Preparation And Application Of Zinc Ferrite/Graphene Oxide Composite Aerogels For Electrochemical Detection Of P-nitrophenol

P-nitrophenol is a widely used and highly toxic chemical raw material.The indiscriminate discharge of industrial wastewater containing p-nitrophenol will destroy the ecological balance and cause harm to the body after being ingested by humans and animals.Therefore,the research on the development of rapid and sensitive detection technology for p-nitrophenol is of practical significance.This thesis takes graphene oxide aerogels as the starting precursor,combined with the features of spinel zinc ferrite nanoparticles such as high electrochemical activity,high porosity and specific surface area.This design is conducive to expanding the contact area between the electrode material and the reactant,increasing the active site of the electrocatalytic reaction,shortening the charge transfer path,improving the mass transfer performance of the electrode,and forming a highly efficient modified electrode catalytic material,so as to effectively carry out application of electrochemical analysis for the detection of p-nitrophenol.Based on the research of preparing mixed transition metal oxides?zinc ferrite?,further research on graphene-based aerogel materials was conducted.The aim is to construct an electrochemical sensor with high sensitivity and fast response to p-nitrophenol.This thesis designed three graphene-based aerogel modified electrode materials and the main work is as follows:?1?The"Benzyl Alcohol-Mediated"method was introduced into the preparation process of zinc ferrite nanoparticles?ZnFe₂O₄ NPs?,which makes them have the characteristics of controllable particle size and high crystallinity.Benzyl alcohol can act as an effective reducing agent and structure directing agent under solvothermal reaction.The gentle liquid phase route can control the nucleation and growth at the molecular level,the reaction pathway and the homogeneity,making ZnFe₂O₄ NPs have a well-defined size and uniform crystal morphology.The prepared small-diameter ZnFe₂O₄ NPs?12 nm?were grown on the surface of reduced graphene sheet in the hydrothermal process.Using ZnFe₂O₄/rGO as the electrode modification material for the detection of p-nitrophenol,the electrochemical sensing test of p-nitrophenol was carried out.The sensitivity reached 23.985 mA mM^-1 cm^-2 in the concentration range of 1?mol/L to 30?mol/L p-nitrophenol.The detection of p-nitrophenol with ZnFe₂O₄/rGO/GCE also has good reproducibility and detection performance for real water bodies.?2?Based on the studied"Benzyl Alcohol-Mediated"method for the preparation of highly crystalline ZnFe₂O₄ NPs,noble metal?Ag?were used for doping to improve the response of ZnFe₂O₄/rGO modified electrodes to p-NP.Ag with good catalytic properties is selected as a dopant to build a heterojunction between Ag-ZnFe₂O₄.The good affinity of Ag nanoparticles for reactant molecules can effectively accelerate electron transfer,assisted by graphene as the base material to disperse the nanopairs,and prevent their agglomeration from hindering the efficiency of electron conduction.The prepared Ag-ZnFe₂O₄/rGO composite material was used for p-nitrophenol electrochemical sensing test,and the results showed that it had a good electrochemical response.?3?Based on the above research,the graphene oxide-base material was modified by coupling polyaniline?PANI?,and the three-dimensional sandwich-like ZnFe₂O₄/PANI@rGO aerogel composite material was designed using graphene assisted self-assembly of ZnFe₂O₄ NPs and PANI@rGO nanosheets.The as-prepared ZnFe₂O₄/PANI@rGO aerogel not only benefits from the local electrical conductivity sandwiched between PANI and reduced graphene oxide?rGO?nanosheets or ZnFe₂O₄ nanoparticles dispersed on PANI@GO nanosheets,but also the long-distance conductivity from the“rGO bridges”among the aerogel framework.Using ZnFe₂O₄/PANI@rGO as an electrocatalyst modified electrode for the electrochemical sensing test of p-nitrophenol,the sensitivity reached 36.898 mA mM^-1 cm^-2 in the concentration range of p-nitrophenol from 1?mol/L to 20?mol/L.