Preparation Of Iron Oxide Nanocomposite And Poly-L-tyrosine Modified Electrode And Its Application In Electroanalytical Chemistry

The iron oxide nanocomposite is a novel multifunctional material that combines the physical and chemical properties of iron oxide with the properties of other nanomaterials and is widely used in electrochemical analysis.According to reports,iron oxide is oft en combined with other metals or metal oxides,carbon materials,etc.to form nanocomposites to modify the electrode,greatly improving the electrochemical performance of the working electrode.The complexes mentioned here also play an important role in modifying the electrodes.A new type of sensor was prepared by modifying the glassy carbon electrode with the prepared material,and the electrochemical performance of these sensors for the detection of nitrite was studied.The specific work is as follows:The palladium/iron oxide(Pd/Fe2O3)nanocomposites were prepared by electrochemical deposition and hydrothermal method and used to modify glassy carbon electrodes(GCE).Using energy dispersive X-ray spectroscopy(EDX)and transmission electron microscopy(TEM)and other characterization methods to determine the morphology and composition of the complex.Compared with the pure Fe2O3,PdNPs modified electrode and bare electrode,the prepared Pd/Fe2O3 composite modified electrode has enhanced electrocatalytic activity for nitrite catalyzed oxidation.The effects of Pd nanoparticles deposition and pH on the electrochemical performance of Pd/Fe2O3 modified electrode were studied.Under optimal conditions,Pd/Fe2O3-modified GCE can be used to detect nitrite concentrations in a wide linear range of 10 to 1000 u M with a detection limit of 0.1 ? M.The Pd/Fe2O3 modified electrode has strong anti-interference to Cu2+,Na+,Cl-,PO43-,SO42-,Mg2+,K+,NO3-and NH4+ ions when used to detect nitrite.At the same time,the Pd/Fe2O3 modified electrode also has good stability.A novel Fe2O3/MWCNTs/GCE modified electrode was prepared by hydrothermal co-precipitation to synthesize iron oxide/multi-walled carbon nanotubes(Fe2O3/MWCNTs)composites and coating them on the surface of GCE.The composites were characterized by scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)techniques to determine their morphology and chemical composition.Cyclic voltammetry(CV)results showed that the modified GCE of Fe2O3/MWCNTs complex had excellent electrochemical activity compared to pure Fe2O3 and MWCNTs modified electrodes in 0.1 M buffer containing 1 mM nitrite..Differential pulse voltammetry(DPV)results also show that Fe2O3/MWCNTs modified electrodes have excellent electrocatalytic properties for nitrite in a buffer solution of pH 7.0.The detection limit of the electrode was studied by chronoamperometry.The results showed that the Fe2O3/MWCNTs/GCE electrode can be used to detect nitrite concentrations within a wide linear rang of 10 to 1000 a M.The linear correlation coefficient R is 0.9988 and the detection limit is 0.1 ?M..A novel chemical sensor NiO/Fe2O3/GCE was prepared by depositing NiO nanomaterials onto a glassy carbon electrode loaded with iron oxide by electrochemical deposition in a nickel nitrate aqueous solution.The morphology and composition of NiO/Fe2O3 nanocomposites were determined by scanning transmission electron microscopy(STEM)and energy dispersive X-ray spectroscopy(EDX).The electrochemical properties of NiO/Fe2O3/GCE were studied using chronoamperometry(CA)and differential pulse voltammetry(DPV).Compared with the pure Fe2O3 or NiO modified electrode,the NiO/Fe2O3 composite modified GCE has the best electrochemical performance.The current response results showed that the NiO/Fe2O3 modified electrode can be used to detect 5-500 ?M wide linear range(R = 0.999)nitrite concentration with a detection limit of 0.05 ?M.In addition,the NiO/Fe2O3/GCE modified electrode has good selectivity and stability and is expected to be used in practical production.Poly(L-tyrosine)was deposited on the surface of GCE by electrochemical deposition to prepare a PLT/GCE sensor.Chronoamperometry(CA)and differential pulse voltammetry(DPV)were used to study the electrochemical performance of PLT/GCE modified electrode for the detection of nitrite ions.Poly-L-tyrosine-modified GCE exhibited enhanced nitrite anodes.signal.The influence of key parameters such as the pH of the solution,the number of deposition cycles and the scanning rate on the detection of nitrite by the modified electrode was also studied.Under optimal conditions,the chemically modified electrode can detect nitrite in the concentration range of 10 to 1000 u M with a detection limit of 0.08 uM and a correlation coefficient of 0.999.Using PLT/GCE modified electrode to detect nitrite is not affected by common ions such as Cu2+,Na+,Cl-,PO43-,SO42-,Mg2+,K+,NO3-and NH4+,and has strong anti-interference performance.Good stability.The PLT/GCE electrode is used to detect nitrite in tap water and has a good effect.It is expected to be used in actual production.