In order to study the effect mechanism of N-doping on the visible-light photoactivity of TiO2,N-doped and un-doped TiO2 nano-powders were prepared by an acid-catalyzed sol-gel method and characterized by X-ray diffrac...In order to study the effect mechanism of N-doping on the visible-light photoactivity of TiO2,N-doped and un-doped TiO2 nano-powders were prepared by an acid-catalyzed sol-gel method and characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),electron spin resonance(ESR),UV-Vis diffuse reflection spectra(DRS),and photoluminescence spectra(PL)techniques.Their photoactivities are evaluated by the photocatalytic degradation of methylene blue(MB)in aqueous solution under UV light and visible-light irradiation,respectively.The results reveal that the as-prepared N-doped sample with single anatase exhibits a good visible-light photoactivity,whereas its UV photoactivity decreases slightly,compared with the un-doped sample.The N-doping increases surface hydroxyl groups and forms abundant oxygen vacancies bounding single electrons.The visible-light response of the N-doped sample can be ascribed to a synergetic effect of impurity energy levels due to the substitutional N-doping and defect energy levels owing to the formation of oxygen vacancies.The separation of the photo-generated electron and hole can be promoted by the increase in both oxygen vacancies and surface hydroxyl groups,which are conducive for enhancement of photoactivity.The increase in visible-light photoactivity of the N-doped sample is related with the decrease in its PL spectral intensity in visible-light region.展开更多
This paper reported the effect of the weak damage in the Al0.25Ga0.75As/GaAs epitaxial layer induced by 0.8 MeV Si ions implantation with ion dose from 1×1014 to 5×1015 cm-2. The Raman spectra measured on th...This paper reported the effect of the weak damage in the Al0.25Ga0.75As/GaAs epitaxial layer induced by 0.8 MeV Si ions implantation with ion dose from 1×1014 to 5×1015 cm-2. The Raman spectra measured on these samples showed that there were two kinds of phonon modes existing in the epitaxial Al0.25Ga0.75As films. The strains induced in the implanted layer and the corresponding lattice parameters were also evaluated as a function of the implanted dose. In addition, the Rutherford backscattering spectrometry/channeling (RBS/C) was also measured on these samples. These two measurement techniques all confirmed that the implantation only induced weak damage in the material.展开更多
基金Research Foundation for Young Academic Core of Harbin Normal University,China(No.08XBSK89)Science and Technology Research Program of Education Bureau of Heilongjiang Province of China(No.11551115)
文摘In order to study the effect mechanism of N-doping on the visible-light photoactivity of TiO2,N-doped and un-doped TiO2 nano-powders were prepared by an acid-catalyzed sol-gel method and characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),electron spin resonance(ESR),UV-Vis diffuse reflection spectra(DRS),and photoluminescence spectra(PL)techniques.Their photoactivities are evaluated by the photocatalytic degradation of methylene blue(MB)in aqueous solution under UV light and visible-light irradiation,respectively.The results reveal that the as-prepared N-doped sample with single anatase exhibits a good visible-light photoactivity,whereas its UV photoactivity decreases slightly,compared with the un-doped sample.The N-doping increases surface hydroxyl groups and forms abundant oxygen vacancies bounding single electrons.The visible-light response of the N-doped sample can be ascribed to a synergetic effect of impurity energy levels due to the substitutional N-doping and defect energy levels owing to the formation of oxygen vacancies.The separation of the photo-generated electron and hole can be promoted by the increase in both oxygen vacancies and surface hydroxyl groups,which are conducive for enhancement of photoactivity.The increase in visible-light photoactivity of the N-doped sample is related with the decrease in its PL spectral intensity in visible-light region.
基金the National Natural Science Foundation of China (Grant No. 19975030) .
文摘This paper reported the effect of the weak damage in the Al0.25Ga0.75As/GaAs epitaxial layer induced by 0.8 MeV Si ions implantation with ion dose from 1×1014 to 5×1015 cm-2. The Raman spectra measured on these samples showed that there were two kinds of phonon modes existing in the epitaxial Al0.25Ga0.75As films. The strains induced in the implanted layer and the corresponding lattice parameters were also evaluated as a function of the implanted dose. In addition, the Rutherford backscattering spectrometry/channeling (RBS/C) was also measured on these samples. These two measurement techniques all confirmed that the implantation only induced weak damage in the material.
