectively increase the detection response for the target azo dyes and enhance the sensitivity of the sensing system. The results suggest that the SILAR method can be used to produce low-cost and reusable FeO/Fe₂O₃ thin film devices, which can be promising candidates for the detection of toxic azo dyes in liquid samples.