Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Rama...Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Raman spectroscopy. The results showed that all the samples held the structure of MCM-48, and Ce could enter the framework of MCM-48. However, when Ce/Si molar ratio in the sampies was high （0.04 or 0.059）, there were CeO2 crystallites as secondary phase in the extraframework of MCM-48. Ce-doped MCM-48 was a very efficient catalyst for the oxidation of cyclohexane in a solvent-free system with oxygen as an oxidant. In the conditions of 0.5 MPa 02 and 413 K for 5 h, the conversion of cyclohexane was 8.1% over Ce-MCM-48-0.02, the total selectivity of cyclohexanol and cyclohaxnone was 98.7%. With an increase of Ce content, the conversion of cyclohexane and the selectivity to cyclohexanol decreased somewhat, but the selectivity to cyclohexanone increased.展开更多
MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based o...MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.展开更多
Smartcombination of manifold carbonaceous materials with admirable functionalities(like full of pores/functional groups,high specific surface area) is still a mainstream/preferential way to address knotty issues of po...Smartcombination of manifold carbonaceous materials with admirable functionalities(like full of pores/functional groups,high specific surface area) is still a mainstream/preferential way to address knotty issues of polysulfides dissolution/shuttling and poor electrical conductivity for S-based cathodes.However,extensive use of conductive carbon fillers in cell designs/technology would induce electrolytic overconsumption and thereby shelve high-energy-density promise of Li-S cells.To cut down carbon usage,we propose the incorporation of multi-functionalized NiFe2O4 quantum dots(QDs) as affordable additive substitutes.The total carbon content can be greatly curtailed from 26%(in traditional S/C cathodes) to a low/commercial mass ratio(~5%).Particularly,note that NiFe2O4 QDs additives own superb chemisorption interactions with soluble Li2Sn molecules and proper catalytic features facilitating polysulfide phase conversions and can also strengthen charge-transfer capability/redox kinetics of overall cathode systems.Benefiting from these intrinsic properties,such hybrid cathodes demonstrate prominent rate behaviors(decent capacity retention with ~526 mAh g^-1 even at 5 A g^-1) and stable cyclic performance in LiNO3-free electrolytes(only ~0.08% capacity decay per cycle in 500 cycles at 0.2 A g^-1).This work may arouse tremendous research interest in seeking other alternative QDs and offer an economical/more applicable methodology to construct low-carbon-content electrodes for practical usage.展开更多
Performance degradation shortens the life of solid oxide fuel cells in practical applications.Revealing the degradation mechanism is crucial for the continuous improvement of cell durability.In this work,the effects o...Performance degradation shortens the life of solid oxide fuel cells in practical applications.Revealing the degradation mechanism is crucial for the continuous improvement of cell durability.In this work,the effects of cell operating conditions on the terminal voltage and anode microstructure of a Ni-yttria-stabilized zirconia anode-supported single cell were investigated.The microstructure of the anode active area near the electrolyte was characterized by laser optical microscopy and focused ion beam-scanning electron microscopy.Ni depletion at the anode/electrolyte interface region was observed after 100 h discharge tests.In addition,the long-term stability of the single cell was evaluated at 700℃for 3000 h.After an initial decline,the anode-supported single cell exhibits good durability with a voltage decay rate of 0.72%/kh and an electrode polarization resistance decay rate of 0.17%/kh.The main performance loss of the cell originates from the initial degradation.展开更多
Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fue...Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction.This review focuses on the methanol tolerant noble metal-based electrocatalysts,including platinum and palladium-based alloys,noble metal–carbon based composites,transition metal-based catalysts,carbon-based metal catalysts,and metal-free catalysts.The understanding of the correlation between the activity and the synthesis method,electrolyte environment and stability issues are highlighted.For the transition metal-based catalyst,their activity,stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed.Finally,strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented.This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.展开更多
During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turb...During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turbine blade castings at the still air cooling and forced air cooling stages during heat treatment process. The method was used to measure the distortion behavior at the cooling stages in both normalizing and tempering processes. At the normalization, the distortion at the blade comer near outlet side undergoes four stages with alternating bending along positive and negative directions. At the tempering stage, the distortion could be divided into two steps. The temperature difference between the two surfaces of blade casting was employed to analyze the distortion mechanism. The measured results could be applied to guide the production, and the machining allowance could be reduced by controlling the distortion behavior.展开更多
A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied. This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for flu...A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied. This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.展开更多
Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density an...Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.展开更多
For a long time,in aqueous zinc-ion batteries,the intercalation/extraction chemistry of Zn2+/H+has been considered as the primary energy storage mechanism in vanadium-based compounds.Herein,we observed an interesting ...For a long time,in aqueous zinc-ion batteries,the intercalation/extraction chemistry of Zn2+/H+has been considered as the primary energy storage mechanism in vanadium-based compounds.Herein,we observed an interesting phase transition of V_(2)O_(3) to V_(2)O_(5)·3H_(2)O under high-voltage conditions.The reconstructed phase(V_(2)O_(5)·3H_(2)O)displays an improved specific capacity of 472.4 mA h g^(-1),about 5 times larger than that of the original compound(V_(2)O_(3)).What’s more,the electrode exhibits a highly reversible conversion reaction between V_(2)O_(5)·3H_(2)O and Zn_(3)V_(2)O_(7)(OH)_(2)·2H_(2)O(ZVO)during the charge/discharge process,showing an excellent rate capability and cycling stability.The findings also confirm the electrochemical activity of ZVO,which has generally been considered to be an inactive by-product.This energy storage mechanism,different from the previously reported intercalation chemistry,offers a new insight to understand the electrochemical behavior of V-based electrode materials.展开更多
The construction of highly conductive structures with excellent adsorption–catalytic properties to accelerate electron transfer and suppress polysulfide shuttle is considered as an effective strategy to achieve well-...The construction of highly conductive structures with excellent adsorption–catalytic properties to accelerate electron transfer and suppress polysulfide shuttle is considered as an effective strategy to achieve well-performing sodium–sulfur batteries.Herein,a self-supported tessellated N-doped carbon/CoSe_(2)(NCCS)is developed as a sulfur host for sodium–sulfur batteries by a simple deposition–selenization of lyophilized bacterial cellulose(BC),where NC acts as a conductive network to ensure the rapid initiation of efficient catalytic reactions at the tessellated CoSe_(2)interface and maintain good structural stability.展开更多
High energy density room temperature sodium–sulfur(RT Na–S)batteries are receiving increasing attention as promising energy storage systems.However,the volume expansion of sulfur and the shuttle effect of polysulfid...High energy density room temperature sodium–sulfur(RT Na–S)batteries are receiving increasing attention as promising energy storage systems.However,the volume expansion of sulfur and the shuttle effect of polysulfides are the biggest obstacles to their development.In this study,a 3D porous aerogel(hybridized by Ti_(3)C_(2)T_(x)MXene and rGO)adhered with cobalt nanoparticles(MG-Co)is applied to RT Na–S batteries.展开更多
Prussian blue analogues(PBAs)as a kind of promising cathode material for sodium-ion batteries(SIBs)have attracted much attention due to their low price and open three-dimensional(3D)channel structure.Here,a facile wet...Prussian blue analogues(PBAs)as a kind of promising cathode material for sodium-ion batteries(SIBs)have attracted much attention due to their low price and open three-dimensional(3D)channel structure.Here,a facile wet-chemical method is used to synthesize a nano-sized NiFe-PBA compound.The as-syn thesized NiFe-PBA not only exhibits good structural stability but also demonstrates impressive electro chemical performance when it is used as a cathode in SIBs.Both liquid-state and solid-state sodium-ion batteries(SSIBs)demonstrate excellent cycling stability with a capacity retention of 85.8%and 86.7%,respectively,after 1120 cycles.展开更多
La/Ce_(0.5)Mn_(0.5) catalysts prepared by wetness impregnation of Ce_(_(0.5))Mn_(_(0.5)) with La(NO_(3))_(3)(aq) were used in catalytic oxidation of ethyl acetate.Characterization by X-ray diffractometer(XRD),H2 tempe...La/Ce_(0.5)Mn_(0.5) catalysts prepared by wetness impregnation of Ce_(_(0.5))Mn_(_(0.5)) with La(NO_(3))_(3)(aq) were used in catalytic oxidation of ethyl acetate.Characterization by X-ray diffractometer(XRD),H2 temperature programmed reduction(H2-TPR),X-ray photoelectron spectroscopy(XPS) and Raman shows that La/Ce_(0.5)Mn_(0.5) catalysts have fluorite-like structure.LalCe_(0.5)Mn_(0.5) catalyst presents high activity with T90(the temperature needed for 90% conversion) of 200℃,where ethyl acetate is almost completely converted into CO_(2).The conversion at 195℃ maintains at 80% for at least 100 h.The intermediates were mainly ethanol and acetaldehyde whose amounts are below250 × 10^(-6) and 16 × 10^(-6),respectively.In situ FTIR indicates that the modes of dissociative adsorption of ethyl acetate are related to surface oxygen species,which affect the stability of catalysts and the selectivity for ethanol and acetaldehyde intermediates.展开更多
Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient...Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient temperature.The textural and surface properties of the activated carbons were characterized by nitrogen adsorption,temperature-programmed desorption（TPD）and Boehm titration.The activated carbon support with meso-and macropores,and oxygen-functional groups performs higher CS2 removal ability at ambient temperature.The effects of flow rate,CS2 inlet concentration,temperature and relative humidity on CS2 removal were also investigated.High efficient removal is obtained at temperature of 50-C,space velocity of 2000 h-1,inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20%with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.展开更多
Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHT...Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHTC） between the surface of slab casting and inner mold. Calculated temperature dependent values of IHTC were obtained from a numerical solution. The calculated temperatures agreed well with the measurement of cooling profile.展开更多
The interaction of DNA with cationic gemini suffactant trimethylene-1,3-bis （dodecyl dimethyl-ammonium bromide） （12-3-12） and anionic surfactant sodium dodecyl sulfate （SDS） mixed system has been investigated by...The interaction of DNA with cationic gemini suffactant trimethylene-1,3-bis （dodecyl dimethyl-ammonium bromide） （12-3-12） and anionic surfactant sodium dodecyl sulfate （SDS） mixed system has been investigated by measuring the fluorescence, zeta potential, UV-Vis spectrum, and circular dichroism. In the absence of SDS, owing to the electrostatic and hydrophobic interactions, 12-3-12 forms micelle-like structure on the DNA chain before the micellization in bulk phase. For the mixed system of 12-3-12 and SDS, the negative charges on SDS can compete against DNA to bind with cationic 12-3-12 because of the stronger interaction between oppositely charged surfactants, and thus, the catanionic mixed micelles are formed before the formation of DNA/12-3-12 complexes. There-after, the positive charges on the mixed micelles bind with DNA, and thus, the change of the zeta potential from negative to positive is distinctly different from the system without SDS. Meanwhile, the existence of SDS postpones the exclusion of ethidium bromide （EB） from DNA/EB complexes. The conformation of DNA undergoes a change from native B-form to chiral ψ-phase as binding with 12-3-12 process. Upon adding SDS to the DNA/12-3-12 complex solution, however, DNA is released to the bulk and the ψ-phase returns to B-form again.展开更多
The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence ...The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence of water on Pd/CeO2-C;but a decrease is found on Pd/CeO2-R.Catalyst characterization reveals that Pd is mainly in the form of solid solution(PdxCe1-xO2-σ)on Pd/CeO2-R and a mixture of metal and PdxCe1-xO2-σsolid solution on Pd/CeO2-C.The strong interaction between Pd and CeO2-R results in the form of stable bidentate carbonates species;while the relatively weak interaction between Pd and CeO2-C leads to the produce of unstable monodentate carbonates species.The effects of water on CO oxidation activity closely relate with the Pd chemical state and the types of carbonates species.Water restrains CO adsorption on PdxCe1-xO2-σsolid solution,but it has negligent effects on metallic Pd species.In the presence of water,bidentate carbonates species remains stable but the decrease in the amount of monodentate carbonates species is observed.展开更多
Microstructures and precipitation behaviours of Mg94Y4Zn2 （at. %） extruded alloy during solution treatment and ageing processes were investigated. Three major phases were observed in the as-cast Ug94Zn2Y4 alloy：α-...Microstructures and precipitation behaviours of Mg94Y4Zn2 （at. %） extruded alloy during solution treatment and ageing processes were investigated. Three major phases were observed in the as-cast Ug94Zn2Y4 alloy：α-Mg, block shaped 1 8R long period stacking ordered （LPSO） phase and Mg24Y5 cuboid particles. After homogenization and extrusion, the block shaped LPSO phase changed into plate-like shape aligned along the direction of extrusion. During solution treatment, a small fraction of LPSO phase was transformed from 18R structure to 14H type. The nano-scale β＇ phase with its close-packed planes being perpendicular to the direction of both α-Mg and LPSO structure was precipitated at ageing stage. The coexistence of β＇ and LPSO phase contributes to the strengthening of the alloy, with microhardness for the matrix and LPSO structures reaching 145.8 and 155,0 HV, respectively.展开更多
Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 V of DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction ...Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 V of DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction or partly turned into solution, while for the gels. with higher polyacrylamide concentration, a complete gel-sol transition was observed in a short time.展开更多
基金the National Basic Research Program of China (2004CB719500)the Commission of Science and Technology of Shanghai Municipality (06DJ14006)Shanghai Municipal Education Commission (2008CG35)
文摘Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Raman spectroscopy. The results showed that all the samples held the structure of MCM-48, and Ce could enter the framework of MCM-48. However, when Ce/Si molar ratio in the sampies was high （0.04 or 0.059）, there were CeO2 crystallites as secondary phase in the extraframework of MCM-48. Ce-doped MCM-48 was a very efficient catalyst for the oxidation of cyclohexane in a solvent-free system with oxygen as an oxidant. In the conditions of 0.5 MPa 02 and 413 K for 5 h, the conversion of cyclohexane was 8.1% over Ce-MCM-48-0.02, the total selectivity of cyclohexanol and cyclohaxnone was 98.7%. With an increase of Ce content, the conversion of cyclohexane and the selectivity to cyclohexanol decreased somewhat, but the selectivity to cyclohexanone increased.
基金financially supported by the National Natural Science Foundation of China(No.52002354)China Postdoctoral Science Foundation(No.2020M672256)。
文摘MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.
基金financial supports from National Natural Science Foundation of China (51802269 and 21773138)Chongqing Natural Science Foundation (cstc2018jcyjAX0624)+1 种基金Fundamental Research Funds for the Central Universities (XDJK2019AA002)Venture & Innovation Support Program for Chongqing overseas returnees (cx2018027)。
文摘Smartcombination of manifold carbonaceous materials with admirable functionalities(like full of pores/functional groups,high specific surface area) is still a mainstream/preferential way to address knotty issues of polysulfides dissolution/shuttling and poor electrical conductivity for S-based cathodes.However,extensive use of conductive carbon fillers in cell designs/technology would induce electrolytic overconsumption and thereby shelve high-energy-density promise of Li-S cells.To cut down carbon usage,we propose the incorporation of multi-functionalized NiFe2O4 quantum dots(QDs) as affordable additive substitutes.The total carbon content can be greatly curtailed from 26%(in traditional S/C cathodes) to a low/commercial mass ratio(~5%).Particularly,note that NiFe2O4 QDs additives own superb chemisorption interactions with soluble Li2Sn molecules and proper catalytic features facilitating polysulfide phase conversions and can also strengthen charge-transfer capability/redox kinetics of overall cathode systems.Benefiting from these intrinsic properties,such hybrid cathodes demonstrate prominent rate behaviors(decent capacity retention with ~526 mAh g^-1 even at 5 A g^-1) and stable cyclic performance in LiNO3-free electrolytes(only ~0.08% capacity decay per cycle in 500 cycles at 0.2 A g^-1).This work may arouse tremendous research interest in seeking other alternative QDs and offer an economical/more applicable methodology to construct low-carbon-content electrodes for practical usage.
基金supported by the National Key R&D Program of China(No.2018YFB1502202)the Fundamental Research Funds for the Central Universities(No.FRF-GF-20-09B).
文摘Performance degradation shortens the life of solid oxide fuel cells in practical applications.Revealing the degradation mechanism is crucial for the continuous improvement of cell durability.In this work,the effects of cell operating conditions on the terminal voltage and anode microstructure of a Ni-yttria-stabilized zirconia anode-supported single cell were investigated.The microstructure of the anode active area near the electrolyte was characterized by laser optical microscopy and focused ion beam-scanning electron microscopy.Ni depletion at the anode/electrolyte interface region was observed after 100 h discharge tests.In addition,the long-term stability of the single cell was evaluated at 700℃for 3000 h.After an initial decline,the anode-supported single cell exhibits good durability with a voltage decay rate of 0.72%/kh and an electrode polarization resistance decay rate of 0.17%/kh.The main performance loss of the cell originates from the initial degradation.
基金supported by the National Natural Science Foundations of China(22150410340)the Chongqing Science&Technology Commission(catc2018jcyjax0582)。
文摘Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction.This review focuses on the methanol tolerant noble metal-based electrocatalysts,including platinum and palladium-based alloys,noble metal–carbon based composites,transition metal-based catalysts,carbon-based metal catalysts,and metal-free catalysts.The understanding of the correlation between the activity and the synthesis method,electrolyte environment and stability issues are highlighted.For the transition metal-based catalyst,their activity,stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed.Finally,strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented.This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.
基金supported financially by the National Eleventh Five-Year Science and Technology Support Program of China through Grant No.2007BAF02B02Major National Sci-Tech Project of China No 2011ZX04014-052
文摘During heat treatment process, the distortion behavior inevitably appears in hydraulic turbine blade castings. In this research, a technology was developed for real-time measurement of the distortion in hydraulic turbine blade castings at the still air cooling and forced air cooling stages during heat treatment process. The method was used to measure the distortion behavior at the cooling stages in both normalizing and tempering processes. At the normalization, the distortion at the blade comer near outlet side undergoes four stages with alternating bending along positive and negative directions. At the tempering stage, the distortion could be divided into two steps. The temperature difference between the two surfaces of blade casting was employed to analyze the distortion mechanism. The measured results could be applied to guide the production, and the machining allowance could be reduced by controlling the distortion behavior.
基金supported by National Basic Research 973 Program (No.2006CB806200) and Scientific Committee of Shanghai.
文摘A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied. This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.
基金financially supported by the National Natural Science Foundation of China(52074023)the Beijing Natural Science Foundation(2222062)+1 种基金the National Key R&D Program of China(2018YFB0905600)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-21-023)。
文摘Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.
基金support from the National Natural Science Foundation of China(No.22179109,22005251)the Innovation Platform for Academinicians of Hainan Province.
文摘For a long time,in aqueous zinc-ion batteries,the intercalation/extraction chemistry of Zn2+/H+has been considered as the primary energy storage mechanism in vanadium-based compounds.Herein,we observed an interesting phase transition of V_(2)O_(3) to V_(2)O_(5)·3H_(2)O under high-voltage conditions.The reconstructed phase(V_(2)O_(5)·3H_(2)O)displays an improved specific capacity of 472.4 mA h g^(-1),about 5 times larger than that of the original compound(V_(2)O_(3)).What’s more,the electrode exhibits a highly reversible conversion reaction between V_(2)O_(5)·3H_(2)O and Zn_(3)V_(2)O_(7)(OH)_(2)·2H_(2)O(ZVO)during the charge/discharge process,showing an excellent rate capability and cycling stability.The findings also confirm the electrochemical activity of ZVO,which has generally been considered to be an inactive by-product.This energy storage mechanism,different from the previously reported intercalation chemistry,offers a new insight to understand the electrochemical behavior of V-based electrode materials.
基金the National Natural Science Foundation of China(No.22005251,No.21773188,and No.21972111)the Chongqing Natural Science Foundation(cstc2021ycjh-bgzxm0164)the Central Universities Fundamental Research Funds(XDJK2019AA002).
文摘The construction of highly conductive structures with excellent adsorption–catalytic properties to accelerate electron transfer and suppress polysulfide shuttle is considered as an effective strategy to achieve well-performing sodium–sulfur batteries.Herein,a self-supported tessellated N-doped carbon/CoSe_(2)(NCCS)is developed as a sulfur host for sodium–sulfur batteries by a simple deposition–selenization of lyophilized bacterial cellulose(BC),where NC acts as a conductive network to ensure the rapid initiation of efficient catalytic reactions at the tessellated CoSe_(2)interface and maintain good structural stability.
基金support from the National Natural Science Foundation of China(no.21773188,no.21972111)Fundamental Research Funds for the Central Universities(XDJK2019AA002)Postgraduate tutor team building project(XYDS201911).
文摘High energy density room temperature sodium–sulfur(RT Na–S)batteries are receiving increasing attention as promising energy storage systems.However,the volume expansion of sulfur and the shuttle effect of polysulfides are the biggest obstacles to their development.In this study,a 3D porous aerogel(hybridized by Ti_(3)C_(2)T_(x)MXene and rGO)adhered with cobalt nanoparticles(MG-Co)is applied to RT Na–S batteries.
基金support from the National Natural Science Foundation of China(No.21773188 and No.21972111)Fundamental Research Funds for the Central Universities(XDJK2019AA002)the Postgraduate Tutor Team Building Project(XYDS201911).
文摘Prussian blue analogues(PBAs)as a kind of promising cathode material for sodium-ion batteries(SIBs)have attracted much attention due to their low price and open three-dimensional(3D)channel structure.Here,a facile wet-chemical method is used to synthesize a nano-sized NiFe-PBA compound.The as-syn thesized NiFe-PBA not only exhibits good structural stability but also demonstrates impressive electro chemical performance when it is used as a cathode in SIBs.Both liquid-state and solid-state sodium-ion batteries(SSIBs)demonstrate excellent cycling stability with a capacity retention of 85.8%and 86.7%,respectively,after 1120 cycles.
基金sponsored financially by the National Natural Science Foundation of China (No.91545103 and 21273071)the Science and Technology Commission of Shanghai Municipality (13JC1401902)
基金financially supported by the National Key Research and Development Program of China(No.2016YFC0204300)the National Natural Science Foundation of China(Nos.21477036 and 21777043)。
文摘La/Ce_(0.5)Mn_(0.5) catalysts prepared by wetness impregnation of Ce_(_(0.5))Mn_(_(0.5)) with La(NO_(3))_(3)(aq) were used in catalytic oxidation of ethyl acetate.Characterization by X-ray diffractometer(XRD),H2 temperature programmed reduction(H2-TPR),X-ray photoelectron spectroscopy(XPS) and Raman shows that La/Ce_(0.5)Mn_(0.5) catalysts have fluorite-like structure.LalCe_(0.5)Mn_(0.5) catalyst presents high activity with T90(the temperature needed for 90% conversion) of 200℃,where ethyl acetate is almost completely converted into CO_(2).The conversion at 195℃ maintains at 80% for at least 100 h.The intermediates were mainly ethanol and acetaldehyde whose amounts are below250 × 10^(-6) and 16 × 10^(-6),respectively.In situ FTIR indicates that the modes of dissociative adsorption of ethyl acetate are related to surface oxygen species,which affect the stability of catalysts and the selectivity for ethanol and acetaldehyde intermediates.
基金financially supported by the National Basic Research Program of China(2010CB732300)the National Key Technologies R&D Program of China(2007BAJ03B01)
文摘Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient temperature.The textural and surface properties of the activated carbons were characterized by nitrogen adsorption,temperature-programmed desorption（TPD）and Boehm titration.The activated carbon support with meso-and macropores,and oxygen-functional groups performs higher CS2 removal ability at ambient temperature.The effects of flow rate,CS2 inlet concentration,temperature and relative humidity on CS2 removal were also investigated.High efficient removal is obtained at temperature of 50-C,space velocity of 2000 h-1,inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20%with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.
基金supported by National Basic Research Program of China(No.2005CB724105)National Natural Science Foundation of China (No.10477010)National High Technical Research and Development Program of China(No.2007AA04Z141)
文摘Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHTC） between the surface of slab casting and inner mold. Calculated temperature dependent values of IHTC were obtained from a numerical solution. The calculated temperatures agreed well with the measurement of cooling profile.
基金Supported by the National Natural Science Foundation of China （20706013, 20736002）, Program for Changjiang Scholars and Innovative Research Team in University （IRT0721）, the 111 Project （B08021） and National University of Singapore.
文摘The interaction of DNA with cationic gemini suffactant trimethylene-1,3-bis （dodecyl dimethyl-ammonium bromide） （12-3-12） and anionic surfactant sodium dodecyl sulfate （SDS） mixed system has been investigated by measuring the fluorescence, zeta potential, UV-Vis spectrum, and circular dichroism. In the absence of SDS, owing to the electrostatic and hydrophobic interactions, 12-3-12 forms micelle-like structure on the DNA chain before the micellization in bulk phase. For the mixed system of 12-3-12 and SDS, the negative charges on SDS can compete against DNA to bind with cationic 12-3-12 because of the stronger interaction between oppositely charged surfactants, and thus, the catanionic mixed micelles are formed before the formation of DNA/12-3-12 complexes. There-after, the positive charges on the mixed micelles bind with DNA, and thus, the change of the zeta potential from negative to positive is distinctly different from the system without SDS. Meanwhile, the existence of SDS postpones the exclusion of ethidium bromide （EB） from DNA/EB complexes. The conformation of DNA undergoes a change from native B-form to chiral ψ-phase as binding with 12-3-12 process. Upon adding SDS to the DNA/12-3-12 complex solution, however, DNA is released to the bulk and the ψ-phase returns to B-form again.
基金Project supported financially by the National Key Research and Development Program of China(2016YFC0204300)the National Natural Science Foundation of China(21976057,21922602)the Shanghai“Pujiang”Program(18PJD011)。
文摘The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence of water on Pd/CeO2-C;but a decrease is found on Pd/CeO2-R.Catalyst characterization reveals that Pd is mainly in the form of solid solution(PdxCe1-xO2-σ)on Pd/CeO2-R and a mixture of metal and PdxCe1-xO2-σsolid solution on Pd/CeO2-C.The strong interaction between Pd and CeO2-R results in the form of stable bidentate carbonates species;while the relatively weak interaction between Pd and CeO2-C leads to the produce of unstable monodentate carbonates species.The effects of water on CO oxidation activity closely relate with the Pd chemical state and the types of carbonates species.Water restrains CO adsorption on PdxCe1-xO2-σsolid solution,but it has negligent effects on metallic Pd species.In the presence of water,bidentate carbonates species remains stable but the decrease in the amount of monodentate carbonates species is observed.
基金the financial support of the project from the Natural Science Foundation of Jiangsu Province of China(No.BK2010392)the Innovation Foundation of Southeast University(No.3212000502)the Opening Project of Jiangsu Key Laboratory of Advanced Materials
文摘Microstructures and precipitation behaviours of Mg94Y4Zn2 （at. %） extruded alloy during solution treatment and ageing processes were investigated. Three major phases were observed in the as-cast Ug94Zn2Y4 alloy：α-Mg, block shaped 1 8R long period stacking ordered （LPSO） phase and Mg24Y5 cuboid particles. After homogenization and extrusion, the block shaped LPSO phase changed into plate-like shape aligned along the direction of extrusion. During solution treatment, a small fraction of LPSO phase was transformed from 18R structure to 14H type. The nano-scale β＇ phase with its close-packed planes being perpendicular to the direction of both α-Mg and LPSO structure was precipitated at ageing stage. The coexistence of β＇ and LPSO phase contributes to the strengthening of the alloy, with microhardness for the matrix and LPSO structures reaching 145.8 and 155,0 HV, respectively.
基金supported by the National Natural Science Foundation of China(Nos.20736002,20706013)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0721)the 111 Project(No.B08021).
文摘Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 V of DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction or partly turned into solution, while for the gels. with higher polyacrylamide concentration, a complete gel-sol transition was observed in a short time.
