Hole/electron separation and charge transfer are the key processes for enhancing the visible-light photocatalysis performance of heterogeneous photocatalytic systems.To better utilize and understand these effects,bina...Hole/electron separation and charge transfer are the key processes for enhancing the visible-light photocatalysis performance of heterogeneous photocatalytic systems.To better utilize and understand these effects,binary Ag3PO4/Ag2MoO4 hybrid materials were fabricated by a facile solution-phase reaction and characterized systematically by X-ray diffraction（XRD）,energy-dispersive spectroscopy,Fourier transform infrared spectroscopy,Raman spectroscopy,field-emission scanning electron microscopy and ultraviolet-visible diffuse-reflectance spectroscopy.Under visible-light illumination,a heterogeneous Ag3PO4/Ag/Ag2MoO4 photocatalyst was constructed and demonstrated enhanced photocatalytic activity and photostability compared with pristine Ag3PO4toward the remediation of the organic dye rhodamine B.The Ag3PO4/Ag2MoO4 hybrid catalyst with8%mole fraction of Ag2MoO4 exhibited the highest photocatalytic activity toward the removal of typical dye molecules,including methyl orange,methylene blue and phenol aqueous solution.Moreover,the mechanism of the photocatalytic enhancement was investigated via hole- and radical-trapping experiments,photocurrent measurements,electrochemical impedance spectroscopy and XRD measurements.The XRD analysis revealed that metallic Ag nanoparticles formed initially on the surface of the Ag3PO4/Ag2MoO4 composites under visible-light illumination,leading to the generation of a Ag3PO4/Ag/Ag2MoO4 Z-scheme tandem photocatalytic system.The enhanced photocatalytic activity and stability were attributed to the formation of the Ag3PO4/Ag/Ag2MoO4Z-scheme heterojunction and surface plasmon resonance of photo-reduced Ag nanoparticles on the surface.Finally,a plasmonic Z-scheme photocatalytic mechanism was proposed.This work may provide new insights into the design and preparation of advanced visible-light photocatalytic materials and facilitate their practical application in environmental issues.展开更多
The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively couple...The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively coupled plasma mass spectrometry and microwave photo-conductance decay. It is found that the behaviors of Cu precipitation are strongly dependent on the defect density. Most of the Cu contaminants tend to form precipitates homogeneously in the low density defect region, while they mostly segregate at the defects and form precipitates heterogeneously in the high density defect region. In the case of heavy contamination, the Cu precipitate can significantly reduce the carrier lifetime of multicrystalline silicon due to their Schottkydiode behavior in the silicon substrate. A 900 °C rap thermal process （RTP） phosphorus gettering anneal cannot be sufficiently effective to remove the Cu precipitates in these two regions.展开更多
We report the performance of the first self-aligned InP/InGaAs double heterojunction bipolar transistor （DHBT） produced in China. The device has a 2μm × 12μm U-shaped emitter area and demonstrates a peak comm...We report the performance of the first self-aligned InP/InGaAs double heterojunction bipolar transistor （DHBT） produced in China. The device has a 2μm × 12μm U-shaped emitter area and demonstrates a peak common-emitter DC current gain of over 300,an offset voltage of 0. 16V,a knee voltage of 0.6V,and an open-base breakdown voltage of about 6V. The HBT exhibits good microwave performance with a current gain cutoff fre- quency of 80GHz and a maximum oscillation frequency of 40GHz. These results indicate that this InP/InGaAs DHBT is suitable for low-voltage, low-power, and high-frequency applications.展开更多
Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids wer...Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.展开更多
The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatur...The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatures of melting zone are obtained for zone pass n = 1 at travel velocity of molten zone v = 5x 10^-3 m. h^-1 and initial impu- rity concentration C0〈10 μg.g-1, lnkeff is a linear function of 1/T. The keff values of A1, Ca, Cr, Fe, Cd and Sb in- crease with temperatures while that of Mg is almost constant. The purification is acceptable at lower temperature of melting zone such as 323 K. The variations of enthalpy and entropy between impurities and phosphorus in the liq- uid and solid ohases are also 19resented.展开更多
Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embe...Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution atroom temperature. Conductivity of the composite membranes scatters around 10-3 S.cm-1 at room temperature.The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion117 membrane.展开更多
The equilibrium distribution coefficients of 12 impurities （As,Fe,Ca,Co,Al,Cr,Cu,Mg,Mn,Ni,Pb,Zn） in phosphorus were obtained by measuring their effective distribution coefficients at zone travel rate of 3,5,10,15,an...The equilibrium distribution coefficients of 12 impurities （As,Fe,Ca,Co,Al,Cr,Cu,Mg,Mn,Ni,Pb,Zn） in phosphorus were obtained by measuring their effective distribution coefficients at zone travel rate of 3,5,10,15,and 20 mm·h-1 in the purification process with vertical zone-melting technique.The results indicate that the method is reliable.The equilibrium distribution coefficients are below 0.3 except arsenic.展开更多
This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impuri...This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impurities. The effects of pulp pH, solid content, reagents dosage(depressant, collector and co-collector) and conditioning time were investigated on the ratio of the modified rate constant of phosphate to the modified rate constant of iron(relative floatability). The results showed that a large dosage of depressant associated with a low value of collector resulted in a better relative floatability. Increasing the co-collector dosage, conditioning time and pH increased the relative floatability up to a certain value and thereafter resulted in diminishing the relative floatability. Meanwhile, the results indicated that increment of solid concentration increased the relative floatability in range investigated. It was also found that that maximum relative floatability(16.05) could be obtained in pulp pH, 9.32, solid percentage, 30,depressant dosage, 440 g/t, collector dosage, 560 g/t, co-collector dosage, 84.63 g/t and conditioning time,9.43 min.展开更多
The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chem...The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chemical vapor deposition(PECVD) at various substrate temperatures.Raman spectroscopy and Fourier transform infrared(FTIR) spectroscopy were used to evaluate the structural evolution,meanwhile,electronic-spin resonance(ESR) and optical measurement were applied to explore the electronic properties of P-doped a-Si:H thin films.The results revealed that the changes in materials structure affect directly the electronic properties and the doping efficiency of dopant.展开更多
基金supported by the National Natural Science Foundation of China (51672113, 51302112)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology, 2016-KF-10)~~
文摘Hole/electron separation and charge transfer are the key processes for enhancing the visible-light photocatalysis performance of heterogeneous photocatalytic systems.To better utilize and understand these effects,binary Ag3PO4/Ag2MoO4 hybrid materials were fabricated by a facile solution-phase reaction and characterized systematically by X-ray diffraction（XRD）,energy-dispersive spectroscopy,Fourier transform infrared spectroscopy,Raman spectroscopy,field-emission scanning electron microscopy and ultraviolet-visible diffuse-reflectance spectroscopy.Under visible-light illumination,a heterogeneous Ag3PO4/Ag/Ag2MoO4 photocatalyst was constructed and demonstrated enhanced photocatalytic activity and photostability compared with pristine Ag3PO4toward the remediation of the organic dye rhodamine B.The Ag3PO4/Ag2MoO4 hybrid catalyst with8%mole fraction of Ag2MoO4 exhibited the highest photocatalytic activity toward the removal of typical dye molecules,including methyl orange,methylene blue and phenol aqueous solution.Moreover,the mechanism of the photocatalytic enhancement was investigated via hole- and radical-trapping experiments,photocurrent measurements,electrochemical impedance spectroscopy and XRD measurements.The XRD analysis revealed that metallic Ag nanoparticles formed initially on the surface of the Ag3PO4/Ag2MoO4 composites under visible-light illumination,leading to the generation of a Ag3PO4/Ag/Ag2MoO4 Z-scheme tandem photocatalytic system.The enhanced photocatalytic activity and stability were attributed to the formation of the Ag3PO4/Ag/Ag2MoO4Z-scheme heterojunction and surface plasmon resonance of photo-reduced Ag nanoparticles on the surface.Finally,a plasmonic Z-scheme photocatalytic mechanism was proposed.This work may provide new insights into the design and preparation of advanced visible-light photocatalytic materials and facilitate their practical application in environmental issues.
基金Projects (60906002, 50832006) supported by the National Natural Science Foundation of ChinaProject (2009QNA4007) supported by the Fundamental Research Funds for the Central Universities, China
文摘The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively coupled plasma mass spectrometry and microwave photo-conductance decay. It is found that the behaviors of Cu precipitation are strongly dependent on the defect density. Most of the Cu contaminants tend to form precipitates homogeneously in the low density defect region, while they mostly segregate at the defects and form precipitates heterogeneously in the high density defect region. In the case of heavy contamination, the Cu precipitate can significantly reduce the carrier lifetime of multicrystalline silicon due to their Schottkydiode behavior in the silicon substrate. A 900 °C rap thermal process （RTP） phosphorus gettering anneal cannot be sufficiently effective to remove the Cu precipitates in these two regions.
文摘We report the performance of the first self-aligned InP/InGaAs double heterojunction bipolar transistor （DHBT） produced in China. The device has a 2μm × 12μm U-shaped emitter area and demonstrates a peak common-emitter DC current gain of over 300,an offset voltage of 0. 16V,a knee voltage of 0.6V,and an open-base breakdown voltage of about 6V. The HBT exhibits good microwave performance with a current gain cutoff fre- quency of 80GHz and a maximum oscillation frequency of 40GHz. These results indicate that this InP/InGaAs DHBT is suitable for low-voltage, low-power, and high-frequency applications.
基金Project (50321402) supported by the National Natural Science Foundation of China project(2004CB619204) supported by Major State Basic Research Development Program of China
文摘Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.
文摘The present work is focused on the relationship between effective segregation coefficient keff and tem- perature of melting zone for purification of phosphorus by zone melting method. Values of keff at four temperatures of melting zone are obtained for zone pass n = 1 at travel velocity of molten zone v = 5x 10^-3 m. h^-1 and initial impu- rity concentration C0〈10 μg.g-1, lnkeff is a linear function of 1/T. The keff values of A1, Ca, Cr, Fe, Cd and Sb in- crease with temperatures while that of Mg is almost constant. The purification is acceptable at lower temperature of melting zone such as 323 K. The variations of enthalpy and entropy between impurities and phosphorus in the liq- uid and solid ohases are also 19resented.
基金Supported by the National Natural Science Foundation of China (No. 29976033) and the State Key Basic Science Research Project (G20000264).
文摘Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution atroom temperature. Conductivity of the composite membranes scatters around 10-3 S.cm-1 at room temperature.The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion117 membrane.
基金Supported by the Eleventh Five-year National Key Technology Research and Development Program of China (2007BAE58B01)
文摘The equilibrium distribution coefficients of 12 impurities （As,Fe,Ca,Co,Al,Cr,Cu,Mg,Mn,Ni,Pb,Zn） in phosphorus were obtained by measuring their effective distribution coefficients at zone travel rate of 3,5,10,15,and 20 mm·h-1 in the purification process with vertical zone-melting technique.The results indicate that the method is reliable.The equilibrium distribution coefficients are below 0.3 except arsenic.
基金the phosphate Esfordi MineShahrood University of Technology for their support during this research
文摘This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impurities. The effects of pulp pH, solid content, reagents dosage(depressant, collector and co-collector) and conditioning time were investigated on the ratio of the modified rate constant of phosphate to the modified rate constant of iron(relative floatability). The results showed that a large dosage of depressant associated with a low value of collector resulted in a better relative floatability. Increasing the co-collector dosage, conditioning time and pH increased the relative floatability up to a certain value and thereafter resulted in diminishing the relative floatability. Meanwhile, the results indicated that increment of solid concentration increased the relative floatability in range investigated. It was also found that that maximum relative floatability(16.05) could be obtained in pulp pH, 9.32, solid percentage, 30,depressant dosage, 440 g/t, collector dosage, 560 g/t, co-collector dosage, 84.63 g/t and conditioning time,9.43 min.
基金supported by the Fundamental Research Funds for the Central Universities
文摘The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chemical vapor deposition(PECVD) at various substrate temperatures.Raman spectroscopy and Fourier transform infrared(FTIR) spectroscopy were used to evaluate the structural evolution,meanwhile,electronic-spin resonance(ESR) and optical measurement were applied to explore the electronic properties of P-doped a-Si:H thin films.The results revealed that the changes in materials structure affect directly the electronic properties and the doping efficiency of dopant.
