The tobacco leaves were treated with low-temperature plasma in Ar, N2, O2, and air atmospheres at different powers (60―130 W). The surface-elemental components, their relative contents, and the functional groups of t...The tobacco leaves were treated with low-temperature plasma in Ar, N2, O2, and air atmospheres at different powers (60―130 W). The surface-elemental components, their relative contents, and the functional groups of the surface components of the tobacco leaves were determined using XPS (X-ray photoelectron spectroscopy). The ex- perimental results showed that the percentage of the elements C, N, and O had changed considerably and a large number of polar functional groups containing oxygen atoms were incorporated into the components on the tobacco surfaces. The measurements of the surface contact angle showed that the surface contact angle of the modified tobacco leaves was 0 degree, whereas it was 110 degrees before the plasma treatment. These results indicate that the wettability of the modified tobacco leaves improved dramatically. This work may be significant for future researches on the surface modification of the tobacco leaves.展开更多
The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d c...The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples,even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix,which leads to a different nucleation rate of the Ag clusters.展开更多
In this work, we investigate the Co-Si reaction, the Co growth mode at room temperature, diffusion be- haviour as well as morphology evolution during annealing on both H-terminated and clean Si(001) and Si(111) sur- f...In this work, we investigate the Co-Si reaction, the Co growth mode at room temperature, diffusion be- haviour as well as morphology evolution during annealing on both H-terminated and clean Si(001) and Si(111) sur- faces. From in-situ X-ray photoelectron spectroscopy (XPS) investigation, “Co-Si” reaction appears to occur on both H-terminated and clean surfaces at room temperature (RT) and the silicide crystallinity is improved upon annealing. Co growth mode on H-terminated Si surfaces occurs in a pseudo layer-by-layer manner while small close-packed is- land growth mode is observed on the clean Si surface. Upon annealing at different temperatures, Co atom concentra- tion decreases versus annealing time, which in part is attributed to Co atoms inward diffusion. The diffusion behav- iour on both types of surfaces demonstrates a similar trend. Morphology study using ex-situ atomic force microscopy (AFM) shows that the islands formed on Si(001) surface after annealing at 700 °C are elongated with growth direc- tions alternate between the two perpendicular [ 110 ] and [110] directions. Triangular islands are observed on Si (111) surface.展开更多
The kinetics and dynamics of photocatalyzed dissociation of ethanol on TiO2(110) sur- face have been studied using the time-dependent and time-resolved femtosecond two-photon photoemission spectroscopy respectively,...The kinetics and dynamics of photocatalyzed dissociation of ethanol on TiO2(110) sur- face have been studied using the time-dependent and time-resolved femtosecond two-photon photoemission spectroscopy respectively, in order to unravel the photochemical properties of ethanol on this prototypical metal oxide surface. By monitoring the time evolution of the photoinduced excited state which is associated with the photocatalyzed dissociation of ethanol on Ti5c sites of Ti02(ll0), the fractal-like kinetics of this surface photocatalytic reaction has been obtgined. The measured photocatalytic dissociation rate on reduced TiO2(l10) is faster than that on the oxidized surface. This is attributed to the larger defect density on the reduced surface which lowers the reaction barrier of the photocatalytic reaction at least methodologically. Possible reasons associated with the defect electrons for the acceleration have been discussed. By performing the interferometric two-pulse corre- lation on ethanol/TiO2(l10) interface, the ultrafast electron dynamics of the excited state has been measured. The analyzed lifetime (24 fs) of the excited state is similar to that on methanol/TiO2(110). The appearance of the excited state provides a channel to mediate the electron transfer between the TiO2 substrate and its environment. Therefore studying its ultrafast electron dynamics may lead to the understanding of the microscopic mechanism of photocatalysis and photoelectrochemical energy conversion on TiO2.展开更多
Carbon black has been widely used in many industrial areas,but it is poor dispersibility in water.In order to improve its dispersibility in water,carbon black was treated by oxygen plasma.Plasma treatment,as one of th...Carbon black has been widely used in many industrial areas,but it is poor dispersibility in water.In order to improve its dispersibility in water,carbon black was treated by oxygen plasma.Plasma treatment,as one of the environmental friendly methods,has been used to introduce polar groups,mainly oxygen-containing groups,to the surface of carbon black.The results show the dispersibility of treated carbon black in water is greatly improved,which is expressed with the centrifugal and gravity settlement rates.Analysis of the treated carbon black with X-ray photoelectron spectroscopy(XPS)indicates that oxygen plasma treatment can cause significant increase of polar groups including C-OH,COOH,CO,and O-C-O on the surface of carbon black thus greatly improves the dispersing stability of carbon black in water.Besides,the dispersibility of plasma treated carbon black can be further improved by the addition of organic amines,especially polyetheramines.The improvement of the dispersing stability of carbon black has also been confirmed by zeta potential measurements.展开更多
The polystyrene supported phenylalanine Schiff base complex of Mn(Ⅱ) (PS-Sal-Phe-Mn ) was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese (Ⅱ) acetate tetrahyrate., The pol...The polystyrene supported phenylalanine Schiff base complex of Mn(Ⅱ) (PS-Sal-Phe-Mn ) was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese (Ⅱ) acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT.IR,, small area X-ray photoelectron spectroscopy (XPS), and ICP-AES. in the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2.cyclohexen-l-ol (2), 2-cyclohexen-l-one (3)and 2-cyclohexen-1-hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.展开更多
The surface morphology of alloy layer of tinplate was studied by means of scanning electron microscopy. By using the layer on layer debonding technology of glow discharge spectrum, the contents of C and O at the bound...The surface morphology of alloy layer of tinplate was studied by means of scanning electron microscopy. By using the layer on layer debonding technology of glow discharge spectrum, the contents of C and O at the boundary of alloy layer and black plate were analyzed. And the corrosion characteristic of cavity of tinplate alloy layer was studied on-line and in-situ by means of electrochemical atomic force microscope. The corrosion depth of cavity of alloy layer in-situ after different corrosion time was measured. The results show that the cavity of alloy layer is a critical factor causing rapid decline of corrosion resistance of tinplate, and the formation of cavity of alloy layer is due to incorrect pretreatment of black plate before electrotinning. The cavity of alloy layer is the internal factor causing pitting corrosion of tinplate when the tinplate is applied to food packaging material. And the dynamic equation of pitting corrosion generated in the cavity of alloy layer conforms to logarithm law.展开更多
Optical microscopy, and scanning electron microscopy in conjunction with energy dispersed X-ray spectrometry (SEM-EDX), have been used to study the minerals and the concentrations of 12 trace elements in the No.14 c...Optical microscopy, and scanning electron microscopy in conjunction with energy dispersed X-ray spectrometry (SEM-EDX), have been used to study the minerals and the concentrations of 12 trace elements in the No.14 coal from the Huolinhe mine, Inner Mongolia China. The distribution, affinity and removability of the trace elements were studied by float-sink experiments and petrological methods. A high mineral content, dominated by clay minerals, was found in the No.14 coal from the Huolinhe mine. The concentrations of As, Sb and Hg are relatively high compared to the average values for Chinese coals. As, Cr, Hg, Li, Mn, Pb are mainly associated with the minerals while Cd, Co, Ni, Sb, and Se are evenly distributed between the minerals and the organic matter. Be and Ba are mainly distributed in the minerals with a minor proportion in the organic matter. Most elements have a low organic affinity, although Sb, Se, Co, Cd, Ni are closely integrated with the organic matter. High theoretical removabilities are indicated for most trace elements. So it may be possible to lower the concentrations of trace elements during coal preparation.展开更多
A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^* level. Based on the optimized geometries, the electronic, fluorescent and ...A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^* level. Based on the optimized geometries, the electronic, fluorescent and 13C NMR spectra are calculated with INDO/CIS, CIS-ZINDO TD, and B3LYP/6-31G^* methods, respectively. Starting with the first of the series, the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra are blue-shifted owing to the large steric effect of naphthyl rings. On the contrary, the energy gaps of the derivatives turn narrow, and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system. The chemical shifts of sp^2-C on the phenyl rings are moved upfield, while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups.展开更多
Orderly mesoporous CuFe2O4spinel-type mixed oxide with high specific surface area was prepared successfully by a hard-template method in which KIT-6mesoporous silica was selected as the hard template.The KIT-6 hard te...Orderly mesoporous CuFe2O4spinel-type mixed oxide with high specific surface area was prepared successfully by a hard-template method in which KIT-6mesoporous silica was selected as the hard template.The KIT-6 hard template and CuFe2O4samples were characterized by X-ray diffraction,X-ray photoelectron spectroscopy,X-ray fluorescence,transmission electron microscopy,scanning electron microscopy,nitrogen physisorption,and hydrogen-temperature programmed reduction.The KIT-6 hard template had perfect crystallization and ordered mesoporous structure with a probable pore distribution of about 9.1 nm,large enough to be filled by the spinel precursor.The mesoporous CuFe2O4spinel oxide synthesized inside the KIT-6 mesopores had a relatively small pore size(4.3 nm),orderly arrangement,and high specific area(194 m2/g).The catalytic activity of the mesoporous CuFe2O4was tested for the selective oxidation of ammonia to nitrogen.The conversion of ammonia reached nearly 100%at 300°C with a nitrogen selectivity as high as 96%.The nitrogen selectivity remained high with increasing temperature and even maintained a value of80%at 600°C.展开更多
We report for the first time the preparation method of compact TiO2 film using titanium butoxide-petroleum ether solution, by means of dipping and sintering. Our estimation of the component of this thin film was confi...We report for the first time the preparation method of compact TiO2 film using titanium butoxide-petroleum ether solution, by means of dipping and sintering. Our estimation of the component of this thin film was confirmed by XPS test. Studies of AFM showed the influence of preparation condition upon surface morphology. The transmitted spectrum of this compact TiO2 film was also investigated, which presented an excellent transmittance of this film in the visible light region. We arrive at a conclusion,according to the I-V characteristics of solid-state Grǎitzel solar cells utilizing this kind of compact film, that this compact TiO2 film functions well in secluding the conducting substrate from the hole-conducting material.展开更多
This paper reports the effects of long- distance and direct argon radio frequency (RF) plasma surface treatment on polyvinyl chloride (PVC) films in terms of changes in surface wettability and surface chemistry. The s...This paper reports the effects of long- distance and direct argon radio frequency (RF) plasma surface treatment on polyvinyl chloride (PVC) films in terms of changes in surface wettability and surface chemistry. The surface properties are char- acterized by the water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scan- ning electron microscopy (SEM). The mechanism is further analyzed and the role of all kinds of active species, e.g. electrons, ions and free radicals in- volved in plasma surface modification is further evaluated. Results show that the long-distance and direct RF plasma treatments modify the PVC surface in morphology and composition, and both modifica- tions cause surface oxidation of PVC films, in the forming of functional groups enhancing polymer wet- tability. The effect of the long-distance argon RF plasma is more notable. This suggests that long-distance argon RF plasma could restrain the ion and electron eroding effect and enhance free radical reaction.展开更多
Globin-like mesoporous CeO2 has been constructed by using a CO-assisted synthetic approach based on hydroxide carbonate precursors, in which CO plays a key role in the formation of the globin-like mesoporous precursor...Globin-like mesoporous CeO2 has been constructed by using a CO-assisted synthetic approach based on hydroxide carbonate precursors, in which CO plays a key role in the formation of the globin-like mesoporous precursors as the carbon source because of its preferential adsorption on Ce^3+ under the hydrothermal conditions. The formation mechanism and the thermal transformation process from globin-like mesoporous CeCO3OH to CeO2 have been investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, BET surface area measurements, thermal analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and X-ray photoelectron spec- troscopy. Rod-like building blocks interconnected by nanoparticles circle around to form each globin-like CeO2 spheres, leading to the formation of a mesoporous structure. The globin-like mesoporous CeO2 shows much better performance in CO catalytic oxidation than ordinary CeO2 nanoparticles obtained by directly calcining cerium nitrate. Moreover, the globin-like mesoporous CeO2 can act as an ideal matrix for supported catalysts. Metallic Au particles can be well dispersed in the globin-like CeO2 matrix to form Au/CeO2 supported catalysts, which exhibit excellent activity for CO oxidation at room temperature.展开更多
Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering.The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the dep...Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering.The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied.The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film.When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa,the x value is approximately 1 and the valence of nickel is +2.At this point,NiOx is antiferromagnetic NiO and the corresponding Hex is the largest.As the ratio of Ar/O2 deviates from 7,the exchange coupling field (Hex) will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx/NiFe,while the coercivity (Hc) will increase due to the metallic Ni.XPS studies also show that there are two thermodynamically favorable reactions at the NiO/NiFe interface: NiO+Fe=Ni+FeO and 3NiO+2Fe=3Ni+Fe2O3.These interface reaction products are magnetic impurities at the interface region of NiO/NiFe.It is believed that these magnetic impurities would have effect on the exchange coupling field (Hex) and the coercivity (Hc) of NiO/NiFe.展开更多
In this work, we study the interlayer phonon vibration modes, the layer-number- dependent optical bandgap, and the anisotropic photoluminescence (PL) spectra of atomically thin rhenium diselenide (ReSe2) for the f...In this work, we study the interlayer phonon vibration modes, the layer-number- dependent optical bandgap, and the anisotropic photoluminescence (PL) spectra of atomically thin rhenium diselenide (ReSe2) for the first time. The ultralow frequency interlayer Raman spectra and the polarization-resolved high frequency Raman spectra in ReSe2 allow the identification of its layer number and crystal orientation. Furthermore, PL measurements show the anisotropic optical emission intensity of the material with its bandgap increasing from 1.26 eV in the bulk to 1.32 eV in the monolayer. The study of the layer-number dependence of the Raman modes and the PL spectra reveals relatively weak van der Waal's interaction and two-dimensional (2D) quantum confinement in the atomically thin ReSe2. The experimental observation of the intriguing anisotropic interlayer interaction and tunable optical transition in monolayer and multilayer ReSe2 establishes the foundation for further exploration of this material in the development of anisotropic optoelectronic devices functioning in the near-infrared spectrum, which is important for many applications in optical communication and infrared sensing,展开更多
Three-dimensional (3D) hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along (111, 110),...Three-dimensional (3D) hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along (111, 110), (111), and (100) planes, respectively. These structures have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma optical emission spectrometry (ICP-OES) and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.展开更多
Benefiting from the development of molecular electronics and molecular plasmonics, the interplay of light and electronic transport in molecular junctions has attracted growing interest among researchers in both fields...Benefiting from the development of molecular electronics and molecular plasmonics, the interplay of light and electronic transport in molecular junctions has attracted growing interest among researchers in both fields, leading to a new research direction of "single-molecule optoelectronics". Here, we review the latest developments of photo-modulated charge transport,electroluminescence and Raman spectroscopy from single-molecule junctions, and suggest future directions for single-molecule optoelectronics.展开更多
Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Har...Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.展开更多
基金Supported by Research Fund of Monopoly Administration of Tobacco of China (No. 110200201016)
文摘The tobacco leaves were treated with low-temperature plasma in Ar, N2, O2, and air atmospheres at different powers (60―130 W). The surface-elemental components, their relative contents, and the functional groups of the surface components of the tobacco leaves were determined using XPS (X-ray photoelectron spectroscopy). The ex- perimental results showed that the percentage of the elements C, N, and O had changed considerably and a large number of polar functional groups containing oxygen atoms were incorporated into the components on the tobacco surfaces. The measurements of the surface contact angle showed that the surface contact angle of the modified tobacco leaves was 0 degree, whereas it was 110 degrees before the plasma treatment. These results indicate that the wettability of the modified tobacco leaves improved dramatically. This work may be significant for future researches on the surface modification of the tobacco leaves.
基金This work was partially supported by MIUR-FIRB (RBNE012N3X-005) and by PAT-FAPVU projects.
文摘The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples,even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix,which leads to a different nucleation rate of the Ag clusters.
文摘In this work, we investigate the Co-Si reaction, the Co growth mode at room temperature, diffusion be- haviour as well as morphology evolution during annealing on both H-terminated and clean Si(001) and Si(111) sur- faces. From in-situ X-ray photoelectron spectroscopy (XPS) investigation, “Co-Si” reaction appears to occur on both H-terminated and clean surfaces at room temperature (RT) and the silicide crystallinity is improved upon annealing. Co growth mode on H-terminated Si surfaces occurs in a pseudo layer-by-layer manner while small close-packed is- land growth mode is observed on the clean Si surface. Upon annealing at different temperatures, Co atom concentra- tion decreases versus annealing time, which in part is attributed to Co atoms inward diffusion. The diffusion behav- iour on both types of surfaces demonstrates a similar trend. Morphology study using ex-situ atomic force microscopy (AFM) shows that the islands formed on Si(001) surface after annealing at 700 °C are elongated with growth direc- tions alternate between the two perpendicular [ 110 ] and [110] directions. Triangular islands are observed on Si (111) surface.
文摘The kinetics and dynamics of photocatalyzed dissociation of ethanol on TiO2(110) sur- face have been studied using the time-dependent and time-resolved femtosecond two-photon photoemission spectroscopy respectively, in order to unravel the photochemical properties of ethanol on this prototypical metal oxide surface. By monitoring the time evolution of the photoinduced excited state which is associated with the photocatalyzed dissociation of ethanol on Ti5c sites of Ti02(ll0), the fractal-like kinetics of this surface photocatalytic reaction has been obtgined. The measured photocatalytic dissociation rate on reduced TiO2(l10) is faster than that on the oxidized surface. This is attributed to the larger defect density on the reduced surface which lowers the reaction barrier of the photocatalytic reaction at least methodologically. Possible reasons associated with the defect electrons for the acceleration have been discussed. By performing the interferometric two-pulse corre- lation on ethanol/TiO2(l10) interface, the ultrafast electron dynamics of the excited state has been measured. The analyzed lifetime (24 fs) of the excited state is similar to that on methanol/TiO2(110). The appearance of the excited state provides a channel to mediate the electron transfer between the TiO2 substrate and its environment. Therefore studying its ultrafast electron dynamics may lead to the understanding of the microscopic mechanism of photocatalysis and photoelectrochemical energy conversion on TiO2.
基金Program for Changjiang Scholars and Innovative Research Teamin University,China(No.IRT0526)
文摘Carbon black has been widely used in many industrial areas,but it is poor dispersibility in water.In order to improve its dispersibility in water,carbon black was treated by oxygen plasma.Plasma treatment,as one of the environmental friendly methods,has been used to introduce polar groups,mainly oxygen-containing groups,to the surface of carbon black.The results show the dispersibility of treated carbon black in water is greatly improved,which is expressed with the centrifugal and gravity settlement rates.Analysis of the treated carbon black with X-ray photoelectron spectroscopy(XPS)indicates that oxygen plasma treatment can cause significant increase of polar groups including C-OH,COOH,CO,and O-C-O on the surface of carbon black thus greatly improves the dispersing stability of carbon black in water.Besides,the dispersibility of plasma treated carbon black can be further improved by the addition of organic amines,especially polyetheramines.The improvement of the dispersing stability of carbon black has also been confirmed by zeta potential measurements.
文摘The polystyrene supported phenylalanine Schiff base complex of Mn(Ⅱ) (PS-Sal-Phe-Mn ) was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese (Ⅱ) acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT.IR,, small area X-ray photoelectron spectroscopy (XPS), and ICP-AES. in the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2.cyclohexen-l-ol (2), 2-cyclohexen-l-one (3)and 2-cyclohexen-1-hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.
文摘The surface morphology of alloy layer of tinplate was studied by means of scanning electron microscopy. By using the layer on layer debonding technology of glow discharge spectrum, the contents of C and O at the boundary of alloy layer and black plate were analyzed. And the corrosion characteristic of cavity of tinplate alloy layer was studied on-line and in-situ by means of electrochemical atomic force microscope. The corrosion depth of cavity of alloy layer in-situ after different corrosion time was measured. The results show that the cavity of alloy layer is a critical factor causing rapid decline of corrosion resistance of tinplate, and the formation of cavity of alloy layer is due to incorrect pretreatment of black plate before electrotinning. The cavity of alloy layer is the internal factor causing pitting corrosion of tinplate when the tinplate is applied to food packaging material. And the dynamic equation of pitting corrosion generated in the cavity of alloy layer conforms to logarithm law.
文摘Optical microscopy, and scanning electron microscopy in conjunction with energy dispersed X-ray spectrometry (SEM-EDX), have been used to study the minerals and the concentrations of 12 trace elements in the No.14 coal from the Huolinhe mine, Inner Mongolia China. The distribution, affinity and removability of the trace elements were studied by float-sink experiments and petrological methods. A high mineral content, dominated by clay minerals, was found in the No.14 coal from the Huolinhe mine. The concentrations of As, Sb and Hg are relatively high compared to the average values for Chinese coals. As, Cr, Hg, Li, Mn, Pb are mainly associated with the minerals while Cd, Co, Ni, Sb, and Se are evenly distributed between the minerals and the organic matter. Be and Ba are mainly distributed in the minerals with a minor proportion in the organic matter. Most elements have a low organic affinity, although Sb, Se, Co, Cd, Ni are closely integrated with the organic matter. High theoretical removabilities are indicated for most trace elements. So it may be possible to lower the concentrations of trace elements during coal preparation.
文摘A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^* level. Based on the optimized geometries, the electronic, fluorescent and 13C NMR spectra are calculated with INDO/CIS, CIS-ZINDO TD, and B3LYP/6-31G^* methods, respectively. Starting with the first of the series, the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra are blue-shifted owing to the large steric effect of naphthyl rings. On the contrary, the energy gaps of the derivatives turn narrow, and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system. The chemical shifts of sp^2-C on the phenyl rings are moved upfield, while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups.
基金supported by the National High Technology Research and Development Program of China (2013AA065900)the National Natural Science Foundation of China (21177008,21121064)
文摘Orderly mesoporous CuFe2O4spinel-type mixed oxide with high specific surface area was prepared successfully by a hard-template method in which KIT-6mesoporous silica was selected as the hard template.The KIT-6 hard template and CuFe2O4samples were characterized by X-ray diffraction,X-ray photoelectron spectroscopy,X-ray fluorescence,transmission electron microscopy,scanning electron microscopy,nitrogen physisorption,and hydrogen-temperature programmed reduction.The KIT-6 hard template had perfect crystallization and ordered mesoporous structure with a probable pore distribution of about 9.1 nm,large enough to be filled by the spinel precursor.The mesoporous CuFe2O4spinel oxide synthesized inside the KIT-6 mesopores had a relatively small pore size(4.3 nm),orderly arrangement,and high specific area(194 m2/g).The catalytic activity of the mesoporous CuFe2O4was tested for the selective oxidation of ammonia to nitrogen.The conversion of ammonia reached nearly 100%at 300°C with a nitrogen selectivity as high as 96%.The nitrogen selectivity remained high with increasing temperature and even maintained a value of80%at 600°C.
文摘We report for the first time the preparation method of compact TiO2 film using titanium butoxide-petroleum ether solution, by means of dipping and sintering. Our estimation of the component of this thin film was confirmed by XPS test. Studies of AFM showed the influence of preparation condition upon surface morphology. The transmitted spectrum of this compact TiO2 film was also investigated, which presented an excellent transmittance of this film in the visible light region. We arrive at a conclusion,according to the I-V characteristics of solid-state Grǎitzel solar cells utilizing this kind of compact film, that this compact TiO2 film functions well in secluding the conducting substrate from the hole-conducting material.
基金supported by the National Natural Science Foundation of China(Grant No.20174030)the specialized research Fund for the Doctoral Program of Higher Education(20010698007)the Scientific Research Star Fund for the Study Abroad Returnee and the Key Scientific Technique Item of Shaanxi Province(2001[345]).
文摘This paper reports the effects of long- distance and direct argon radio frequency (RF) plasma surface treatment on polyvinyl chloride (PVC) films in terms of changes in surface wettability and surface chemistry. The surface properties are char- acterized by the water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scan- ning electron microscopy (SEM). The mechanism is further analyzed and the role of all kinds of active species, e.g. electrons, ions and free radicals in- volved in plasma surface modification is further evaluated. Results show that the long-distance and direct RF plasma treatments modify the PVC surface in morphology and composition, and both modifica- tions cause surface oxidation of PVC films, in the forming of functional groups enhancing polymer wet- tability. The effect of the long-distance argon RF plasma is more notable. This suggests that long-distance argon RF plasma could restrain the ion and electron eroding effect and enhance free radical reaction.
文摘Globin-like mesoporous CeO2 has been constructed by using a CO-assisted synthetic approach based on hydroxide carbonate precursors, in which CO plays a key role in the formation of the globin-like mesoporous precursors as the carbon source because of its preferential adsorption on Ce^3+ under the hydrothermal conditions. The formation mechanism and the thermal transformation process from globin-like mesoporous CeCO3OH to CeO2 have been investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, BET surface area measurements, thermal analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and X-ray photoelectron spec- troscopy. Rod-like building blocks interconnected by nanoparticles circle around to form each globin-like CeO2 spheres, leading to the formation of a mesoporous structure. The globin-like mesoporous CeO2 shows much better performance in CO catalytic oxidation than ordinary CeO2 nanoparticles obtained by directly calcining cerium nitrate. Moreover, the globin-like mesoporous CeO2 can act as an ideal matrix for supported catalysts. Metallic Au particles can be well dispersed in the globin-like CeO2 matrix to form Au/CeO2 supported catalysts, which exhibit excellent activity for CO oxidation at room temperature.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19890310) .
文摘Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering.The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied.The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film.When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa,the x value is approximately 1 and the valence of nickel is +2.At this point,NiOx is antiferromagnetic NiO and the corresponding Hex is the largest.As the ratio of Ar/O2 deviates from 7,the exchange coupling field (Hex) will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx/NiFe,while the coercivity (Hc) will increase due to the metallic Ni.XPS studies also show that there are two thermodynamically favorable reactions at the NiO/NiFe interface: NiO+Fe=Ni+FeO and 3NiO+2Fe=3Ni+Fe2O3.These interface reaction products are magnetic impurities at the interface region of NiO/NiFe.It is believed that these magnetic impurities would have effect on the exchange coupling field (Hex) and the coercivity (Hc) of NiO/NiFe.
基金Acknowledgements This work is partially supported by National Science Foundation EFRI 2-DARE program (No. 1542815) and Zumberge Research and Innovation Fund Award. P.-H. Tan acknowledges support from the National Natural Science Foundation of China (Nos. 11225421, 11474277, and 11434010).
文摘In this work, we study the interlayer phonon vibration modes, the layer-number- dependent optical bandgap, and the anisotropic photoluminescence (PL) spectra of atomically thin rhenium diselenide (ReSe2) for the first time. The ultralow frequency interlayer Raman spectra and the polarization-resolved high frequency Raman spectra in ReSe2 allow the identification of its layer number and crystal orientation. Furthermore, PL measurements show the anisotropic optical emission intensity of the material with its bandgap increasing from 1.26 eV in the bulk to 1.32 eV in the monolayer. The study of the layer-number dependence of the Raman modes and the PL spectra reveals relatively weak van der Waal's interaction and two-dimensional (2D) quantum confinement in the atomically thin ReSe2. The experimental observation of the intriguing anisotropic interlayer interaction and tunable optical transition in monolayer and multilayer ReSe2 establishes the foundation for further exploration of this material in the development of anisotropic optoelectronic devices functioning in the near-infrared spectrum, which is important for many applications in optical communication and infrared sensing,
基金This work was supported by the National Natural Science Foundation of China (Nos. 91127040 and 21221062), and the State Key Project of Fundamental Research for Nanoscience and Nanotechnology (No. 2011CB932402).
文摘Three-dimensional (3D) hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along (111, 110), (111), and (100) planes, respectively. These structures have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma optical emission spectrometry (ICP-OES) and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.
基金supported by the National Key R&D Program of China (2017YFA0204901, 2017YFA0204902)the National Natural Science Foundation of China (21673195, 61571242, 21503179, 21727806, 21722305)the Young Thousand Talent Project of China
文摘Benefiting from the development of molecular electronics and molecular plasmonics, the interplay of light and electronic transport in molecular junctions has attracted growing interest among researchers in both fields, leading to a new research direction of "single-molecule optoelectronics". Here, we review the latest developments of photo-modulated charge transport,electroluminescence and Raman spectroscopy from single-molecule junctions, and suggest future directions for single-molecule optoelectronics.
基金supported by the Fonds der Chemischen Industrie and Deutsche Forschungsgemeinschaft (Mu 1088/9-1)
文摘Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.