An Optimized MnO2-Ag Nanocomposite-Based Sensing Platform for Determination of 4-nitrophenol in Tomato Samples: Influences of Morphological Aspect of MnO2 Nanostructures and Synergic Effect on Electrochemical Kinetic Parameters and Analytical Performance

Abstract

Abstract We have introduced potential modifiers synthesized from attached Ag nanoparticles (NPs) on MnO2 nanostructural surfaces, and fabricated an electrochemical sensor toward 4-nitrophenol (4-NP) detection. MnO2 with various morphologies (nanowires, nanorods, and nanosheets) has been prepared by hydrothermal and microwave-assisted hydrothermal methods, while AgNPs have been prepared by the simple electrochemical method. The structural characteristics and surface morphologies have been investigated via X-ray diffraction and scanning electron microscopy measurements. The effect of the change in morphology on the electrochemical behaviors and sensing performance has been investigated and discussed in detail. A parameter series involving the redox reaction of [Fe(CN)6]3-/4- and 4-NP reduction process has been calculated for each as-prepared modified electrode. Electrochemical results evidenced that benefiting from possessing outstanding electrochemical behaviors such as better conductivity, faster electron transfer ability, larger electroactive surface area, and higher charge transfer kinetics, MnO2 sheets-Ag/SPE has offered wider linear concentration range of 0.5-50 μM, LOD value as low as 0.073 µM, and high selectivity/repeatability. Furthermore, the optimization in the morphological aspect of MnO2 nanosheets and synergic effects arising from the effective combination with AgNPs make it become a model material for modifying electrode surfaces, indicating great potential for advanced electrochemical sensing applications.