To develop TiO2-based photocatalysts with visible light activity for better solar energy utilization, a simple flash oxidation method was developed by calcining commercial TiN nanoparticle to prepare N-doped TiO2 phot...To develop TiO2-based photocatalysts with visible light activity for better solar energy utilization, a simple flash oxidation method was developed by calcining commercial TiN nanoparticle to prepare N-doped TiO2 photocatalyst and TiN/TiO2 composite photocatalysts through the modulation of the calcination time and temperature. It was found that more energy and processing time were needed to prepare N-doped TiO2 photocatalyst than that of TiN/TiO2 composite photocatalyst during this process, while TiN/TiO2 composite photocatalyst bad a better visible light absorption/photocatalytic performance than that of N-doped TiO2 photocatalyst prepared from the oxidation of the same TiN precursor. Thus, the preparation of TiN/TiO2 composite photocatalyst from TiN precursor should be a more preferred approach than the preparation of N-doped TiO2 photocatalyst for visible-light-activated photocatalysis for its costeffectiveness.展开更多
Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for ...Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.展开更多
In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles ...In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO2 nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC50=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC50of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO2 nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O2^-）.Data suggested that O2^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O2^- on rutile,but increased O2^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.展开更多
In this paper, the stable structure and the electronic and optical properties of nitric oxide （NO） adsorption on the anatase TiO2 （101） surface are studied using the plane-wave ultrasoft pseudopotential method, wh...In this paper, the stable structure and the electronic and optical properties of nitric oxide （NO） adsorption on the anatase TiO2 （101） surface are studied using the plane-wave ultrasoft pseudopotential method, which is based on the density functional theory. NO adsorption on the surface is weak when the outermost layer terminates on twofold coordinated oxygen atoms, but it is remarkably enhanced on the surface containing O vacancy defects. The higher the concentration of oxygen vacancy defects, the stronger the adsorption is. The adsorption energies are 3.4528 eV （N end adsorption）, 2.6770 eV （O end adsorption）, and 4.1437 eV （horizontal adsorption）. The adsorption process is exothermic, resulting in a more stable adsorption structure. Furthermore, O vacancy defects on the TiO2 （101） surface significantly contribute to the absorption of visible light in a relatively low-energy region. A new absorption peak in the low-energy region, corresponding to an energy of 0.9 eV, is observed. However, the TiO2 （101） surface structure exhibits weak absorption in the low-energy region of visible light after NO adsorption.展开更多
The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were ...The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were calculated by use of ab initio cluster method. We carried out optimization of the geometry, calculation of the chemisorption energy and analysis of the Mulliken population to those adsorption models. According to the calculation results, it can be got that the adsorbed decomposition of NO on defect surface is more advantageous and M6 and M12 are the important models to NO chemisorption and decomposition on TiO2 surface.展开更多
Modified with gadolinium-containing layer, nanoporous titania electrode and its application in dye-sensitized solar cells were reported. The electrode prepared was characterized with UV-Vis and X-ray diffraction （XRD...Modified with gadolinium-containing layer, nanoporous titania electrode and its application in dye-sensitized solar cells were reported. The electrode prepared was characterized with UV-Vis and X-ray diffraction （XRD） techniques. The amount of gadolinium was measured with inductively coupled plasma-optical emission spectrometry （ICP-OES） experiments. The modified electrode showed reduced N3 dye adsorption ability, but increased light conversion efficiency in comparison with the non-modified electrode. The overall conversion efficiencies, determined under 400 W/m2 irradiation with tungsten-halogen lamp at room temperature, were 0.55% for non-modified and 0.74% for modified electrodes.展开更多
The TiO_2（101） surface was studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory,with emphasis on the structure,surface energy,band structure,density of states, and cha...The TiO_2（101） surface was studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory,with emphasis on the structure,surface energy,band structure,density of states, and charge population.The anatase TiO_2（101） crystal surface structure,whose outermost and second layers were terminated by twofold coordinated oxygen atoms and fivefold coordinated titanium atoms,was found to be much more stable.The surface energy of the 18-layer atoms model was 0.580 J/m2.The surface electronic structure was similar to that of the bulk and no surface state.Compared with the bulk structure,the band gap increased 0.36 eV, the Ti5c-02c bond lengths reduced 0.171（？） after relaxation,and the charges of the surface were transferred to the body.Analysis of the optical properties of the TiO_2（101） surface showed that it did not absorb in the low-energy region.An absorption edge in the ultraviolet region corresponding to the energy of 3.06 eV was found.展开更多
The capture of orthophosphates and total phosphorus from the Pudong Canal river in the Pudong District of Shanghai by TiO2 nanoparticles is studied using a rotating photoreactor and the nano-TiO2 photocatalyst Degussa...The capture of orthophosphates and total phosphorus from the Pudong Canal river in the Pudong District of Shanghai by TiO2 nanoparticles is studied using a rotating photoreactor and the nano-TiO2 photocatalyst Degussa P25. The effects of UV irradiation intensity in a range of 20-74 mW/cm^2, the loading of the TiO2 nanoparticles in a range of 0.05-0.1 g/L, irradiation time up to 4 h, and pH values in a range of 2-10.5 on the capture efficiency are investigated. The results show that the capture of orthophosphates and total P are significantly enhanced by UV irradiation; at a loading of 0.1 g/L and an irradiation intensity above 36 mW/cm^2, orthophosphates and total phosphorus are rapidly captured by TiO2 nanoparticles, causing an observed reduction from 0.4 mg/L down to 0.02 mg/L. pH values in a range of 2-10.5 have little effect on the capture efficiency of orthophosphates and total phosphorus.展开更多
基金supported financially by the National Natural Science Foundation of China(Grant Nos.51672283 and 51602316)the Basic Science Innovation Program of Shenyang National Laboratory for Materials Science(Grant Nos.Y4N56R1161 and Y5N56F2161)
文摘To develop TiO2-based photocatalysts with visible light activity for better solar energy utilization, a simple flash oxidation method was developed by calcining commercial TiN nanoparticle to prepare N-doped TiO2 photocatalyst and TiN/TiO2 composite photocatalysts through the modulation of the calcination time and temperature. It was found that more energy and processing time were needed to prepare N-doped TiO2 photocatalyst than that of TiN/TiO2 composite photocatalyst during this process, while TiN/TiO2 composite photocatalyst bad a better visible light absorption/photocatalytic performance than that of N-doped TiO2 photocatalyst prepared from the oxidation of the same TiN precursor. Thus, the preparation of TiN/TiO2 composite photocatalyst from TiN precursor should be a more preferred approach than the preparation of N-doped TiO2 photocatalyst for visible-light-activated photocatalysis for its costeffectiveness.
基金supported by the National Natural Science Foundation of China (90922022)the Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology (FSKLCC1110)the Natural Science Foundation of Fujian Province,China (2012J01032,2012J01041)
文摘Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.
基金supported in part by the NSF-REU program(National Science Foundation-Research Experiences for Undergraduates,No.#CHE-1156111)the NSF-CREST program(National Science Foundation-Centers of Research Excellencein Science and Technology,No.#HRD-0833178)
文摘In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO2 nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC50=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC50of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO2 nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O2^-）.Data suggested that O2^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O2^- on rutile,but increased O2^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61106129 and 61274128)
文摘In this paper, the stable structure and the electronic and optical properties of nitric oxide （NO） adsorption on the anatase TiO2 （101） surface are studied using the plane-wave ultrasoft pseudopotential method, which is based on the density functional theory. NO adsorption on the surface is weak when the outermost layer terminates on twofold coordinated oxygen atoms, but it is remarkably enhanced on the surface containing O vacancy defects. The higher the concentration of oxygen vacancy defects, the stronger the adsorption is. The adsorption energies are 3.4528 eV （N end adsorption）, 2.6770 eV （O end adsorption）, and 4.1437 eV （horizontal adsorption）. The adsorption process is exothermic, resulting in a more stable adsorption structure. Furthermore, O vacancy defects on the TiO2 （101） surface significantly contribute to the absorption of visible light in a relatively low-energy region. A new absorption peak in the low-energy region, corresponding to an energy of 0.9 eV, is observed. However, the TiO2 （101） surface structure exhibits weak absorption in the low-energy region of visible light after NO adsorption.
文摘The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were calculated by use of ab initio cluster method. We carried out optimization of the geometry, calculation of the chemisorption energy and analysis of the Mulliken population to those adsorption models. According to the calculation results, it can be got that the adsorbed decomposition of NO on defect surface is more advantageous and M6 and M12 are the important models to NO chemisorption and decomposition on TiO2 surface.
基金Project supported by the Polish Ministry of Science and Higher Education (N N204 023538)
文摘Modified with gadolinium-containing layer, nanoporous titania electrode and its application in dye-sensitized solar cells were reported. The electrode prepared was characterized with UV-Vis and X-ray diffraction （XRD） techniques. The amount of gadolinium was measured with inductively coupled plasma-optical emission spectrometry （ICP-OES） experiments. The modified electrode showed reduced N3 dye adsorption ability, but increased light conversion efficiency in comparison with the non-modified electrode. The overall conversion efficiencies, determined under 400 W/m2 irradiation with tungsten-halogen lamp at room temperature, were 0.55% for non-modified and 0.74% for modified electrodes.
基金Project supported by the National Natural Science Foundation of China(Nos.61106129,61274128)
文摘The TiO_2（101） surface was studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory,with emphasis on the structure,surface energy,band structure,density of states, and charge population.The anatase TiO_2（101） crystal surface structure,whose outermost and second layers were terminated by twofold coordinated oxygen atoms and fivefold coordinated titanium atoms,was found to be much more stable.The surface energy of the 18-layer atoms model was 0.580 J/m2.The surface electronic structure was similar to that of the bulk and no surface state.Compared with the bulk structure,the band gap increased 0.36 eV, the Ti5c-02c bond lengths reduced 0.171（？） after relaxation,and the charges of the surface were transferred to the body.Analysis of the optical properties of the TiO_2（101） surface showed that it did not absorb in the low-energy region.An absorption edge in the ultraviolet region corresponding to the energy of 3.06 eV was found.
基金the Innovation Research Grant (13YZ130)the Leading Academic Discipline Project(J51803) from the Shanghai Education Committeefor the research fund from Shanghai Pudong Hydrology and Water Resource Administration
文摘The capture of orthophosphates and total phosphorus from the Pudong Canal river in the Pudong District of Shanghai by TiO2 nanoparticles is studied using a rotating photoreactor and the nano-TiO2 photocatalyst Degussa P25. The effects of UV irradiation intensity in a range of 20-74 mW/cm^2, the loading of the TiO2 nanoparticles in a range of 0.05-0.1 g/L, irradiation time up to 4 h, and pH values in a range of 2-10.5 on the capture efficiency are investigated. The results show that the capture of orthophosphates and total P are significantly enhanced by UV irradiation; at a loading of 0.1 g/L and an irradiation intensity above 36 mW/cm^2, orthophosphates and total phosphorus are rapidly captured by TiO2 nanoparticles, causing an observed reduction from 0.4 mg/L down to 0.02 mg/L. pH values in a range of 2-10.5 have little effect on the capture efficiency of orthophosphates and total phosphorus.
