Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)...Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)perovskite oxide.The obtained porous layered LSCF has a large specific surface area of 23.74 m^(2)/g,four times higher than that prepared by the traditional sol-gel method(5.08 m^(2)/g).The oxygen reduction reaction activity of the oxide in 0.1 mol/L KOH solution was studied using a rotating ring-disk electrode.In the tests,the initial potential of 0.88 V(vs.reversible hydrogen electrode)and the limiting diffusion current density of 5.02 mA/cm^(2)were obtained at 1600 r/min.Therefore,higher catalytic activity and stability were demonstrated,compared with the preparation of LSCF perovskite oxide by the traditional method.展开更多
The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse ref...The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse reflectance spectroscopy （UV-vis DRS） and Brunauer-Emmett-Teller adsorption method. Compared to pure BiOCl or BiOBr, the BiOClxBr1–x solid solution has enhanced photocatalytic degradation activity for rhodamine B. This phenomenon can be explained to the hierarchical structure, lager specific surface area and appropriate energy gap of the obtained BiOClxBr1–x solid solution. The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.展开更多
The photocatalytic degradation of norfloxacin by bismuth tungstate(Bi2WO6)with different hierarchical architectures wasinvestigated under visible light irradiation.Bi2WO6was prepared by hydrothermal method with the re...The photocatalytic degradation of norfloxacin by bismuth tungstate(Bi2WO6)with different hierarchical architectures wasinvestigated under visible light irradiation.Bi2WO6was prepared by hydrothermal method with the reaction solution pH rangingfrom4to11.The relatively ultrathin Bi2WO6nanoflakes prepared at pH4showed excellent adsorption and photodegradationefficiency towards norfloxacin.The characterization results showed that Bi2WO6prepared at pH4had a larger specific area andfaster photo-generated carrier separation rate.The decay rate reached the maximum in weak alkaline reaction solution,which couldbe attributed to the presence of moderate OH-anions.The present study demonstrated that the smaller size of Bi2WO6could be anefficient photocatalyst on the degradation of norfloxacin in the aquatic environment.展开更多
HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion ...HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n- dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.展开更多
Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for t...Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.展开更多
The oxygen reduction reaction （ORR） in the cathode catalyst layer （CCL） of polymer electrolyte fuel cells （PEFC） is one of the major causes of performance loss during operation. In addition, the CCL is the most ...The oxygen reduction reaction （ORR） in the cathode catalyst layer （CCL） of polymer electrolyte fuel cells （PEFC） is one of the major causes of performance loss during operation. In addition, the CCL is the most expensive component due to the use of a Pt catalyst. Apart from the ORR itself, the species transport to and from the reactive sites determines the performance of the PEFC. The effective transport properties of the species in the CCL depend on its nanostructure. Therefore a three-dimensional reconstruction of the CCL is required. A series of two-dimensional images was obtained from focused ion beam- scanning electron microscope （FIB-SEM） imaging and a segmentation method for the two-dimensional images has been developed. The pore size distribution （PSD） was calculated for the three-dimensional geometry. The influence of the alignment and the anisotropic pixel size on the PSD has been investigated. Pores were found in the range between 5 nm and 205 nm. Evaluation of the Knudsen number showed that gas transport in the CCL is governed by the transition flow regime. The liquid water transport can be described within continuum hydrodynamics by including suitable slip flow boundary conditions.展开更多
In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similari...In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similarities, including(1) initial formation of metal alkoxides precursors and(2) subsequent structural evolution of products from tiered plates to jigsaw puzzles; then to extrusion ridges, nests and spindles; and thereafter to final mazelike structures driven by persistent thermal decomposition of preformed precursors. Based on their unique surface morphologies in sinuous asymmetry, it is anticipated that such mazelike hierarchical structures may shed new light on the development of morphology-controlled adsorption and heterogeneous catalysts.展开更多
基金Project(20192BAB216015)supported by the Science and Technology Program of Jiangxi Province,ChinaProjects(GJJ180464,GJJ171499)supported by the Science and Technology Program of Education Department of Jiangxi Province,China+2 种基金Project(jxxjbs17057)supported by the Scientific Research Foundation of Jiangxi University of Science and Technology,ChinaProject([2018]50)supported by the Key R&D Programs of Science and Technology Project of Ganzhou City,ChinaProject([2017]179)supported by the Science and Technology Project of Ganzhou City,China。
文摘Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)perovskite oxide.The obtained porous layered LSCF has a large specific surface area of 23.74 m^(2)/g,four times higher than that prepared by the traditional sol-gel method(5.08 m^(2)/g).The oxygen reduction reaction activity of the oxide in 0.1 mol/L KOH solution was studied using a rotating ring-disk electrode.In the tests,the initial potential of 0.88 V(vs.reversible hydrogen electrode)and the limiting diffusion current density of 5.02 mA/cm^(2)were obtained at 1600 r/min.Therefore,higher catalytic activity and stability were demonstrated,compared with the preparation of LSCF perovskite oxide by the traditional method.
基金Project(2016TP1007)supported by the Hunan Provincial Science and Technology Plan Project,China
文摘The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse reflectance spectroscopy （UV-vis DRS） and Brunauer-Emmett-Teller adsorption method. Compared to pure BiOCl or BiOBr, the BiOClxBr1–x solid solution has enhanced photocatalytic degradation activity for rhodamine B. This phenomenon can be explained to the hierarchical structure, lager specific surface area and appropriate energy gap of the obtained BiOClxBr1–x solid solution. The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.
基金Projects(51579096,51222805,51521006,51508175) supported by the National Natural Science Foundation of ChinaProject supported by the National Program for Support of Top-Notch Young Professionals of China+1 种基金Project(NCET–11–0129) supported by the Program for New Century Excellent Talents in University from the Ministry of Education of ChinaProject(CX2015B095) supported by the Hunan Province Innovation Foundation for Postgraduate,China
文摘The photocatalytic degradation of norfloxacin by bismuth tungstate(Bi2WO6)with different hierarchical architectures wasinvestigated under visible light irradiation.Bi2WO6was prepared by hydrothermal method with the reaction solution pH rangingfrom4to11.The relatively ultrathin Bi2WO6nanoflakes prepared at pH4showed excellent adsorption and photodegradationefficiency towards norfloxacin.The characterization results showed that Bi2WO6prepared at pH4had a larger specific area andfaster photo-generated carrier separation rate.The decay rate reached the maximum in weak alkaline reaction solution,which couldbe attributed to the presence of moderate OH-anions.The present study demonstrated that the smaller size of Bi2WO6could be anefficient photocatalyst on the degradation of norfloxacin in the aquatic environment.
基金Supported by the National Natural Science Foundation of China(91116001)
文摘HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n- dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.
文摘Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.
文摘The oxygen reduction reaction （ORR） in the cathode catalyst layer （CCL） of polymer electrolyte fuel cells （PEFC） is one of the major causes of performance loss during operation. In addition, the CCL is the most expensive component due to the use of a Pt catalyst. Apart from the ORR itself, the species transport to and from the reactive sites determines the performance of the PEFC. The effective transport properties of the species in the CCL depend on its nanostructure. Therefore a three-dimensional reconstruction of the CCL is required. A series of two-dimensional images was obtained from focused ion beam- scanning electron microscope （FIB-SEM） imaging and a segmentation method for the two-dimensional images has been developed. The pore size distribution （PSD） was calculated for the three-dimensional geometry. The influence of the alignment and the anisotropic pixel size on the PSD has been investigated. Pores were found in the range between 5 nm and 205 nm. Evaluation of the Knudsen number showed that gas transport in the CCL is governed by the transition flow regime. The liquid water transport can be described within continuum hydrodynamics by including suitable slip flow boundary conditions.
基金supported by the National Natural Science Foundation of China(51072087)Specialized Research Fund for the Doctoral Program of Higher Education(20113719110001)
文摘In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similarities, including(1) initial formation of metal alkoxides precursors and(2) subsequent structural evolution of products from tiered plates to jigsaw puzzles; then to extrusion ridges, nests and spindles; and thereafter to final mazelike structures driven by persistent thermal decomposition of preformed precursors. Based on their unique surface morphologies in sinuous asymmetry, it is anticipated that such mazelike hierarchical structures may shed new light on the development of morphology-controlled adsorption and heterogeneous catalysts.
