Fabrication And Electrochemical Detection Of H₂O₂ Of Graphene Quantum Dots And TiO₂ Nanotube Modified Electrode

H2O2 is not only widely used in the chemical,pharmaceutical,printing and dyeing,cosmetics and food industries as an important industrial raw material,but also one of the most important active molecules in the process of life.Studies have shown that H2O2 can damage human cells after it enters the body,severely affecting cell function and metabolism,and high concentrations of H2O2 can even cause cell death.In recent years,China has attached great importance to the production of fine chemical products,especially to the development of new hydrogen peroxide products,which has led to an increase in consumption in the chemical industry.It has also been used in food,chemical bleaching,papermaking,and electronics industries.Hydrogen peroxide detection is of great significance.The detection of H2O2 by electrochemical sensor method has the advantages of rapid response,high sensitivity and simple method,so it has been widely used.Graphene quantum dots(GQDs)are a new type of graphene-based carbon nanomaterials.Due to their large surface area,high electron mobility,excellent photoluminescence,and biocompatibility,GQDs have great potential in the construction of electrochemical sensors and fluorescent sensors.Citric acid was used as raw material to prepare GQDs by pyrolysis.GQDs were characterized by UV-vis and fluorescence spectra.The maximum excitation wavelength of GQDs was 305 nm.After H2O2 was added,the fluorescence intensity of GQDs dropped sharply to 13%.The linear equation fitting the fluorescence intensity of GQDs and the concentration of H2O2 is F=-55.9446 C + 117.8598.The fluorescence quenching degree shows a linear relationship with the concentration of H2O2.The linear equation is F0/F=-0.40428 C + 0.91226,and the linear range is 0.5~2 mmol/L.A GQDs modified electrode was prepared and used as an electrochemical sensor to detect the electrochemical behavior of H2O2 in different concentrations of PBS at a concentration of 1~10 mmol/L of H2O2,which shows a good linear relationship.The equation for the linear fitting of the current response to the concentration of H2O2 at-0.6 V is I =-8.6572-13.6905 C.Experiments show that GQDs have good electrocatalytic reduction performance for H2O2.Ti O2 nanotubes have become a very important inorganic functional material because of their unique electrocatalytic and photocatalytic properties.In particular,they have made outstanding contributions in the fields of sensors and catalyst carriers.The anodic oxidation method was used to prepare Ti O2 nanotubes.Scanning electron microscope images of Ti O2 nanotubes showed that the average tube inner diameter of the oxidized nanotube array was about 100 nm,the thickness was about 15 nm,and the length was about 210 nm.Electrochemically modified graphene-modified primary oxidized Ti O2 nanotubes showed an obvious reduction peak at-0.35 V.Compared with the primary oxidation of Ti O2 nanotubes,whose current changes,the secondary oxidation of Ti O2 nanotubes whose reduction peak appeared at-0.4 V,and the graphene-modified secondary Ti O2 nanotubes who showed a reduction peak at-0.36 V,the graphene-modified primary Ti O2 nanotubes had a more positive reduction potential.The conductivity was optimal in the four electrodes.Electrochemical detection of H2O2 showed that the currents of the four electrodes in the range of 0.1~10 mmol/L showed a linear relationship with the concentration of H2O2.Graphenemodified primary oxidized Ti O2 nanotubes showed higher catalytic activity than other electrodes.The detection limit of it was 3.84?10-3 mol/L,and the sensitivity was 30.49 m A·(mmol·L-1)-1.Ti O2 nanotubes are modified to improve the electrochemical performance and stability of them.Polyaniline and silver nanoparticles modified primary oxidized Ti O2 nanotubes electrodes were prepared by the electrochemical method.Scanning electron microscopy of the electrode material show that polyaniline is clustered and metallic silver is in granular on Ti O2 nanotubes.H2O2 was electrochemically detected on the modified Ti O2 nanotube electrode.Compared with the reduction potential of-0.35 V on polyaniline modified primary oxidized Ti O2 nanotubes electrodes,the reduction potential on the first oxidized Ti O2 nanotubes electrode modified by silver nanoparticles was-0.25 V,whose peak potential shifted positively,indicating that the silver nanoparticles modified electrode has good electrocatalytic properties.The detection of H2O2 by two modified electrodes showed good linearity in the range of 0.5~10 mmol/L.The detection limit of polyaniline modified electrode was 4.38?10-3 mol/L,and the sensitivity was 19.9 m A·(mmol·L-1)-1,the detection limit of the nano-silver modified electrode was 3.05?10-3 mol/L,and the sensitivity was 22.48 m A·(mmol·L-1)-1.The silvermodified electrode shows better catalytic performance and higher sensitivity.