Preparation And Properties Of Aminated Graphene-Modified Titanium Dioxide Catalysts

The defects of wide band gap energy and high carrier recombination rate have limited the application of Ti O₂,using modified materials to improve its performance has been comprehensively reported.Studies have shown that the way such as doping with precious metals,N-doping,C-doping and MOF can improve the quantum utilization efficiency and make the light response range of Ti O₂ redshift.In this case,the synergistic effect of adsorption and catalysis can be achieved by two materials.Aminated graphene oxide was synthesized by condensation of graphene oxide and diethylenetriamine.A series of high catalytic nanostructured NGO-Ti O₂ composite catalysts were self-assembled by a two-phase system of toluene and water.The crystal structure,morphology,and optical properties of the composite catalysts were characterized by X-ray diffraction,Scanning electron microscope,and Ultraviolet-visible spectrometer and so on.The degradation of methyl orange dye under simulated solar illumination was used to evaluate the performance of the composite catalysts.Though the particle size of the commercial Ti O₂ used in the work was larger than that synthesized in the laboratory,the NGO-Ti O₂catalyst had greater performance than Ti O₂and GO-Ti O₂ prepared in the same way,and the catalytic performance of NGO-Ti O₂improved with the increasing of NGO loading amount in an appropriate ratio.The mechanism of NGO improving Ti O₂ performance was fully explained from a new perspective.The introduction of NGO not only improves the catalytic performance of Ti O₂,the post-treatment problem of relying on adsorption to deal with pollutants can also solve.The catalytic activity of Ti O₂ is a combined action of hydroxyl radicals,superoxide radicals,hole radicals and so on.The activity evaluation of the radicals is a key content to study the catalytic mechanism.As reported in literature,the activity of superoxide radicals is assessed by p-benzoquinone,the performance of hydroxyl radicals is usually measured with tert-butanol and isopropanol,and the activity of hole radicals often analyzes by disodium edetate and potassium iodide.However,many problems affecting the results accuracy occurred when the experiments were conducted according to the way reported in the literature,for example,the color and absorbance change arising from p-benzoquinone will exert a negative impact on the evaluation of superoxide radicals,the alcohols to evaluate the activity of hydroxyl radicals show an inhibiting effect on the catalytic at low concentrations but exhibit an opposite effect with high concentrations,the result of evaluating the activities of hole radicals by ethylenediaminetetraacetic acid shows that the catalytic process is promoted greatly,these phenomena are discrepant with the conclusions reported in the literature.This research has conducted an in-depth exploration to the related content,it is concluded that the use of N₂ can evaluate the activity of superoxide radicals more conveniently,meanwhile,the theory that specific organic solvents can improve the catalytic effect by increasing the existence time of free radicals is proposed and the conclusion that the activity of hole radicals evaluated accurately with KI 1-3mmol is obtained.