Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound sampies were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and UV/Vis diffus...Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound sampies were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and UV/Vis diffuse reflectance spectra （DRS）. The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile ; the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20 nm of pure TiO2 to about 10 nm; the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability. The results of the photocatalytic experiments show that doping with Ce content of 0.08% -0.4% can increase the photocatalytic activity of TiO2; however, doping with Ce content of 0.5% -2.5% can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4% in the range of our experiments.展开更多
Unlike inorganic quantum dots,fluorescent graphene quantum dots(GQDs)display excitation-dependent multiple color emission.In this study,we report N-doped GQDs(N-GQDs)with tailored single color emission by tuning p-con...Unlike inorganic quantum dots,fluorescent graphene quantum dots(GQDs)display excitation-dependent multiple color emission.In this study,we report N-doped GQDs(N-GQDs)with tailored single color emission by tuning p-conjugation degree,which is comparable to the inorganic quantum dot.Starting from citric acid and diethylenetriamine,as prepared N-GQDs display blue,green,and yellow light emission by changing the reaction solvent from water,dimethylformamide(DMF),and solvent free.The X-ray photoelectron spectroscopy,ultraviolet-visible spectra results clearly show the N-GQDs with blue emission(N-GQDs-B)have relatively short effective conjugation length and more carboxyl group because H_(2)O is a polar protic solvent,which tends to donate proton to the reagent to depress the H_(2)O elimination reaction.On the other hand,the polar aprotic solvent(DMF)cannot donate hydrogen,the elimination of H_(2)O is promoted and more nitrogen units enter GQD framework.With the increase of effective p-conjugation length and N content,the emission band of N-GQDS red-shifts to green and yellow.We also demonstrate that N-GQDs could be a potential great biomarker for fluorescent bioimaging.展开更多
文摘Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound sampies were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and UV/Vis diffuse reflectance spectra （DRS）. The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile ; the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20 nm of pure TiO2 to about 10 nm; the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability. The results of the photocatalytic experiments show that doping with Ce content of 0.08% -0.4% can increase the photocatalytic activity of TiO2; however, doping with Ce content of 0.5% -2.5% can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4% in the range of our experiments.
基金The authors thank the National Natural Science Foundation of China(No.21301166,21201159,61306081,and 61176016)Science and Technology Department of Jilin Province(No.20130522127JH)are gratefully acknowledged+1 种基金ZS thanks the support of the‘Hundred Talent Program’of CAS and Innovation and Entrepreneurship Program of JilinThe project was supported by Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry and the open research fund program of the State Key Laboratory of Luminescence and Applications.
文摘Unlike inorganic quantum dots,fluorescent graphene quantum dots(GQDs)display excitation-dependent multiple color emission.In this study,we report N-doped GQDs(N-GQDs)with tailored single color emission by tuning p-conjugation degree,which is comparable to the inorganic quantum dot.Starting from citric acid and diethylenetriamine,as prepared N-GQDs display blue,green,and yellow light emission by changing the reaction solvent from water,dimethylformamide(DMF),and solvent free.The X-ray photoelectron spectroscopy,ultraviolet-visible spectra results clearly show the N-GQDs with blue emission(N-GQDs-B)have relatively short effective conjugation length and more carboxyl group because H_(2)O is a polar protic solvent,which tends to donate proton to the reagent to depress the H_(2)O elimination reaction.On the other hand,the polar aprotic solvent(DMF)cannot donate hydrogen,the elimination of H_(2)O is promoted and more nitrogen units enter GQD framework.With the increase of effective p-conjugation length and N content,the emission band of N-GQDS red-shifts to green and yellow.We also demonstrate that N-GQDs could be a potential great biomarker for fluorescent bioimaging.
