Sr-doped nanostructured crystalline TiO2 microspheres were fabricated by modifying the bare microspheres with the method of soaking in strontium nitrate solution and heat treatment.The morphology,crystal structure and...Sr-doped nanostructured crystalline TiO2 microspheres were fabricated by modifying the bare microspheres with the method of soaking in strontium nitrate solution and heat treatment.The morphology,crystal structure and photoabsorption ability were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） and UV-Vis spectrophotometer.The observation of SEM showed that both the bare and Sr-doped microspheres presented the same honeycomb porous morphology.The XRD spectra affirmed that the incorporation of Sr was in the form of strontium titanate(SrTiO3) as eutectic structure with anatase TiO2.The photocatalytic efficiency of Sr-doped TiO2 microspheres was assessed by monitoring the photodecomposition of KN-R dye.The results reveal that Sr-doped microspheres provided a higher efficiency than the unmodified,which was consistent with the analysis results of UV-Vis absorption spectra.Obvious phenomenon of red-shift on UV-Vis spectrum was seen in comparison with the bare microspheres.Both the phenomena of red-shift and the photocatalytic activity improvement were attributed to the synergistic action between SrTiO3 and anatase TiO2.展开更多
TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fl...TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.展开更多
文摘Sr-doped nanostructured crystalline TiO2 microspheres were fabricated by modifying the bare microspheres with the method of soaking in strontium nitrate solution and heat treatment.The morphology,crystal structure and photoabsorption ability were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） and UV-Vis spectrophotometer.The observation of SEM showed that both the bare and Sr-doped microspheres presented the same honeycomb porous morphology.The XRD spectra affirmed that the incorporation of Sr was in the form of strontium titanate(SrTiO3) as eutectic structure with anatase TiO2.The photocatalytic efficiency of Sr-doped TiO2 microspheres was assessed by monitoring the photodecomposition of KN-R dye.The results reveal that Sr-doped microspheres provided a higher efficiency than the unmodified,which was consistent with the analysis results of UV-Vis absorption spectra.Obvious phenomenon of red-shift on UV-Vis spectrum was seen in comparison with the bare microspheres.Both the phenomena of red-shift and the photocatalytic activity improvement were attributed to the synergistic action between SrTiO3 and anatase TiO2.
基金supported by the National Natural Science Foundation of China(51672312,21373275)the Science and Technology Program of Wuhan,China(2016010101010018,2015070504020220)the Dean’s Research Fund–04257 from the Education University of Hong Kong~~
文摘TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.
