A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanat...A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solution. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times.展开更多
Highly active Ir‐La‐S/AC catalyst was successfully prepared by co‐impregnation of an activated carbon（AC） carrier with a sulfuric acid solution of Ir and La species and compared with a tradition‐ally prepared Ir...Highly active Ir‐La‐S/AC catalyst was successfully prepared by co‐impregnation of an activated carbon（AC） carrier with a sulfuric acid solution of Ir and La species and compared with a tradition‐ally prepared Ir‐La/AC catalyst. High angle annular dark‐field‐scanning transmission electron mi‐croscopy（HAADF‐STEM） measurement results show that most of the Ir species on Ir‐La‐S/AC exist as single atomic sites, while those on Ir‐La/AC exist as nanoparticles with an average diameter of 1.5 nm. Evaluation of Ir‐La‐S/AC as a catalyst for heterogeneous carbonylation of methanol to acetyl gave a maximum TOF （turn‐over‐frequency） of 2760 h^–1, which was distinctly higher than that achieved by the Ir‐La/AC catalyst（approximately 1000 h^-1）. Temperature‐programmed desorption of ammonia（NH3‐TPD） result shows that the addition of sulfuric acid during the preparation pro‐cedure results in significantly more acidic sites on Ir‐La‐S/AC than those on Ir‐La/AC, which plays a key role in the enhancement of CO insertion as the rate‐determining step. Tempera‐ture‐programmed reduction（TPR） and in situ X‐ray photoelectron spectroscopy reveal that Ir spe‐cies are more reducible, and that more Ir^＋ might be formed by activation of Ir‐La‐S/AC than those on the Ir‐La/AC catalyst, which is thought to be beneficial for reductive elimination of AcI from Ir^3＋ species as an essential step for CH3I regeneration and acetyl formation.展开更多
Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched long chain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari- ous...Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched long chain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari- ous aspects including better reaction yield and higher purity of the product.The behaviour of the mono(2-butyloctyl)esters and mono(2-methyldodecyl)esters of both phenyl-and o-methylphenylphosphonic acids thus obtained in extraction of lanthanum,praseodymium,neodymium and lutecium as representatives of light and heavy rare earths,is investigated and discussed on the basis of their chemical structure.The dependence of the extraction constants and separation factors accords with the Reactivity-Selectivity Principle in solvent ex- traction proposed by us.The composition and structure of the extracted species have been characterized by infra-red and proton nuclear magnetic resonance spectroscopy in addition to elemental analyses.展开更多
Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability o...Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.展开更多
Eco-friendly SnTe based thermoelectric materials are intensively studied recently as candidates to replace PbTe;yet the thermoelectric performance of SnTe is suppressed by its intrinsically high carrier concentration ...Eco-friendly SnTe based thermoelectric materials are intensively studied recently as candidates to replace PbTe;yet the thermoelectric performance of SnTe is suppressed by its intrinsically high carrier concentration and high thermal conductivity.In this work,we confirm that the Ag and La co-doping can be applied to simultaneously enhance the power factor and reduce the thermal conductivity,contributing to a final promotion of figure of merit.On one hand,the carrier concentration and band offset between valence bands are concurrently reduced,promoting the power factor to a highest value of-2436μW·m^(-1)·K^(-2) at 873 K.On the other hand,lots of dislocations(~3.16×10^(7)mm^(-2))associated with impurity precipitates are generated,resulting in the decline of thermal conductivity to a minimum value of 1.87 W·m^(-1)·K^(-1) at 873 K.As a result,a substantial thermoelectric performance enhancement up to zT≈1.0 at 873 K is obtained for the sample Sn0.94Ag0.09La0.05Te,which is twice that of the pristine SnTe(zT≈0.49 at 873 K).This strategy of synergistic manipulation of electronic band and microstructures via introducing rare earth elements could be applied to other systems to improve thermoelectric performance.展开更多
Doped lead-zirconate-titanate(PZT)thin films are preferred for the development of micro-electro-mechanical systems(MEMS)-based acoustic sensors because of their inherent higher dielectric and piezoelectric coefficient...Doped lead-zirconate-titanate(PZT)thin films are preferred for the development of micro-electro-mechanical systems(MEMS)-based acoustic sensors because of their inherent higher dielectric and piezoelectric coefficients.Patterning process is used to develop such MEMS devices which is highly complex even for undoped PZT thin films;therefore,the problem is further cumbersome for doped PZT thin films due to the presence of added dopant elements and their associated chemistry.This paper presents patterning of strontium(Sr)and lanthanum(La)co-doped PZT thin film(PSLZT)deposited on platinized silicon substrate using wet and dry etching processes for fabricating a diaphragm structure with thickness of 15-25μm and diameter of 1.4-2 mm,suitable for acoustic sensing applications.The effects of various etching conditions have been studied and the results are reported.It is found that the dry etching is the most suited process for realizing the piezoelectric MEMS structure due to its higher etching resolution.An appreciable etching rate of 260-270 nm/min with smooth vertical sidewalls is achieved.The silicon diaphragm with patterned PSLZT thin film is found to retain more than 80%of its dielectric and piezoelectric coefficients and has a resonance of 1.43 MHz.展开更多
We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of-33.8 dBm and a gain coefficient of 1.9 dB/m.With the utilization of the fiber as a gain medium,a linear-cavity fiber lase...We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of-33.8 dBm and a gain coefficient of 1.9 dB/m.With the utilization of the fiber as a gain medium,a linear-cavity fiber laser has been constructed,which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm.It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW,a slope efficiency of up to 17.0%,and a linewidth of less than 0.02 nm.Moreover,an all-fiber single-stage optical amplifier is built up for laser amplification,by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%.The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth,with potential applications for optical fiber sensing,biomedicine,precision measurement,and the pump source of the mid-infrared fiber lasers.展开更多
文摘A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solution. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times.
基金supported by the National Key R&D Program of China (2017YFB0602203)~~
文摘Highly active Ir‐La‐S/AC catalyst was successfully prepared by co‐impregnation of an activated carbon（AC） carrier with a sulfuric acid solution of Ir and La species and compared with a tradition‐ally prepared Ir‐La/AC catalyst. High angle annular dark‐field‐scanning transmission electron mi‐croscopy（HAADF‐STEM） measurement results show that most of the Ir species on Ir‐La‐S/AC exist as single atomic sites, while those on Ir‐La/AC exist as nanoparticles with an average diameter of 1.5 nm. Evaluation of Ir‐La‐S/AC as a catalyst for heterogeneous carbonylation of methanol to acetyl gave a maximum TOF （turn‐over‐frequency） of 2760 h^–1, which was distinctly higher than that achieved by the Ir‐La/AC catalyst（approximately 1000 h^-1）. Temperature‐programmed desorption of ammonia（NH3‐TPD） result shows that the addition of sulfuric acid during the preparation pro‐cedure results in significantly more acidic sites on Ir‐La‐S/AC than those on Ir‐La/AC, which plays a key role in the enhancement of CO insertion as the rate‐determining step. Tempera‐ture‐programmed reduction（TPR） and in situ X‐ray photoelectron spectroscopy reveal that Ir spe‐cies are more reducible, and that more Ir^＋ might be formed by activation of Ir‐La‐S/AC than those on the Ir‐La/AC catalyst, which is thought to be beneficial for reductive elimination of AcI from Ir^3＋ species as an essential step for CH3I regeneration and acetyl formation.
基金supported by the National Natural Science Foundation of China
文摘Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched long chain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari- ous aspects including better reaction yield and higher purity of the product.The behaviour of the mono(2-butyloctyl)esters and mono(2-methyldodecyl)esters of both phenyl-and o-methylphenylphosphonic acids thus obtained in extraction of lanthanum,praseodymium,neodymium and lutecium as representatives of light and heavy rare earths,is investigated and discussed on the basis of their chemical structure.The dependence of the extraction constants and separation factors accords with the Reactivity-Selectivity Principle in solvent ex- traction proposed by us.The composition and structure of the extracted species have been characterized by infra-red and proton nuclear magnetic resonance spectroscopy in addition to elemental analyses.
基金This work is financially supported by the National Natural Science Foundation of China(NSFC,contract no.21875154 and 21473120)The authors also thank the Ministry of Science and Technology of the People's Republic of China,China(Contract No.2015AA034601).
文摘Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.
基金supported by National Natural Science Foundation of China(Grant Nos.51801040,51961011,51772056)Guangxi Natural Science Foundation of China(Grant Nos.2020GXNSFAA159111,AD20159006,2018GXNSFAA294135,2018JJA160257,and 2019GXNSFBA245028).
文摘Eco-friendly SnTe based thermoelectric materials are intensively studied recently as candidates to replace PbTe;yet the thermoelectric performance of SnTe is suppressed by its intrinsically high carrier concentration and high thermal conductivity.In this work,we confirm that the Ag and La co-doping can be applied to simultaneously enhance the power factor and reduce the thermal conductivity,contributing to a final promotion of figure of merit.On one hand,the carrier concentration and band offset between valence bands are concurrently reduced,promoting the power factor to a highest value of-2436μW·m^(-1)·K^(-2) at 873 K.On the other hand,lots of dislocations(~3.16×10^(7)mm^(-2))associated with impurity precipitates are generated,resulting in the decline of thermal conductivity to a minimum value of 1.87 W·m^(-1)·K^(-1) at 873 K.As a result,a substantial thermoelectric performance enhancement up to zT≈1.0 at 873 K is obtained for the sample Sn0.94Ag0.09La0.05Te,which is twice that of the pristine SnTe(zT≈0.49 at 873 K).This strategy of synergistic manipulation of electronic band and microstructures via introducing rare earth elements could be applied to other systems to improve thermoelectric performance.
文摘Doped lead-zirconate-titanate(PZT)thin films are preferred for the development of micro-electro-mechanical systems(MEMS)-based acoustic sensors because of their inherent higher dielectric and piezoelectric coefficients.Patterning process is used to develop such MEMS devices which is highly complex even for undoped PZT thin films;therefore,the problem is further cumbersome for doped PZT thin films due to the presence of added dopant elements and their associated chemistry.This paper presents patterning of strontium(Sr)and lanthanum(La)co-doped PZT thin film(PSLZT)deposited on platinized silicon substrate using wet and dry etching processes for fabricating a diaphragm structure with thickness of 15-25μm and diameter of 1.4-2 mm,suitable for acoustic sensing applications.The effects of various etching conditions have been studied and the results are reported.It is found that the dry etching is the most suited process for realizing the piezoelectric MEMS structure due to its higher etching resolution.An appreciable etching rate of 260-270 nm/min with smooth vertical sidewalls is achieved.The silicon diaphragm with patterned PSLZT thin film is found to retain more than 80%of its dielectric and piezoelectric coefficients and has a resonance of 1.43 MHz.
基金This work was supported by the National Key Research and Development Program of China(No.2020YFB1805800)National Natural Science Foundation of China(Nos.61975113,61935002,61735009,and 61705126),Project(No.D20031)Shanghai Professional Technical Public Service Platform of Advanced Optical Waveguide Intelligent Manufacturing and Testing(No.19DZ2294000).
文摘We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of-33.8 dBm and a gain coefficient of 1.9 dB/m.With the utilization of the fiber as a gain medium,a linear-cavity fiber laser has been constructed,which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm.It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW,a slope efficiency of up to 17.0%,and a linewidth of less than 0.02 nm.Moreover,an all-fiber single-stage optical amplifier is built up for laser amplification,by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%.The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth,with potential applications for optical fiber sensing,biomedicine,precision measurement,and the pump source of the mid-infrared fiber lasers.
