The Preparation Of Nanomaterials With Montmorillonite As Carrier And Study Of Its Performance As Peroxidase Mimics

The development of nanomaterials has never stopped.It plays an increasingly important role in batteries,supercapacitors,sensors,catalysts and so on.In the past decade,nanomaterials have been found to possess the performance of peroxidase mimics,and can be well used in the field of hydrogen peroxide detection.Although the natural enzymes have high catalytic activity and selectivity in the detection field of hydrogen peroxide,it has some disadvantages,such as poor stability,low temperature tolerance,low acid and alkali resistance,difficulty in preparation and storage,and so on.In spite of its low cost,good stability and high catalytic activity,nanomaterials also have some limitations in practical application because of their high specific surface energy and easy agglomeration.In order to improve the catalytic performance of nanomaterials as peroxidase mimics,montmorillonite(MMT)was used as good support with large specific surface area and stronge adsorption property,which could prevent the aggregation of nanomaterials.Montmorillonite supported iron oxides nanocomposites(Fe3O4-MMT)and cobalt doped nickel sulfide nanocomposites(Co-Ni-S-3/MMT)were prepared by simple hydrothermal method.It was also found that the nanocomposites possessed the excellent peroxidase-like activity and was used for the detection of hydrogen peroxide(H2O2).The main work of this thesis is as follows:1.Fe3O4 nanoparticles loaded on the surface of montmorillonite was prepared by ahydrothermal method.In the presence of hydrogen peroxide,Fe3O4-MMT nanocomposites were able to catalytically oxidize the reactive substrates(3,3',5,5'-Tetramethyl benzidine)(TMB)to blue oxidation product(oxTMB).The nanocomposite exhibited higher peroxidase activity than that of the MMT or Fe3O4 nanoparticles alone.The effects of pH and temperature on the activity of the peroxidase mimic were discussed.Moreover,it was found from the kinetic experiments that the catalytic reaction of this material as a peroxidase mimic was in good agreement with the kinetics of Michaelis-Menten,and showed good affinity to both H2O2 and TMB.Based on these experimental results,we have constructed a convenient and efficient colorimetric sensor for H2O2 detection.The linear response range is 50-200 ?M and the detection limit is as low as 5.1 ?M.It has been successfully applied to the determination of H2O2 residue in contact lens solution.2.Ternary transition metal sulfide nanomaterials deposited on the surface of MMT(Co-Ni-S-3/MMT)were prepared by a simple hydrothermal method and the nanocomposites were characterized by X-ray powder diffraction(XRD),transmission electron microscopy(TEM)and so on.The experimental results show that in the presence of H2O2,the nanocomposites can rapidly catalyze the oxidation of TMB to oxTMB only in 3 min,exhibiting a good peroxidase activity.In addition,the influences of Co2+ doping on the peroxidase activity of NiS nanoparticles supported on MMT were investigated by changing the amount of Co2+doping.MMT supported ternary transition metal sulfide nanocomposites(Co-Ni-S-3/MMT)exhibited a higher peroxidase activity than that of binary transition metal sulfide nanocomposites(Co-S/MMT or Ni-S/MMT).Similar to natural enzymes,Co-Ni-S-3/MMT act as a peroxidase mimics,and its catalytic reaction mechanism follows the Michaelis-Menten equation,and it also has good affinity to H2O2 and TMB.Based on the peroxidase activity of the nanocomposite,we constructed a convenient and efficient colorimetric sensor for H2O2 detection.The linear response range is 3-100 ?m,and the detection limit is as low as 1.5 ?M.The detection of H2O2 residue in contact lens solution is also feasible.