To develop efficient visible-light photocatalysis on α-Fe2O3, it is highly desirable to promote visible-light-excited high-energy-level electron transfer to a proper energy platform thermodynamically. Herein, based o...To develop efficient visible-light photocatalysis on α-Fe2O3, it is highly desirable to promote visible-light-excited high-energy-level electron transfer to a proper energy platform thermodynamically. Herein, based on the transient-state surface photovoltage responses and the atmosphere-controlled steady-state surface photovoltage spectra, it is demonstrated that the lifetime and separation of photogenerated charges of nanosized α-Fe2O3 are increased after coupling a proper amount of nanocrystalline SnO2. This naturally leads to greatly improved photocatalytic activities for CO2 reduction and acetaldehyde degradation. It is suggested that the enhanced charge separation results from the electron transfer from α-Fe2O3 to SnO2, which acts as a proper energy platform. Based on the photocurrent action spectra, it is confirmed that the coupled SnO2 exhibits longer visible-light threshold wavelength （-590 nm） compared with the coupled TiO2 （-550 nm）, indicating that the energy platform introduced by SnO2 would accept more photogenerated electrons from α-Fe2O3. Moreover, electrochemical reduction experiments proved that the coupled SnO2 possesses better catalytic ability for reducing CO2 and O2. These are well responsible for the much efficient photocatalysis on SnO2-coupled α-Fe2O3.展开更多
Al2O3/SnO2 co-nanoparticles were prepared with a modified sol-gel technique followed by a thermal treatment process. With these co-nanoparticles the grafted collagen-Al2O3/SnO2 nanocomposites were obtained using a sup...Al2O3/SnO2 co-nanoparticles were prepared with a modified sol-gel technique followed by a thermal treatment process. With these co-nanoparticles the grafted collagen-Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X-ray diffraction, FT-IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co-nanoparticles showed a narrow distribution of size between 20-40 nm and could be uniformly absorbed on the tri-helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co-nanoparticles with an increase of degradation temperature from 39 to 210 ℃ and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co-nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.展开更多
The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In catio...The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In cation ratio, metal salt total concentration, precipitation pH value and aging time, the nanocrystalline powders were successfully derived with chemical homogeneity and superior thermal stability, compared with the single component oxides. The particle size and morphology, surface area, and thermal and phase stabilities were characterized using TEM, TG-DTA, BET and XRD. The sensing tests showed that the Sn-In com-posites exhibit high sensitivity and selectivity for CO and NO2. The introduction of TiO2 enhanced CH4 sensitivity and selectivity, particularly, additives of Pd and Al2O3 as a dopant and surface modification greatly enhanced the sensing properties. The sensitivity depended on the composition of composites, calcination temperature and operating temperature. The optimal values were (25%In2O3- 75%SnO2)-20%TiO2 for ternary composite, 600 and 300℃, respectively. Temperature-programmed de-sorption (TPD) studies were employed to explain the gas adsorption behavior dis-played by the surface of nanocomposites and X-ray photoelectron spectroscopic (XPS) analysis was used to confirm the electronic interactions existing between oxide components. The sensing mechanism of the nanocomposites was attributed to chemical and electronic synergistic effects.展开更多
基金We are grateful for financial support from the National Natural Science Foundation of China （Nos. U1401245 and 21501052）, the National Basic Research Program of China （No. 2014CB660814）, the Project of Chinese Ministry of Education （No. 213011A）, Special Funding for Postdoctoral of Heilongjiang Province （No. LBH- TZ06019） and the Science Foundation for Excellent Youth of Harbin City of China （No. 2014RFYXJ002）.
文摘To develop efficient visible-light photocatalysis on α-Fe2O3, it is highly desirable to promote visible-light-excited high-energy-level electron transfer to a proper energy platform thermodynamically. Herein, based on the transient-state surface photovoltage responses and the atmosphere-controlled steady-state surface photovoltage spectra, it is demonstrated that the lifetime and separation of photogenerated charges of nanosized α-Fe2O3 are increased after coupling a proper amount of nanocrystalline SnO2. This naturally leads to greatly improved photocatalytic activities for CO2 reduction and acetaldehyde degradation. It is suggested that the enhanced charge separation results from the electron transfer from α-Fe2O3 to SnO2, which acts as a proper energy platform. Based on the photocurrent action spectra, it is confirmed that the coupled SnO2 exhibits longer visible-light threshold wavelength （-590 nm） compared with the coupled TiO2 （-550 nm）, indicating that the energy platform introduced by SnO2 would accept more photogenerated electrons from α-Fe2O3. Moreover, electrochemical reduction experiments proved that the coupled SnO2 possesses better catalytic ability for reducing CO2 and O2. These are well responsible for the much efficient photocatalysis on SnO2-coupled α-Fe2O3.
基金Project supported by the National Natural Science Foundation of China for Distinguished Young Scholar （No. 20325518）, Creative Research Groups （No. 20521503） and a key program （No. 20535010） to JHX, the Program for New Century Excellent Talents in Universities of Education Ministry of China to ZYM （No. NCET-04-0482）, and the Postdoctoral Foundation of China to CY （No. 2005038234）.
文摘Al2O3/SnO2 co-nanoparticles were prepared with a modified sol-gel technique followed by a thermal treatment process. With these co-nanoparticles the grafted collagen-Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X-ray diffraction, FT-IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co-nanoparticles showed a narrow distribution of size between 20-40 nm and could be uniformly absorbed on the tri-helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co-nanoparticles with an increase of degradation temperature from 39 to 210 ℃ and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co-nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.
基金the National Natural Science Foundation of China (Grant No.20577001)Beijing Natural Science Foundation (Grant Nos. 8072018, 8062011)
文摘The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In cation ratio, metal salt total concentration, precipitation pH value and aging time, the nanocrystalline powders were successfully derived with chemical homogeneity and superior thermal stability, compared with the single component oxides. The particle size and morphology, surface area, and thermal and phase stabilities were characterized using TEM, TG-DTA, BET and XRD. The sensing tests showed that the Sn-In com-posites exhibit high sensitivity and selectivity for CO and NO2. The introduction of TiO2 enhanced CH4 sensitivity and selectivity, particularly, additives of Pd and Al2O3 as a dopant and surface modification greatly enhanced the sensing properties. The sensitivity depended on the composition of composites, calcination temperature and operating temperature. The optimal values were (25%In2O3- 75%SnO2)-20%TiO2 for ternary composite, 600 and 300℃, respectively. Temperature-programmed de-sorption (TPD) studies were employed to explain the gas adsorption behavior dis-played by the surface of nanocomposites and X-ray photoelectron spectroscopic (XPS) analysis was used to confirm the electronic interactions existing between oxide components. The sensing mechanism of the nanocomposites was attributed to chemical and electronic synergistic effects.
