The Ti base PbO 2 electrode prepared by electrodeposition of PbO 2 on the surface of titanium was used for electro catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition...The Ti base PbO 2 electrode prepared by electrodeposition of PbO 2 on the surface of titanium was used for electro catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition of PbO 2 at a higher current density for a short time, then followed by a lower current density can get a compact and combinative PbO 2 layer. The properties of a Ti/PbO 2 electrode with an interlayer of oxide are the best. When this kind of electrode is used to treat phenol containing waste water, the phenol removal rate is higher and the slot voltage is lower. In addition, by using the phenol removal rate as an index, the influences of electrolysis current density, mass transfer condition and pH were studied and the optimal condition was confirmed.展开更多
Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.Ho...Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.展开更多
The performance of a lubricant largely depends on the additives it involves. However, currently used additives cause severe pollution if they are burned and exhausted. Therefore, it is necessary to develop a new gener...The performance of a lubricant largely depends on the additives it involves. However, currently used additives cause severe pollution if they are burned and exhausted. Therefore, it is necessary to develop a new generation of green additives. Graphene oxide（GO） consists of only C, H and O and thus is considered to be environmentally friendly. So the tribological properties of the few-layer GO sheet as an additive in hydrocarbon base oil are investigated systematically. It is found that, with the addition of GO sheets, both the coefficient of friction（COF） and wear are decreased and the working temperature range of the lubricant is expanded in the positive direction. Moreover, GO sheets has better performance under higher sliding speed and the optimized concentration of GO sheets is determined to be 0.5wt%. After rubbing, GO is detected on the wear scars through Raman spectroscopy. And it is believed that, during the rubbing, GO sheets adhere to the sliding surfaces, behaving like protective films and preventing the sliding surfaces from contacting with each other directly. This paper proves that the GO sheet is an effective lubricant additive, illuminates the lubrication mechanism, and provides some critical parameters for the practical application of GO sheets in lubrication.展开更多
Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distribu...Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distributed ranges of the superconductive transition temperature (Tc) for complex oxides, and Tc values for cuprate superconductors. The calculated results indicated that the adjusted ANN can be used to predict superconductive properties for unknown oxides.展开更多
We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-...We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.展开更多
We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electr...We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electrode is relatively thick, the device of the cross-point Al electrode shows a three-level memory effect, and the counterpart device of the cross-bar Al electrode exhibits a volatile static random access memory effect. When the thickness of the AI electrode is thinner, the above devices demonstrate a flash memory effect. The different memory behaviors of ITO/GO/AI diodes are ascribed to the mode and degree of reduction and oxidation of GO.展开更多
Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO ...Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.展开更多
A silica gel supported cobalt（lI） Schiff base complex was synthesized and used for the oxidation of alkyl aromatics using molecular oxygen as an oxidant under atmosphere pressure. The catalyst shows a high conversio...A silica gel supported cobalt（lI） Schiff base complex was synthesized and used for the oxidation of alkyl aromatics using molecular oxygen as an oxidant under atmosphere pressure. The catalyst shows a high conversion of alkyl aromatics and selectivity to benzylic ketones, and could be reused at least 5 times without significant loss of catalytic activity.展开更多
We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber fe...We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber ferrule in the laser cavity. The Ni O-SA shows a 39% modulation depth with a 0.04 MW∕cm^2 saturation intensity. Our ring laser cavity based on erbium-doped active fiber with managed intracavity dispersion has the ability to generate ultrashort pulses with a full width at half-maximum（FWHM） of around 2.85 nm centered at 1561.8 nm.The pulses repeat at a frequency of 0.96 MHz and duration of 950 fs.展开更多
We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets disp...We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets display highly efficient broadband optical limiting activities for femtosecond laser pulses at 400,800,and 1400 nm with very low limiting thresholds.Femtosecond pump–probe measurement results revealed that nonlinear absorption played an important role for the observed optical limiting activities.High flexibility and efficient optical limiting activities of these materials allow these composite sheets to be attached to nonplanar optical sensors in order to protect them from light-induced damage.展开更多
The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- f...The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- filtrated into a PSi device. The results indicate that the intensity of the fluorescence of the GOQD-inflltrated multilayer with a high reflection band located at its fluorescence spectra scope is approximately double that of the single layer sample. This indicates that the multilayer GOQD-infiltrated PSi substrate is a suitable material for the preparation of sensitive photoluminescence biosensors.展开更多
Ceria-zirconia based mixed oxides(CZs)have been applied in three-way catalysts(TWCs)for their high surface area and oxygen storage capacity(OSC).In this work,enhanced thermal stability of Ce_(0.33)Zr_(0.55)(LaNdY)_(0....Ceria-zirconia based mixed oxides(CZs)have been applied in three-way catalysts(TWCs)for their high surface area and oxygen storage capacity(OSC).In this work,enhanced thermal stability of Ce_(0.33)Zr_(0.55)(LaNdY)_(0.12)O_(2)mixed oxides was realized via a facile and scalable approach,namely,sulfateaided coprecipitation method was labelled as CZ-S.Sulfate ion(SO_(4)^(2-))was added into raw solution in the form of sulfuric acid and acted as coordination agent.The control sample was prepared by conventional coprecipitation method without sulfuric acid added and labelled as CZ.The promotion effect of sulfate ion was analyzed systematically by X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),N_(2)adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),OSC and hydrogen temperatureprogrammed reduction(H_(2)-TPR)analysis.XRD and high resolution TEM results reveal that CZ-S have homogeneous distributions of elements.TEM and SEM images show that fresh samples of CZ-S have narrower distributions of grain sizes and larger pore sizes than those of CZ.Through cross analysis of structure and morphology of CZ and CZ-S,we find that the introduction of sulfate ions results in uniform distributions of elements,narrows distributions of grain sizes,and enables the formation of secondary loose packing of sub-particles,which lead to enhanced thermal stability of the samples of CZ-S upon aging process at high temperature.After aging treatment at 1100℃for 10 h,aged samples of CZ-S present larger specific surface areas and pore volumes than the aged sample prepared by conventional coprecipitation method without sulfate ions added.Furthermore,the aged sample of CZ-S2(SO_(4)^(2-)/Zr=1)possesses the highest specific surface area of 21.9 m2/g and the biggest pore volume of 0.035 mL/g among all aged samples.展开更多
As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray ...As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize their microstructures. All the La-TM oxides were made up of single phases. Electrochemical measurements showed that the maximum discharge capacities of LaTiO(3), LaVO(4), LaCrO(3), and LaMnO(3) electrodes at 303 K were 367, 187, 318, and 278 mAh/g, respectively. X-ray photoelectron spectroscopy (XPS) and XRD Rietveld analysis were carried out to discuss the electrochemical reaction mechanism. Electrode kinetics was studied by electrochemical impedance spectrum (EIS). The results showed that the maximum discharge capacity was directly related to the charge-transfer resistance (R(ct)) of La-TM oxide electrode. The cyclic properties of the four oxides should be further improved and the discharge capacity of LaMnO(3) (about 96 mAh/g) was the highest after 10(th) charge/discharge cycles.展开更多
Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results revea...Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.展开更多
文摘The Ti base PbO 2 electrode prepared by electrodeposition of PbO 2 on the surface of titanium was used for electro catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition of PbO 2 at a higher current density for a short time, then followed by a lower current density can get a compact and combinative PbO 2 layer. The properties of a Ti/PbO 2 electrode with an interlayer of oxide are the best. When this kind of electrode is used to treat phenol containing waste water, the phenol removal rate is higher and the slot voltage is lower. In addition, by using the phenol removal rate as an index, the influences of electrolysis current density, mass transfer condition and pH were studied and the optimal condition was confirmed.
基金supported by the National Natural Science Foundation of China(U1960107)the Natural Science Foundation of Hebei Province(E2022501014)+3 种基金the “333”Talent Project of Hebei Province(A202005018)the Fundamental Research Funds for the Central Universities(N2123034)the Science and Technology Research Youth Fund Project of Higher Education Institutions of Hebei Province(QN2022196)the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.
基金Supported by National Natural Science Foundation of China(Grant Nos.51335005,51321092)National Key Basic Research Program of China(973 Program,Grant No.2013CB934200)the Foundation for the Supervisor of Beijing Excellent Doctoral Dissertation(Grant No.20111000305)
文摘The performance of a lubricant largely depends on the additives it involves. However, currently used additives cause severe pollution if they are burned and exhausted. Therefore, it is necessary to develop a new generation of green additives. Graphene oxide（GO） consists of only C, H and O and thus is considered to be environmentally friendly. So the tribological properties of the few-layer GO sheet as an additive in hydrocarbon base oil are investigated systematically. It is found that, with the addition of GO sheets, both the coefficient of friction（COF） and wear are decreased and the working temperature range of the lubricant is expanded in the positive direction. Moreover, GO sheets has better performance under higher sliding speed and the optimized concentration of GO sheets is determined to be 0.5wt%. After rubbing, GO is detected on the wear scars through Raman spectroscopy. And it is believed that, during the rubbing, GO sheets adhere to the sliding surfaces, behaving like protective films and preventing the sliding surfaces from contacting with each other directly. This paper proves that the GO sheet is an effective lubricant additive, illuminates the lubrication mechanism, and provides some critical parameters for the practical application of GO sheets in lubrication.
文摘Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distributed ranges of the superconductive transition temperature (Tc) for complex oxides, and Tc values for cuprate superconductors. The calculated results indicated that the adjusted ANN can be used to predict superconductive properties for unknown oxides.
基金Supported by the Iraqi Ministry of Higher Education and Scientific Research and University of Baghdad
文摘We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB723402 and 2014CB648300the National Natural Science Foundation of China under Grant Nos 61204095 and 61475074+3 种基金the National Science Fund for Excellent Young Scholars under Grant No 21322402the Natural Science Foundation of Jiangsu Province under Grant No BK2012431,the Natural Science Foundation of the Education Committee of Jiangsu Province under Grant No 14KJB510027the Ministry of Education of China under Grant No IRT1148the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We investigate the memory properties of the ITO/graphene oxide/Al diodes. It is found that the devices show different memory behaviors with the diverse geometry and thickness of Al. When the thickness of the Al electrode is relatively thick, the device of the cross-point Al electrode shows a three-level memory effect, and the counterpart device of the cross-bar Al electrode exhibits a volatile static random access memory effect. When the thickness of the AI electrode is thinner, the above devices demonstrate a flash memory effect. The different memory behaviors of ITO/GO/AI diodes are ascribed to the mode and degree of reduction and oxidation of GO.
基金This work was financially supported by the High‐level Talents'Discipline Construction Fund of Shandong University(31370089963078)the Shandong Provincial Science and Technology Major Project(2018JM RH0211 and 2017CXGC1010)+3 种基金the Research Funds of Shandong University(10000089395121)the Natural Science Foundation of Shandong Province(ZR2019MEM052 and ZR2017MEM002)The National Natural Science Foundation of China(grant no.52002287)the Start‐up Funding of Wenzhou University are acknowledged.
文摘Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.
基金the financial support from the National Natural Science Foundation of China–Academy of Engineering Physics(No.10976014)Natural Science Foundation of Jiangsu Province(No.BK2011697)
文摘A silica gel supported cobalt（lI） Schiff base complex was synthesized and used for the oxidation of alkyl aromatics using molecular oxygen as an oxidant under atmosphere pressure. The catalyst shows a high conversion of alkyl aromatics and selectivity to benzylic ketones, and could be reused at least 5 times without significant loss of catalytic activity.
文摘We demonstrate a femtosecond mode-locked erbium-doped fiber laser（EDFL） using a nickel oxide（Ni O） as a saturable absorber（SA）. Ni O nanoparticles are hosted into polyethylene oxide film and attached to fiber ferrule in the laser cavity. The Ni O-SA shows a 39% modulation depth with a 0.04 MW∕cm^2 saturation intensity. Our ring laser cavity based on erbium-doped active fiber with managed intracavity dispersion has the ability to generate ultrashort pulses with a full width at half-maximum（FWHM） of around 2.85 nm centered at 1561.8 nm.The pulses repeat at a frequency of 0.96 MHz and duration of 950 fs.
基金financial support from the Guangdong Innovative Research Team Program of China (201101C0105067115)DSTA Singapore (Project DSTA-NUS-DIRP/9010100347)National Research Foundation Singapore (R398-001-062-281)
文摘We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets display highly efficient broadband optical limiting activities for femtosecond laser pulses at 400,800,and 1400 nm with very low limiting thresholds.Femtosecond pump–probe measurement results revealed that nonlinear absorption played an important role for the observed optical limiting activities.High flexibility and efficient optical limiting activities of these materials allow these composite sheets to be attached to nonplanar optical sensors in order to protect them from light-induced damage.
基金supported by the National Natural Science Foundation of China(Nos.61575168 and 61265009)the Xinjiang Science and Technology Project(No.201412112)
文摘The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- filtrated into a PSi device. The results indicate that the intensity of the fluorescence of the GOQD-inflltrated multilayer with a high reflection band located at its fluorescence spectra scope is approximately double that of the single layer sample. This indicates that the multilayer GOQD-infiltrated PSi substrate is a suitable material for the preparation of sensitive photoluminescence biosensors.
基金Project supported by Beijing Nova Program(Z181100006218030)。
文摘Ceria-zirconia based mixed oxides(CZs)have been applied in three-way catalysts(TWCs)for their high surface area and oxygen storage capacity(OSC).In this work,enhanced thermal stability of Ce_(0.33)Zr_(0.55)(LaNdY)_(0.12)O_(2)mixed oxides was realized via a facile and scalable approach,namely,sulfateaided coprecipitation method was labelled as CZ-S.Sulfate ion(SO_(4)^(2-))was added into raw solution in the form of sulfuric acid and acted as coordination agent.The control sample was prepared by conventional coprecipitation method without sulfuric acid added and labelled as CZ.The promotion effect of sulfate ion was analyzed systematically by X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),N_(2)adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),OSC and hydrogen temperatureprogrammed reduction(H_(2)-TPR)analysis.XRD and high resolution TEM results reveal that CZ-S have homogeneous distributions of elements.TEM and SEM images show that fresh samples of CZ-S have narrower distributions of grain sizes and larger pore sizes than those of CZ.Through cross analysis of structure and morphology of CZ and CZ-S,we find that the introduction of sulfate ions results in uniform distributions of elements,narrows distributions of grain sizes,and enables the formation of secondary loose packing of sub-particles,which lead to enhanced thermal stability of the samples of CZ-S upon aging process at high temperature.After aging treatment at 1100℃for 10 h,aged samples of CZ-S present larger specific surface areas and pore volumes than the aged sample prepared by conventional coprecipitation method without sulfate ions added.Furthermore,the aged sample of CZ-S2(SO_(4)^(2-)/Zr=1)possesses the highest specific surface area of 21.9 m2/g and the biggest pore volume of 0.035 mL/g among all aged samples.
基金Project supported by the National Natural Science Foundation of China (50971096)
文摘As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize their microstructures. All the La-TM oxides were made up of single phases. Electrochemical measurements showed that the maximum discharge capacities of LaTiO(3), LaVO(4), LaCrO(3), and LaMnO(3) electrodes at 303 K were 367, 187, 318, and 278 mAh/g, respectively. X-ray photoelectron spectroscopy (XPS) and XRD Rietveld analysis were carried out to discuss the electrochemical reaction mechanism. Electrode kinetics was studied by electrochemical impedance spectrum (EIS). The results showed that the maximum discharge capacity was directly related to the charge-transfer resistance (R(ct)) of La-TM oxide electrode. The cyclic properties of the four oxides should be further improved and the discharge capacity of LaMnO(3) (about 96 mAh/g) was the highest after 10(th) charge/discharge cycles.
基金Project supported by National Basic Research Program of China(2010CB732300)111 Project(B08021)China Scholarship Council for the Joint-Training Scholarship Program with Institut de Recherches sur la Catalyse et l'Environnement de Lyon(IRCELYON)and Universite Claude Bernard Lyon 1(UCBL1)
文摘Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.
