TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO...TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 ℃ are of pure anatase and rutile, respectively. The scanning electron microscope （SEM） observations reveal that the crystal grain size increases with the annealing temperature, and the high resolution transmission electron microscopy （HRTEM） investigations further indicate that the samples are well crystallized, confirming that Mn has doped into the TiO2 crystal lattice effectively. The room temperature ferromagnetism, which could be explained within the scope of the bound magnetic polaron （BMP） theory, is detected in the Mn-TiO2 samples with Mn concentration of 2 at%, and the magnetization of the powders annealed at 500 ℃ is stronger than that of the sample treated at 800 ℃. The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.展开更多
Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 ...Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD（chemical oxygen demand） in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.展开更多
基金Project supported by the Innovation Foundation of BUAA for PhD Graduates (Grant No. 292122)Equipment Research Foundation of China
文摘TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 ℃ are of pure anatase and rutile, respectively. The scanning electron microscope （SEM） observations reveal that the crystal grain size increases with the annealing temperature, and the high resolution transmission electron microscopy （HRTEM） investigations further indicate that the samples are well crystallized, confirming that Mn has doped into the TiO2 crystal lattice effectively. The room temperature ferromagnetism, which could be explained within the scope of the bound magnetic polaron （BMP） theory, is detected in the Mn-TiO2 samples with Mn concentration of 2 at%, and the magnetization of the powders annealed at 500 ℃ is stronger than that of the sample treated at 800 ℃. The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.
文摘Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD（chemical oxygen demand） in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.
