Controlled Synthesis Of Nano-sized TiO₂ By Ethylenediamine And Applications Of Nanocomposition Catalysis

Nano-sized TiO₂ has the advantage of nontoxicity,low cost,and high stablities in physicochemical properties to meet the requirments of environment-friendly and sustainable development,and has become the most popular inorganic semiconductor materials.The morphology,grain size,and crystal structure exert a great effect on the TiO₂ performances;and the surface states also make TiO₂ the significant differeces.In this work,ethylenediamine was used as the regulator to grow Ti O₂ with different morphologies which were surface-modified subsequently.Furthermore,Ag-TiO₂ and CuS-TiO₂ nanocomposites were employed as catalysts,and their catalystic activities were analyzied according their surface chemistry.The mian contents include as follows:1.Using the aqueous slotion of ethylenediamine,TiO₂ with different morphologies was synthized by adjusting the pH value in the mixture of tert-butyl alcohol and tetrabutyl titanate.The anatase-brookite nanoflakes and nanorods,the anatase nanoflakes and nanorods were respsctively obtained at the pH of 6.5,8,10,and 12.It is shown that ethylenediamine is not only a chelating agent but also an organic base,and controls the hydrolysis rate of titanium alkoxide and the growth rate of nanocrystal facets.2.The as-synthesized anatase nanorods of TiO₂ was mixed with acrylic acid?AA?to modify the surfaces through the solvothermal reaction at 100 ? for 24 h.The results from infrared spectroscopy and thermogravimetric analysis indicated that AA with the content of cAA= 0.54 mmol/g was successfully grafted on the surfaces of TiO₂.The as-synthesized TiO₂ contains hydroxyl groups?c-OH=1.95 mmol/g?on the surfaces,and it is suggested that the modification is conducted by the esterification of carboxyl groups with hydroxyl groups.3.The Ag-TiO₂ nanocomposite was prepared by one-step reduction.When the nanocomposite was used as catalyst in the reduction reaction of p-nitrophenol at 25 ?,the catalytic factor is 24306 s-1g-1,and activation energy is 13.24 KJ/mol.The excellent catalytic activity results from the synergistic effects of Ag with of TiO₂ in the nanocomposite.4.Mercaptopropionic acid was choosed to the binders between CuS nanoparticles and TiO₂ nanorods;the CuS-TiO₂ nanocomposite was prepared at room temperature.Under the ultraviolet irradiation,the degradation efficiency of Rhodamine dye solution reaches 83.9%,far more than data reported in literature.The degradation performance of the composite catalyst was evaluated by the contents of Cu S and the coupling agent.