Preparation Of Enzyme-free Horseradish Peroxidase Sensor By Two-dimensional Metal Hydroxide Composite

This dissertation focuses on the preparation of two-dimensional NiAl hydroxide-polypyrrole-silver(LDH-PPy-Ag)composites and two-dimensional NiAl oxide-polypyrrole-silver(LDO-PPy-Ag)composites.The modified electrodes LDH-PPy-Ag/GCE and LDO-PPy-Ag/GCE were prepared by modifying composites on the electrode surface to construct H2O2 sensor with excellent performance.The specific research work is as follows:NiAl LDH with a Ni/Al molar ratio of 3:1 was prepared by the urea method and was compounded with different amounts of polypyrrole to obtain a NiAl hydroxide-polypyrrole composites(LDH-PPy).The composites were characterized by XRD,FT-IR,SEM and TG/DTG.The results showed that polypyrrole was coated on the surface of hydrotalcite.By electrochemical means CV and EIS analysis,it was found that NiAl LDH and PPy played a synergistic role.Compared to a single material,the composite material greatly improved the electrochemical performance in phosphate buffer(PBS)at pH=7.0.LDH-PPy0.7 has the best electrochemical performance.LDH-PPy0.7-Ag composites were successfully prepared and used for electrode modification to construct an enzyme-free H2O2 sensor.The silver nanoparticles were evenly dispersed on the surface of the LDH-PPy material without agglomeration.By EIS analysis,LDH-PPy0.7-Ag composites have a smaller electrochemical impedance than LDH-PPy.Silver nanoparticles increase the electronic conductivity and catalytic properties of the material.The prepared enzyme-free H2O2 sensor has a linear detection range of 3.0×10-5?8.0×10-3 mol/L for H2O2,a sensitivity of 257.64?A/(mmol·cm-2),and a detection limit of 2.O×10-5 mol/L(S/N=3).NiAl LDH with a Ni/Al molar ratio of 3:1 was prepared by the urea method,and then LDH was calcined at 400?.to obtain a calcined NiAl double metal oxide(LDO),which was then compounded with different amounts of polypyrrole.NiAl oxide-polypyrrole composite(LDO-PPy)was obtained.LDO-PPy was analyzed by various characterization methods.It was found that polypyrrole was coated on the surface of LDO.By CV and EIS analysis,LDO-PPy compared to a single material,the electrochemical performance of the composite material in PBS pH=7.0 was improved,and the electrochemical performance of LDO-PPy0.9 was the best.LDO-PPy0.9-Ag composites were successfully prepared and used to modify electrodes to construct an enzyme-free H2O2 sensor.Silver nanoparticles were evenly dispersed on the surface of LDO-PPy0.9 material,and no agglomeration occurred.The prepared non-enzymatic H2O2 sensor has a linear detection range of 1.0×10-5?8.O×10-3 mol/L for H2O2,a sensitivity of 346.50 ?A/(mmol·cm-2),and a detection limit of 0.5×10-5 mol/L(S/N=3),and the preparation method is simple and has good anti-interference performance.