A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxia...A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxial tensile test was conducted to investigate the effect of fiber length and natural aging factor on the tensile properties of the PMFSS. Results indicated that, under given stress, the increase of fiber length helped reinforce the tensile strength. The elongation of the PMFSS with medium length fiber of 15 mm exhibited the optimal performance, reaching about 13.5%. After natural aging treatment for a month, the tensile strength of PMFSS significantly decreased, but the change of elongation was negligible except for the one with the shortest fiber length of 5 mm, whose elongation was effectively improved. The morphological fracture features of PMFSSs were also characterized.展开更多
An analysis is carried out for dual solutions of the boundary layer flow of Maxwell fluid over a permeable shrinking sheet. In the investigation, a constant wall mass transfer is considered. With the help of similarit...An analysis is carried out for dual solutions of the boundary layer flow of Maxwell fluid over a permeable shrinking sheet. In the investigation, a constant wall mass transfer is considered. With the help of similarity transformations, the governing partial differential equations（PDEs） are converted into a nonlinear self-similar ordinary differential equation（ODE）. For the numerical solution of transformed self-similar ODE, the shooting method is applied. The study reveals that the steady flow of Maxwell fluid is possible with a smaller amount of imposed mass suction compared with the viscous fluid flow. Dual solutions for the velocity distribution are obtained. Also, the increase of Deborah number reduces the boundary layer thickness for both solutions.展开更多
Hexagonal porous Nb2O5 was synthesized for the first time via a facile solid-state reaction.The structure and electrochemical properties have been optimized through tuning heating temperature.X-ray diffraction results...Hexagonal porous Nb2O5 was synthesized for the first time via a facile solid-state reaction.The structure and electrochemical properties have been optimized through tuning heating temperature.X-ray diffraction results indicate that pseudo hexagonal Nb2O5(TT-Nb2O5)and orthorhombic Nb2O5 have been synthesized at different temperatures.Hexagonal sheet and porous structure of Nb2O5 were characterized by scanning electron microscopy and N2-adsorption-desorption isotherms.The as-prepared TT-Nb2O5(heated at 600℃)shows the best performance with a remarkable charge capacity of 178 mA∙h/g at 0.2C,which is higher than that of T-Nb2O5.Even at 20℃,TT-Nb2O5 offers unprecedented rate capability up to 86 mA∙h/g.The high rate capacity is due to pseudocapacitive Li+intercalation mechanism of TT-Nb2O5.The reported results demonstrate that Nb2O5 with good crystal structure and high specific surface area is a powerful composite design for high-rate and safe anode materials.展开更多
Carbon-encapsulated Fe/Fe_(3)C nanoparticles embedded in porous carbon sheets(Fe/Fe_(3)C@PCS)were fabricated by a one step carbothermic reduction,using natural abundant biomass derivatives.Batch experimental results s...Carbon-encapsulated Fe/Fe_(3)C nanoparticles embedded in porous carbon sheets(Fe/Fe_(3)C@PCS)were fabricated by a one step carbothermic reduction,using natural abundant biomass derivatives.Batch experimental results showed that Fe/Fe_(3)C@PCS could effectively remove the radionuclide U(VI)from simulated wastewater in the presence of carbonate or calcium under laboratory conditions with reduced cost,improved activity and enhanced kinetics.Compared with activated carbon(AC),Fe/Fe_(3)C@PCS is more efficient,and can remove U(VI)quantitatively at an initial concentration of up to 140 mg L^(−1).The major reaction pathway involved the reduction of U(VI)to the insoluble U(IV)species as identified by X-ray photoelectron spectroscopy(XPS)analysis.This study demonstrated the potential application of Fe/Fe_(3)C@PCS as a low cost and effective remediation strategy for U-contaminated wastewater cleanup.展开更多
High energy density,stable,and inexpensive electrode materials have the potential to improve the performance of lithium-sulfur(Li-S)batteries.Developing high porosity,high conductivity,and a network framework for mult...High energy density,stable,and inexpensive electrode materials have the potential to improve the performance of lithium-sulfur(Li-S)batteries.Developing high porosity,high conductivity,and a network framework for multidirectional ion transfer in Li-S batteries,on the other hand,remains a significant challenge.Nitrogen and phosphorus co-doped porous carbon sheets(PCS900)are designed and synthesized here with high porosity and abundant active sites.PCS900 can withstand high sulphur loading while also providing multidirectional ion transport channels.Density functional theory(DFT)calculations indicate that nitrogen and phosphorus co-dopants play an important role in suppressing the shuttle effect via the chemical interaction between sulfur and the carbon framework.At a current density of 1 C,the PCS900/S electrode has an initial specific capacity of 737 mA h g^(-1),and the average capacity decay rate per 500 cycles is as low as 0.079%.Furthermore,the heat released during the discharging process is greater than the heat released during the charging process due to the combination of in situ XRD and microcalorimetry techniques.展开更多
The optimization of the electronic structure and increased number of exposed surface sites represent a promising direction for enhancing the activity of Ni-based catalysts for urea oxidation reaction(UOR)-assisted ele...The optimization of the electronic structure and increased number of exposed surface sites represent a promising direction for enhancing the activity of Ni-based catalysts for urea oxidation reaction(UOR)-assisted electrolysis.Herein,we have reported the designed synthesis of 2D porous NiCo alloy thin sheets(NiCo/C)based on NaCl-induced transformation of the EDTA-NiCo complex for the effective UORassisted hydrogen evolution reaction(HER).The porous and thin-sheet structure endows a large specific surface area of 141.59 m^(2) g^(−1),greatly enhancing the exposure of active sites.Electron transfer from Co to Ni can optimize the electronic properties of the Ni sites,decreasing the energy barrier and accelerating the reaction kinetics for the UOR.The catalyst shows a low UOR potential of 1.30 V at a current density of 10 mA cm^(−2),which is much lower than the traditional oxygen evolution reaction(1.51 V).In situ impedance/infrared spectroscopy indicates the fast UOR process and a more environmentally sustainable“carbonate”pathway.The catalyst also shows a low HER overpotential of 30 mV at a current density of 10 mA cm^(−2),being comparable to Pt/C.A urea-assisted H2 production cell based on NiCo/C requires only 1.38 V at a current density of 10 mA cm^(−2),which is superior to the Pt/C||uO_(2) cell(1.45 V).展开更多
The unsteady mixed convection squeezing flow of an incompressible Newtonian fluid between two vertical parallel planes is discussed. The fluid is electrically conducting. The governing equations are transformed into o...The unsteady mixed convection squeezing flow of an incompressible Newtonian fluid between two vertical parallel planes is discussed. The fluid is electrically conducting. The governing equations are transformed into ordinary differential equations （ODEs） by appropriate transformations. The transformed equations are solved successfully by a modern and powerful technique. The effects of the emerging parameters on the flow and heat transfer characteristics are studied and examined. The values of the skin friction coefficient and the local Nusselt number are tabulated and analyzed.展开更多
Non-precious metal Fe-N-C materials are considered one of the promising substitutes for the Pt/C catalyst toward the oxygen reduction reaction(ORR).However,they still suffer from rapid stability reduction caused by th...Non-precious metal Fe-N-C materials are considered one of the promising substitutes for the Pt/C catalyst toward the oxygen reduction reaction(ORR).However,they still suffer from rapid stability reduction caused by the severe Fenton reaction in the ORR process.Here we report a supramolecular-gel-pyrolysis(SGP)method to design a non-noble CeO_(2)/Ce-N-C composite with a hierarchically porous carbon sheet-network structure.展开更多
基金Projects(51475172,51275180,51375177) supported by the National Natural Science Foundation of ChinaProject(S2013040016899) supported by the Natural Science Foundation of Guangdong Province,ChinaProjects(2013ZM0003,2013ZZ017) supported by the Fundamental Research Funds for the Central Universities,South China University of Technology,China
文摘A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxial tensile test was conducted to investigate the effect of fiber length and natural aging factor on the tensile properties of the PMFSS. Results indicated that, under given stress, the increase of fiber length helped reinforce the tensile strength. The elongation of the PMFSS with medium length fiber of 15 mm exhibited the optimal performance, reaching about 13.5%. After natural aging treatment for a month, the tensile strength of PMFSS significantly decreased, but the change of elongation was negligible except for the one with the shortest fiber length of 5 mm, whose elongation was effectively improved. The morphological fracture features of PMFSSs were also characterized.
基金the financial support of National Board for Higher Mathematics(NBHM),DAE,Mumbai,Indiapartially supported by Deanship of Scientific Research(DSR),King Abdulaziz University,Jeddah,Saudi Arabia
文摘An analysis is carried out for dual solutions of the boundary layer flow of Maxwell fluid over a permeable shrinking sheet. In the investigation, a constant wall mass transfer is considered. With the help of similarity transformations, the governing partial differential equations（PDEs） are converted into a nonlinear self-similar ordinary differential equation（ODE）. For the numerical solution of transformed self-similar ODE, the shooting method is applied. The study reveals that the steady flow of Maxwell fluid is possible with a smaller amount of imposed mass suction compared with the viscous fluid flow. Dual solutions for the velocity distribution are obtained. Also, the increase of Deborah number reduces the boundary layer thickness for both solutions.
基金Projects(51974137,51774150)supported by the National Natural Science Foundation of ChinaProject(2020M671361)supported by China Postdoctoral Science Foundation。
文摘Hexagonal porous Nb2O5 was synthesized for the first time via a facile solid-state reaction.The structure and electrochemical properties have been optimized through tuning heating temperature.X-ray diffraction results indicate that pseudo hexagonal Nb2O5(TT-Nb2O5)and orthorhombic Nb2O5 have been synthesized at different temperatures.Hexagonal sheet and porous structure of Nb2O5 were characterized by scanning electron microscopy and N2-adsorption-desorption isotherms.The as-prepared TT-Nb2O5(heated at 600℃)shows the best performance with a remarkable charge capacity of 178 mA∙h/g at 0.2C,which is higher than that of T-Nb2O5.Even at 20℃,TT-Nb2O5 offers unprecedented rate capability up to 86 mA∙h/g.The high rate capacity is due to pseudocapacitive Li+intercalation mechanism of TT-Nb2O5.The reported results demonstrate that Nb2O5 with good crystal structure and high specific surface area is a powerful composite design for high-rate and safe anode materials.
基金the National Natural Science Foundation of China(21207136,21225730 and 91326202)the Ministry of Science and Technology of China(2011CB933700)the Hefei Center for Physical Science and Technology(2012FXZY005).
文摘Carbon-encapsulated Fe/Fe_(3)C nanoparticles embedded in porous carbon sheets(Fe/Fe_(3)C@PCS)were fabricated by a one step carbothermic reduction,using natural abundant biomass derivatives.Batch experimental results showed that Fe/Fe_(3)C@PCS could effectively remove the radionuclide U(VI)from simulated wastewater in the presence of carbonate or calcium under laboratory conditions with reduced cost,improved activity and enhanced kinetics.Compared with activated carbon(AC),Fe/Fe_(3)C@PCS is more efficient,and can remove U(VI)quantitatively at an initial concentration of up to 140 mg L^(−1).The major reaction pathway involved the reduction of U(VI)to the insoluble U(IV)species as identified by X-ray photoelectron spectroscopy(XPS)analysis.This study demonstrated the potential application of Fe/Fe_(3)C@PCS as a low cost and effective remediation strategy for U-contaminated wastewater cleanup.
基金supported by the National Natural Science Foundation of China(U20A20237,52371218,51871065,52271205,51971068 and 21864009)Science and Technology Development Project of Guilin(20210102-4 and 20210216-1)+3 种基金Scientific Research and Technology Development Program of Guangxi(AA19182014,AD17195073,AA17202030-1 and AB21220027)Guangxi Postdoctoral Foundation,Guangxi Bagui Scholar Foundation,Guilin Lijiang Scholar Foundation,Guangxi Collaborative Innovation Centre of Structure and Property for New Energy and Materials,Guangxi Advanced Functional Materials Foundation and Application Talents Small Highlands,Chinesisch-Deutsche Kooperationsgruppe(GZ1528)the Guangxi Natural Science Foundation(2018GXNSFAA281197)The Basic Ability Enhancement Program for Young and Middle-aged Teachers of Guangxi(2023KY0222).
文摘High energy density,stable,and inexpensive electrode materials have the potential to improve the performance of lithium-sulfur(Li-S)batteries.Developing high porosity,high conductivity,and a network framework for multidirectional ion transfer in Li-S batteries,on the other hand,remains a significant challenge.Nitrogen and phosphorus co-doped porous carbon sheets(PCS900)are designed and synthesized here with high porosity and abundant active sites.PCS900 can withstand high sulphur loading while also providing multidirectional ion transport channels.Density functional theory(DFT)calculations indicate that nitrogen and phosphorus co-dopants play an important role in suppressing the shuttle effect via the chemical interaction between sulfur and the carbon framework.At a current density of 1 C,the PCS900/S electrode has an initial specific capacity of 737 mA h g^(-1),and the average capacity decay rate per 500 cycles is as low as 0.079%.Furthermore,the heat released during the discharging process is greater than the heat released during the charging process due to the combination of in situ XRD and microcalorimetry techniques.
基金supported by the National Key R&D Program of China(2022YFA1503003)the National Natural Science Foundation of China(91961111,22271081)+3 种基金the Natural Science Foundation of Heilongjiang Province(ZD2021B003)the Basic Research Fund of Heilongjiang University in Heilongjiang Province(2022-KYYWF-1060)the Postdoctoral Science Foundation of Heilongjiang Province(LBH-Z22240)the Heilongjiang University Excellent Youth Foundation.
文摘The optimization of the electronic structure and increased number of exposed surface sites represent a promising direction for enhancing the activity of Ni-based catalysts for urea oxidation reaction(UOR)-assisted electrolysis.Herein,we have reported the designed synthesis of 2D porous NiCo alloy thin sheets(NiCo/C)based on NaCl-induced transformation of the EDTA-NiCo complex for the effective UORassisted hydrogen evolution reaction(HER).The porous and thin-sheet structure endows a large specific surface area of 141.59 m^(2) g^(−1),greatly enhancing the exposure of active sites.Electron transfer from Co to Ni can optimize the electronic properties of the Ni sites,decreasing the energy barrier and accelerating the reaction kinetics for the UOR.The catalyst shows a low UOR potential of 1.30 V at a current density of 10 mA cm^(−2),which is much lower than the traditional oxygen evolution reaction(1.51 V).In situ impedance/infrared spectroscopy indicates the fast UOR process and a more environmentally sustainable“carbonate”pathway.The catalyst also shows a low HER overpotential of 30 mV at a current density of 10 mA cm^(−2),being comparable to Pt/C.A urea-assisted H2 production cell based on NiCo/C requires only 1.38 V at a current density of 10 mA cm^(−2),which is superior to the Pt/C||uO_(2) cell(1.45 V).
文摘The unsteady mixed convection squeezing flow of an incompressible Newtonian fluid between two vertical parallel planes is discussed. The fluid is electrically conducting. The governing equations are transformed into ordinary differential equations （ODEs） by appropriate transformations. The transformed equations are solved successfully by a modern and powerful technique. The effects of the emerging parameters on the flow and heat transfer characteristics are studied and examined. The values of the skin friction coefficient and the local Nusselt number are tabulated and analyzed.
基金supported by the National Natural Science Foundation of China(project no:22275026 and 21805024),the Natural Science Foundation of Chongqing,China(project no:cstc2021jcyj-msxmX0783,cstc2019jscx-msxmX0393 and cstc2018jcyjAX0461)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(project no:KJZD-K202101303,KJQN201901335 and KJQN202001322).
文摘Non-precious metal Fe-N-C materials are considered one of the promising substitutes for the Pt/C catalyst toward the oxygen reduction reaction(ORR).However,they still suffer from rapid stability reduction caused by the severe Fenton reaction in the ORR process.Here we report a supramolecular-gel-pyrolysis(SGP)method to design a non-noble CeO_(2)/Ce-N-C composite with a hierarchically porous carbon sheet-network structure.
