The fusion of infrared and visible images should emphasize the salient targets in the infrared image while preserving the textural details of the visible images.To meet these requirements,an autoencoder-based method f...The fusion of infrared and visible images should emphasize the salient targets in the infrared image while preserving the textural details of the visible images.To meet these requirements,an autoencoder-based method for infrared and visible image fusion is proposed.The encoder designed according to the optimization objective consists of a base encoder and a detail encoder,which is used to extract low-frequency and high-frequency information from the image.This extraction may lead to some information not being captured,so a compensation encoder is proposed to supplement the missing information.Multi-scale decomposition is also employed to extract image features more comprehensively.The decoder combines low-frequency,high-frequency and supplementary information to obtain multi-scale features.Subsequently,the attention strategy and fusion module are introduced to perform multi-scale fusion for image reconstruction.Experimental results on three datasets show that the fused images generated by this network effectively retain salient targets while being more consistent with human visual perception.展开更多
Elemental doping is an effective strategy for tuning the band structure of graphite carbon nitride(CN)to enhance its photocatalytic performance.In this study,sodium(Na)and oxygen(O)co-doped carbon nitride(Na/O-CN_(x),...Elemental doping is an effective strategy for tuning the band structure of graphite carbon nitride(CN)to enhance its photocatalytic performance.In this study,sodium(Na)and oxygen(O)co-doped carbon nitride(Na/O-CN_(x),x=1.0,2.0,3.0,4.0)was synthesized via solid-phase reaction of sodium citrate(NaCA)and pure CN powder in the Teflon-sealed autoclave under air conditions at 180℃.Surface area of Na/O-CN_(3.0) is measured to be 18.8 m^(2)/g,increasing by 60.7%compared to that of pure CN(11.7 m^(2)/g).Bandgap energy of Na/O-CN_(3.0) is determined to be 2.68 eV,marginally lower than that of pure CN(2.70 eV),thereby enhancing its capacity for sunlight absorption.Meanwhile,the incorporation of Na and O atoms into Na/O-CN_(x) is found to effectively reduce recombination rates of photogenerated electron-hole pairs.As a result,Na/O-CN_(x) samples exhibit markedly enhanced photocatalytic hydrogen evolution activity under visible light irradiation.Notably,the optimal Na/O-CN_(3.0) sample achieves a photocatalytic hydrogen production rate of 103.2μmol·g^(–1)·h^(–1),which is 8.2 times greater than that of pure CN(11.2μmol·g^(–1)·h^(–1)).Furthermore,a series of Na/O-CN_(x)-yO_(2)(y=0,20%,40%,60%,80%,100%)samples were prepared by modulating the oxygen content within reaction atmosphere.The catalytic performance evaluations reveal that the incorporation of both Na and O atoms in Na/O-CN_(3.0) enhances photocatalytic activity.This study also introduces novel methodologies for synthesis of metal atom-doped CN materials at lower temperature,highlighting the synergistic effect of Na and O atoms in photocatalytic hydrogen production of Na/O-CN_(x) samples.展开更多
The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydroge...The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.展开更多
Semiconductor photocatalysis has been considered as a potential technology for the removal of organic dyes from wastewater.The development of photocatalysts with high stability and strong catalytic activity is the mos...Semiconductor photocatalysis has been considered as a potential technology for the removal of organic dyes from wastewater.The development of photocatalysts with high stability and strong catalytic activity is the most important in application.Visible-light-induced NiCo_(2)O_(4)@Co_(3)O_(4) core/shell heterojunctions were synthesized via a sol-gel method in this paper.Compared to bare NiCo_(2)O_(4) and Co_(3)O_(4),NiCo_(2)O_(4)@Co_(3)O_(4) showed a remarkably enhanced removal rate towards congo red(CR)degradation with 98.4%of the removal rate to CR at 120 min under irradiation.The excellent performance of NiCo_(2)O_(4)@Co_(3)O_(4) benefits from the effective separation of photogenerated electron-holes by forming a heterojunction,and the rapid transfer efficiency of photo-generated charge carriers results from the core/shell architectures.A mechanism that NiCo_(2)O_(4)@Co_(3)O_(4) degrades CR to harmless inorganic substances by h^(+),•O-2 and•OH during the photocatalytic process was proposed.展开更多
Iron(Ⅱ) tetrasulfophthalocyanine(FeTSPc) ,as a novel mimetic enzyme of peroxidase,was used in the synthesis of a conducting polyaniline(PANI) /sodium dodecylsulfate(SDS) complex in SDS aqueous micellar solutions. The...Iron(Ⅱ) tetrasulfophthalocyanine(FeTSPc) ,as a novel mimetic enzyme of peroxidase,was used in the synthesis of a conducting polyaniline(PANI) /sodium dodecylsulfate(SDS) complex in SDS aqueous micellar solutions. The effects of pH,concentrations of aniline,SDS and H2O2,and reaction time on polymerization of aniline were studied in this case as shown by UV-Vis absorption spectroscopy. The results show that a wide range of pH(0.5-4.0) is required to produce the conducting PANI,and the optimal pH is 1.0 in SDS micelle. The optimal concentrations of aniline,SDS and H2O2 in feed,and reaction time in this case for the production of conducting PANI are respectively 10 mmol/L,10 mmol/L,25 mmol/L,and 15 h. FT-IR spectrum,elemental analysis,conductivity,cyclic voltammetry and thermogravimetric analysis confirm the thermal stability and electroactive form of PANI.展开更多
Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment...Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment where the robot locates. Salient local regions are detected from these images using center-surround difference method, which computes opponencies of color and texture among multi-scale image spaces. And then they are organized using hidden Markov model (HMM) to form the vertex of topological map. So localization, that is place recognition in our system, can be converted to evaluation of HMM. Experimental results show that the saliency detection is immune to the changes of scale, 2D rotation and viewpoint etc. The created topological map has smaller size and a higher ratio of recognition is obtained.展开更多
Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant...Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation.Effects of various parameters such as catalyst amount,initial MO concentration,solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions.The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model,and a surface reaction,where the dyes are absorbed,is the controlling step of the process.Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range.The photodecolorization of MO is more efficient in acidic media than alkaline media.The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation,which confirms the reusability of AC/n-CdS/CS composite catalyst.展开更多
The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. Th...The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. The energy band structures of TiO2 photocatalysts were analyzed. The photocatalytic activities of the TiO2 photocatalysts were investigated by splitting of water for 02 evolution. The results indicate that the band gaps of WO3 and V205 are about 2.8 and 2.14 eV, respectively, and the band gap of rutile TiO2 is about 3.08 eV. Speeds of water splitting for 2%WO3-TiO2 and 8%V2O5-TiO2 photocatalysts are 420 and 110 μmol/（L.h）, respectively, under UV light irradiation. V2O5 and WO3 compounded with suitable concentration can improve the photocatalytic activity of TiO2 with Fe3＋ as electron acceptor.展开更多
The role of oxygen and the generation of active radicals in the photocatalitic degradation of phenol were investigated using the eosin sensitized TiO2 as photocatalyst under visible light irradiation. Diffuse reflecta...The role of oxygen and the generation of active radicals in the photocatalitic degradation of phenol were investigated using the eosin sensitized TiO2 as photocatalyst under visible light irradiation. Diffuse reflectance spectra show that the absorbancy range of eosin/TiO2 is expanded from 378 nm (TiO2 ) to about 600 nm. The photocatalitic degradation of phenol is almost stopped when the eosin/TiO2 system is saturated with N2 , which indicates the significance of O2 . The addition of NaN 3 (a quencher of single oxygen) causes about a 62% decrease in the phenol degradation. The phenol degradation ratio is dropped from 92% to 75% when the isopropanol (a quencher of hydroxyl radical) is present in the system. The experimental results show that there are singlet oxygen and hydroxyl radical generated in the eosin/TiO2 system under visible light irradiation. The changes of absorbancy indicate that the hydrogen peroxide might be produced. Through the analysis and comparison, it is found that the singlet oxygen is the predominant active radical for the degradation of phenol.展开更多
Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were i...Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.展开更多
2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4...2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4-diol （2b） was characterized by X-ray diffraction and compared with the crystal structures of anti- and syn-2,4-diphenylpentane-2,4-diols （la and lb）. X-ray diffraction indicates that inter and intra-molecular hydrogen bonds are formed in the crystal structures. There is n-n staking interaction in lb and 2b. Good linear correlations and similar results are found between the experimental 1H and 13C NMR chemical shifts （6~exp） and GIAO （Gauge Independent Atomic Orbital） method calculated magnetic isotropic shielding tensors （acalc）. HOMO and LUMO molecular orbitals were calculated at the same levels with the different results. UV-vis absorption spectra of the compounds were recorded in EtOH, MeCN, n-BuOH and cyclohexane with different dielectric constants. It is found that the solvent effect is obvious when e is 24.85（EtOH）, 35.69（MeCN） and it is weak when e is decreased to 17.33（n-BuOH）, 1.18 （cyclohexane）.展开更多
TiO2/bauxite-tailings （TiO2/BTs） composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry （XRD）, scanning electronic microscopy （SEM） and N2 adsorption analysis....TiO2/bauxite-tailings （TiO2/BTs） composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry （XRD）, scanning electronic microscopy （SEM） and N2 adsorption analysis. The photocatalytic performance of TiO2/BTs composites was evaluated with UV-Vis spectrophotometer following the changes of phenol concentration under different illumination time. Effects of the calcination temperature, the pH and the cycles on the photocatalytic activity of TiO2/BTs composites were investigated. The composites calcined at 500 and 600 ℃ exhibit the best photocatalytic performance, and the phenol degradation ratios reacting for 40 and 160 rain reach 35% and 78% respectively under the same conditions, higher than those of 29% and 76% of the Degussa P25（TiO2）. The ability of TiO2/BTs500 （BTs500 represents bauxite-tailings calcined at 500 ℃） composites to degrade phenol increases with decreasing pH.展开更多
TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measure...TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V2O5/TiO2 was investigated by employing splitting of water for O2 evolution. The results indicate that V2O5 loading can pronouncedly improve the photocatalytic activity of TiO2 with Fe3+ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V2O5 is 8%,and the largest speed of O2 evolution for 8%V2O5 (mass fraction) loaded TiO2 catalyst is 118.2 μmol/(L.h) under UV irradiation,and 83.7 μmol/(L.h) under visible light irradiation.展开更多
基金Supported by the Henan Province Key Research and Development Project(231111211300)the Central Government of Henan Province Guides Local Science and Technology Development Funds(Z20231811005)+2 种基金Henan Province Key Research and Development Project(231111110100)Henan Provincial Outstanding Foreign Scientist Studio(GZS2024006)Henan Provincial Joint Fund for Scientific and Technological Research and Development Plan(Application and Overcoming Technical Barriers)(242103810028)。
文摘The fusion of infrared and visible images should emphasize the salient targets in the infrared image while preserving the textural details of the visible images.To meet these requirements,an autoencoder-based method for infrared and visible image fusion is proposed.The encoder designed according to the optimization objective consists of a base encoder and a detail encoder,which is used to extract low-frequency and high-frequency information from the image.This extraction may lead to some information not being captured,so a compensation encoder is proposed to supplement the missing information.Multi-scale decomposition is also employed to extract image features more comprehensively.The decoder combines low-frequency,high-frequency and supplementary information to obtain multi-scale features.Subsequently,the attention strategy and fusion module are introduced to perform multi-scale fusion for image reconstruction.Experimental results on three datasets show that the fused images generated by this network effectively retain salient targets while being more consistent with human visual perception.
基金National Natural Science Foundation of China(21806023)Natural Science Foundation of Hunan Province(2021JJ40199)+2 种基金Education Department Foundation of Hunan Province(20C0813)Hunan University of Science and Technology Fundamental Research FundsPostgraduate Scientific Research Innovation Project of Hunan Province(CX20240877)。
文摘Elemental doping is an effective strategy for tuning the band structure of graphite carbon nitride(CN)to enhance its photocatalytic performance.In this study,sodium(Na)and oxygen(O)co-doped carbon nitride(Na/O-CN_(x),x=1.0,2.0,3.0,4.0)was synthesized via solid-phase reaction of sodium citrate(NaCA)and pure CN powder in the Teflon-sealed autoclave under air conditions at 180℃.Surface area of Na/O-CN_(3.0) is measured to be 18.8 m^(2)/g,increasing by 60.7%compared to that of pure CN(11.7 m^(2)/g).Bandgap energy of Na/O-CN_(3.0) is determined to be 2.68 eV,marginally lower than that of pure CN(2.70 eV),thereby enhancing its capacity for sunlight absorption.Meanwhile,the incorporation of Na and O atoms into Na/O-CN_(x) is found to effectively reduce recombination rates of photogenerated electron-hole pairs.As a result,Na/O-CN_(x) samples exhibit markedly enhanced photocatalytic hydrogen evolution activity under visible light irradiation.Notably,the optimal Na/O-CN_(3.0) sample achieves a photocatalytic hydrogen production rate of 103.2μmol·g^(–1)·h^(–1),which is 8.2 times greater than that of pure CN(11.2μmol·g^(–1)·h^(–1)).Furthermore,a series of Na/O-CN_(x)-yO_(2)(y=0,20%,40%,60%,80%,100%)samples were prepared by modulating the oxygen content within reaction atmosphere.The catalytic performance evaluations reveal that the incorporation of both Na and O atoms in Na/O-CN_(3.0) enhances photocatalytic activity.This study also introduces novel methodologies for synthesis of metal atom-doped CN materials at lower temperature,highlighting the synergistic effect of Na and O atoms in photocatalytic hydrogen production of Na/O-CN_(x) samples.
基金Project(2013AA064102)supported by the National High Technology Research and Development Program of ChinaProject(B14034)supported by the Program of Introducing Talents of Discipline to Universities,ChinaProject supported by the 2011 Collaborative Innovation Center for Clean and Efficient utilization of Strategic Metal Mineral Resources,China
文摘The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.
基金Project(2017TP1031)supported by the Hunan Key Laboratory for Rare Earth Functional Materials,ChinaProject(2020JJ4735)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2018GK4001)supported by Science and Technology Department of Hunan Province Tackling Key Scientific and Technological Problems and Transformation of Major Scientific and Technological Achievements,ChinaProject(CSUZC202126)supported by the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China。
文摘Semiconductor photocatalysis has been considered as a potential technology for the removal of organic dyes from wastewater.The development of photocatalysts with high stability and strong catalytic activity is the most important in application.Visible-light-induced NiCo_(2)O_(4)@Co_(3)O_(4) core/shell heterojunctions were synthesized via a sol-gel method in this paper.Compared to bare NiCo_(2)O_(4) and Co_(3)O_(4),NiCo_(2)O_(4)@Co_(3)O_(4) showed a remarkably enhanced removal rate towards congo red(CR)degradation with 98.4%of the removal rate to CR at 120 min under irradiation.The excellent performance of NiCo_(2)O_(4)@Co_(3)O_(4) benefits from the effective separation of photogenerated electron-holes by forming a heterojunction,and the rapid transfer efficiency of photo-generated charge carriers results from the core/shell architectures.A mechanism that NiCo_(2)O_(4)@Co_(3)O_(4) degrades CR to harmless inorganic substances by h^(+),•O-2 and•OH during the photocatalytic process was proposed.
基金Project(07JJ6020) supported by the Hunan Provincial Natural Science Foundation of ChinaProject(2007-24-3) supported by the Huaihua Key Science and Technology Program, China
文摘Iron(Ⅱ) tetrasulfophthalocyanine(FeTSPc) ,as a novel mimetic enzyme of peroxidase,was used in the synthesis of a conducting polyaniline(PANI) /sodium dodecylsulfate(SDS) complex in SDS aqueous micellar solutions. The effects of pH,concentrations of aniline,SDS and H2O2,and reaction time on polymerization of aniline were studied in this case as shown by UV-Vis absorption spectroscopy. The results show that a wide range of pH(0.5-4.0) is required to produce the conducting PANI,and the optimal pH is 1.0 in SDS micelle. The optimal concentrations of aniline,SDS and H2O2 in feed,and reaction time in this case for the production of conducting PANI are respectively 10 mmol/L,10 mmol/L,25 mmol/L,and 15 h. FT-IR spectrum,elemental analysis,conductivity,cyclic voltammetry and thermogravimetric analysis confirm the thermal stability and electroactive form of PANI.
基金Projects(60234030 ,60404021) supported by the National Natural Science Foundation of China
文摘Based on salient visual regions for mobile robot navigation in unknown environments, a new place recognition system was presented. The system uses monocular camera to acquire omni-directional images of the environment where the robot locates. Salient local regions are detected from these images using center-surround difference method, which computes opponencies of color and texture among multi-scale image spaces. And then they are organized using hidden Markov model (HMM) to form the vertex of topological map. So localization, that is place recognition in our system, can be converted to evaluation of HMM. Experimental results show that the saliency detection is immune to the changes of scale, 2D rotation and viewpoint etc. The created topological map has smaller size and a higher ratio of recognition is obtained.
基金Project(21007044) supported by the National Natural Science Foundation of ChinaProject(20050532009) supported by the Doctoral Foundation of Ministry of Education of China
文摘Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation.Effects of various parameters such as catalyst amount,initial MO concentration,solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions.The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model,and a surface reaction,where the dyes are absorbed,is the controlling step of the process.Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range.The photodecolorization of MO is more efficient in acidic media than alkaline media.The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation,which confirms the reusability of AC/n-CdS/CS composite catalyst.
基金Project(11JJ5010) supported by the Natural Science Foundation of Hunan Province, ChinaProject(2011RS4069) supported by the Planned Science and Technology Program of Hunan Province, ChinaProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. The energy band structures of TiO2 photocatalysts were analyzed. The photocatalytic activities of the TiO2 photocatalysts were investigated by splitting of water for 02 evolution. The results indicate that the band gaps of WO3 and V205 are about 2.8 and 2.14 eV, respectively, and the band gap of rutile TiO2 is about 3.08 eV. Speeds of water splitting for 2%WO3-TiO2 and 8%V2O5-TiO2 photocatalysts are 420 and 110 μmol/（L.h）, respectively, under UV light irradiation. V2O5 and WO3 compounded with suitable concentration can improve the photocatalytic activity of TiO2 with Fe3＋ as electron acceptor.
基金Project(8451063201001261) supported by the Guangdong Natural Science Fund Committee,ChinaProject(LYM08022) supported by the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China+1 种基金Project (2007A032400001, 2008A030202010) supported by the Scientific and Technological Planning of Guangdong Province,ChinaProject(216113132) supported by the Scientific Research Cultivation and Innovation Fund, Jinan University,China
文摘The role of oxygen and the generation of active radicals in the photocatalitic degradation of phenol were investigated using the eosin sensitized TiO2 as photocatalyst under visible light irradiation. Diffuse reflectance spectra show that the absorbancy range of eosin/TiO2 is expanded from 378 nm (TiO2 ) to about 600 nm. The photocatalitic degradation of phenol is almost stopped when the eosin/TiO2 system is saturated with N2 , which indicates the significance of O2 . The addition of NaN 3 (a quencher of single oxygen) causes about a 62% decrease in the phenol degradation. The phenol degradation ratio is dropped from 92% to 75% when the isopropanol (a quencher of hydroxyl radical) is present in the system. The experimental results show that there are singlet oxygen and hydroxyl radical generated in the eosin/TiO2 system under visible light irradiation. The changes of absorbancy indicate that the hydrogen peroxide might be produced. Through the analysis and comparison, it is found that the singlet oxygen is the predominant active radical for the degradation of phenol.
基金Project(JB141405)supported by the Fundamental Research Funds for the Central Universities of China
文摘Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.
基金Projects(21072053,20772028)supported by the National Natural Science Foundation of ChinaProjects(10K025,11C0527)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(LKF0901)supported by the Open Foundation of Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education,Hunan University of Science and Technology,China
文摘2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4-diol （2b） was characterized by X-ray diffraction and compared with the crystal structures of anti- and syn-2,4-diphenylpentane-2,4-diols （la and lb）. X-ray diffraction indicates that inter and intra-molecular hydrogen bonds are formed in the crystal structures. There is n-n staking interaction in lb and 2b. Good linear correlations and similar results are found between the experimental 1H and 13C NMR chemical shifts （6~exp） and GIAO （Gauge Independent Atomic Orbital） method calculated magnetic isotropic shielding tensors （acalc）. HOMO and LUMO molecular orbitals were calculated at the same levels with the different results. UV-vis absorption spectra of the compounds were recorded in EtOH, MeCN, n-BuOH and cyclohexane with different dielectric constants. It is found that the solvent effect is obvious when e is 24.85（EtOH）, 35.69（MeCN） and it is weak when e is decreased to 17.33（n-BuOH）, 1.18 （cyclohexane）.
基金Project(2005CB623701) supported by the National Key Basic Research Program of China
文摘TiO2/bauxite-tailings （TiO2/BTs） composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry （XRD）, scanning electronic microscopy （SEM） and N2 adsorption analysis. The photocatalytic performance of TiO2/BTs composites was evaluated with UV-Vis spectrophotometer following the changes of phenol concentration under different illumination time. Effects of the calcination temperature, the pH and the cycles on the photocatalytic activity of TiO2/BTs composites were investigated. The composites calcined at 500 and 600 ℃ exhibit the best photocatalytic performance, and the phenol degradation ratios reacting for 40 and 160 rain reach 35% and 78% respectively under the same conditions, higher than those of 29% and 76% of the Degussa P25（TiO2）. The ability of TiO2/BTs500 （BTs500 represents bauxite-tailings calcined at 500 ℃） composites to degrade phenol increases with decreasing pH.
基金Project(08JJ3022) supported by the Natural Science Foundation of Hunan Province, China
文摘TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V2O5/TiO2 was investigated by employing splitting of water for O2 evolution. The results indicate that V2O5 loading can pronouncedly improve the photocatalytic activity of TiO2 with Fe3+ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V2O5 is 8%,and the largest speed of O2 evolution for 8%V2O5 (mass fraction) loaded TiO2 catalyst is 118.2 μmol/(L.h) under UV irradiation,and 83.7 μmol/(L.h) under visible light irradiation.
