A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, fol...A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.展开更多
Full-spectrum photofixation of N_(2) with remarkable NH_(3) production rate of 228μmol/(g·h)was achieved by W atoms doped Ti_(3)C_(2)T_(x)MXene(W/Ti_(3)C_(2)T_(x)-U)catalyst without sacrificial agents at room te...Full-spectrum photofixation of N_(2) with remarkable NH_(3) production rate of 228μmol/(g·h)was achieved by W atoms doped Ti_(3)C_(2)T_(x)MXene(W/Ti_(3)C_(2)T_(x)-U)catalyst without sacrificial agents at room temperature.The effects of W doping and ultrasonic intercalation of Ti_(3)C_(2)T_(x)MXene were studied.Scanning transmission electron microscope,electron spin resonance spectra,X-ray photoemission spectroscopy,UV-Vis spectrophotometer,temperature programmed adsorption analyzer and density functional theory calculation were used to characterize the obtained catalysts.Results showed that Ti_(3)C_(2)T_(x)MXene harvested ultraviolet-visible and near-infrared light to generate hot electrons.In addition,the doped W atoms played an effective role in adsorbing and activating N_(2) molecules by donating electrons to the anti-bonding orbital of N_(2) molecules to elongate the bond length of N≡N.展开更多
A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differentia...A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differential scanning calorimetry(TG-DSC),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and FTIR pyridine adsorption.The as-prepared heteropoly acids have a Keggin type structure.The synthesis of tetrahydrofuran by reactive distillation and cyclodehydration of 1,4-butanediol was studied using the tungsten-substituted molybdophosphoric acids as catalysts.The results of catalytic test indicated that the catalytic activity increased with the increase in the substitution number(n) of tungsten atom in H3PMo12-nWnO40·xH2O and was constant as the substitution number(n) was more than 8.The catalytic activity increased with the increase in the catalyst loading and the selectivity of tetrahydrofuran was nearly 100%.展开更多
A new heterometallic cluster W2Ag2S4(tdt)2(PPh3)2·CH2Cl2(H2tdt=H2CH3C6H3S2)(Ⅱ) has been prepared from the reaction of a well-defined molecular building block W2S4(tdt)22-(I) with Ag complex. The compound has bee...A new heterometallic cluster W2Ag2S4(tdt)2(PPh3)2·CH2Cl2(H2tdt=H2CH3C6H3S2)(Ⅱ) has been prepared from the reaction of a well-defined molecular building block W2S4(tdt)22-(I) with Ag complex. The compound has been characterized by X-ray diffraction study, IR., UV-Vis Spectroscopy and cyclic voltammetry.Crystallographic data for the compound are: space group P21/n,a=17.234(4), b=17.622(4), c=19. 094(4) A,β= 99. 22(2)°,V=5704(2) A3, Z=4,final R=0. 042 and Rw=0. 049 for 5983 independent reflections with I≥3σ(I) The structure analysis reveals that the cluster contains a cubane-like core [W2Ag2S4]4+ . The coordination geometry of each tungsten atom is a square pyramid just as that in the building block. Two types of metal-metal bonds of W-W bond and W-Ag bond exist in the core. The distance between two Ag atoms is out of the range of bonding.展开更多
Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the...Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the structure and thermal properties of obtained membranes.The analyses of water uptake,proton conductivity and mechanical properties of the membranes revealed that PWA and silica produced a beneficial effect on proton conduction of the membranes.The membranes with 50 wt% of PWA-SiO2 /PSA were mechanically stable and gave proton conductivity of 2.57×10-2 S·cm-1 at 90℃ and 100% relative humidity.According to the obtained results,PWA and SiO2 doped PSA is a promising material for proton exchange membrane.展开更多
Tungsten oxide （W18O49） nanorods were grown by directly heating tungsten foils covered with potassium bromide （KBr） in low-pressure wet oxygen. The approach featured such advantages as convenient manipulation, low...Tungsten oxide （W18O49） nanorods were grown by directly heating tungsten foils covered with potassium bromide （KBr） in low-pressure wet oxygen. The approach featured such advantages as convenient manipulation, low cost and rapid accessibility to high temperatures. A solid-liquid-solid （SLS） mechanism is believed to have dominated the growth process, in which the W18049 nanorods segregated from eutectic droplets of potassium tungstate and tungsten oxide. The ultraviolet photoelectron spectroscopy （UPS） analysis disclosed that the valence band maximum （VBM） of these nanorods was approximately 9 eV be- low the vacuum level. The feasibility of using the such-fabricated nanorods as field emitters was tested and the related mecha- nism was also discussed.展开更多
文摘介绍了东方超环(experimental advanced supereonducting tokamak, EAST)托卡马克上的两套快速极紫外(EUV)光谱仪系统波长的原位标定方法、结果及其应用。这两套谱仪均为掠入射平场谱仪,时间分辨均为5 ms·frame -1 。两套谱仪分别工作在20~500和10~130 的波段范围,由步进电机控制探测器在焦平面上移动实现整个观测波段上的波长扫描。利用这两套谱仪系统观测极紫外波段光谱,计算EAST中低-高Z杂质离子特征线辐射强度随时间的演化,监测和研究等离子体中杂质的行为。高Z杂质尤其是钨、钼等金属元素,发出的EUV波段光谱的构成非常复杂,准确识谱对谱仪精确的波长测量能力以及谱分辨能力要求很高,因此精确的波长标定是识别钨、钼等高Z杂质谱线以及研究它们行为的最关键的技术之一。利用EAST等离子体中类氢到类铍的低、中Z杂质的特征谱线以及它们的二阶甚至三阶谱线,结合谱仪系统的色散能力,对这两套快速极紫外光谱仪的波长进行了精确的原位标定。用于波长标定的杂质谱线有O Ⅷ 18.97 , O Ⅶ 21.60 , C Ⅵ 33.73 , Li Ⅲ 113.9 , Li Ⅲ 135.0 , Li Ⅱ 199.28 , Ar ⅩⅤ 221.15 , He Ⅱ 256.317 , He Ⅱ 303.78 , Ar ⅩⅥ 353.853 及C Ⅳ 384.174 等。利用波长标定的结果对观测到的EUV光谱进行谱线识别,两套谱仪观测到的绝大多数谱线波长与美国技术标准局(National Institute of Standards and Technology, NIST)数据库的标准波长相差分别小于0.08和0.03 。开发了谱仪波长原位标定程序模块,将这个模块内嵌到谱仪数据实时上传的交互式软件中,实现了全谱数据以及特征谱线强度随时间演化数据的实时处理和上传。同时利用开发的全谱分析交互式软件以及EAST上的数据查看软件,最终实现了快速EUV谱仪自采数据的准实时分析、读取和查看。
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.41373127） and Liaon- ing Provincial Natural Science Foundation of China （No.2013020121）.
文摘A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.
基金supported by the National Natural Science Foundation of China(Nos.51801235,11875258,11505187,51374255,51802356,51572299,41701359)the Natural Science Foundation of Hunan Province,China(No.2020JJ5690)。
文摘Full-spectrum photofixation of N_(2) with remarkable NH_(3) production rate of 228μmol/(g·h)was achieved by W atoms doped Ti_(3)C_(2)T_(x)MXene(W/Ti_(3)C_(2)T_(x)-U)catalyst without sacrificial agents at room temperature.The effects of W doping and ultrasonic intercalation of Ti_(3)C_(2)T_(x)MXene were studied.Scanning transmission electron microscope,electron spin resonance spectra,X-ray photoemission spectroscopy,UV-Vis spectrophotometer,temperature programmed adsorption analyzer and density functional theory calculation were used to characterize the obtained catalysts.Results showed that Ti_(3)C_(2)T_(x)MXene harvested ultraviolet-visible and near-infrared light to generate hot electrons.In addition,the doped W atoms played an effective role in adsorbing and activating N_(2) molecules by donating electrons to the anti-bonding orbital of N_(2) molecules to elongate the bond length of N≡N.
基金Supported by Research Funds from Chinese Education Department (2003406)Bureau of Science and Technology of Jiangsu Province (BG2006025)
文摘A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differential scanning calorimetry(TG-DSC),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and FTIR pyridine adsorption.The as-prepared heteropoly acids have a Keggin type structure.The synthesis of tetrahydrofuran by reactive distillation and cyclodehydration of 1,4-butanediol was studied using the tungsten-substituted molybdophosphoric acids as catalysts.The results of catalytic test indicated that the catalytic activity increased with the increase in the substitution number(n) of tungsten atom in H3PMo12-nWnO40·xH2O and was constant as the substitution number(n) was more than 8.The catalytic activity increased with the increase in the catalyst loading and the selectivity of tetrahydrofuran was nearly 100%.
文摘A new heterometallic cluster W2Ag2S4(tdt)2(PPh3)2·CH2Cl2(H2tdt=H2CH3C6H3S2)(Ⅱ) has been prepared from the reaction of a well-defined molecular building block W2S4(tdt)22-(I) with Ag complex. The compound has been characterized by X-ray diffraction study, IR., UV-Vis Spectroscopy and cyclic voltammetry.Crystallographic data for the compound are: space group P21/n,a=17.234(4), b=17.622(4), c=19. 094(4) A,β= 99. 22(2)°,V=5704(2) A3, Z=4,final R=0. 042 and Rw=0. 049 for 5983 independent reflections with I≥3σ(I) The structure analysis reveals that the cluster contains a cubane-like core [W2Ag2S4]4+ . The coordination geometry of each tungsten atom is a square pyramid just as that in the building block. Two types of metal-metal bonds of W-W bond and W-Ag bond exist in the core. The distance between two Ag atoms is out of the range of bonding.
文摘Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the structure and thermal properties of obtained membranes.The analyses of water uptake,proton conductivity and mechanical properties of the membranes revealed that PWA and silica produced a beneficial effect on proton conduction of the membranes.The membranes with 50 wt% of PWA-SiO2 /PSA were mechanically stable and gave proton conductivity of 2.57×10-2 S·cm-1 at 90℃ and 100% relative humidity.According to the obtained results,PWA and SiO2 doped PSA is a promising material for proton exchange membrane.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61171023,61076057 and 61072025)
文摘Tungsten oxide （W18O49） nanorods were grown by directly heating tungsten foils covered with potassium bromide （KBr） in low-pressure wet oxygen. The approach featured such advantages as convenient manipulation, low cost and rapid accessibility to high temperatures. A solid-liquid-solid （SLS） mechanism is believed to have dominated the growth process, in which the W18049 nanorods segregated from eutectic droplets of potassium tungstate and tungsten oxide. The ultraviolet photoelectron spectroscopy （UPS） analysis disclosed that the valence band maximum （VBM） of these nanorods was approximately 9 eV be- low the vacuum level. The feasibility of using the such-fabricated nanorods as field emitters was tested and the related mecha- nism was also discussed.
