Porous spherical MnCo_(2)S_(4) was synthesized by a simple solvothermal method.Thanks to the well-designedbimetallic composition and the unique porous spherical structure,the MnCo_(2)S_(4) electrode exhibited an excep...Porous spherical MnCo_(2)S_(4) was synthesized by a simple solvothermal method.Thanks to the well-designedbimetallic composition and the unique porous spherical structure,the MnCo_(2)S_(4) electrode exhibited an exceptionalspecific capacitance of 190.8 mAh·g^(-1)at 1 A·g^(-1),greatly higher than the corresponding monometallic sulfides MnS(31.7 mAh·g^(-1))and Co_(3)S_(4)(86.7 mAh·g^(-1)).Impressively,the as-assembled MnCo_(2)S_(4)||porous carbon(PC)hybridsupercapacitor(HSC),showed an outstanding energy density of 76.88 Wh·kg^(-1)at a power density of 374.5 W·kg^(-1),remarkable cyclic performance with a capacity retention of 86.8% after 10000 charge-discharge cycles at 5 A·g^(-1),and excellent Coulombic efficiency of 99.7%.展开更多
Artificial bone with porous structure is crucial for tissue scaffold and clinic implants.Scaffold provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided p...Artificial bone with porous structure is crucial for tissue scaffold and clinic implants.Scaffold provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided process of porous bone modeling was developed which described the design and fabrication of tissue scaffolds by considering intricate architecture,porosity and pore size.To simulate intricate bone structure,different constructive units were presented.In modeling process,bone contour was gotten from computed tomography(CT)images and was divided into two levels.Each level was represented by relatively reconstructive process.Pore size distribution was controlled by using mesh generation.The whole hexahedral mesh was reduced by unit structure,when a 3D mesh with various hexahedral elements was provided.The simulation results show that constructive structure of porous scaffold can meet the needs of clinic implants in accurate and controlled way.展开更多
This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃sp...This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.展开更多
The capacitive performance of carbon materials as supercapacitor electrode is synergistically influenced by the surface porous structure,graphitization structure,and surface atomic doping.However,simple realization of...The capacitive performance of carbon materials as supercapacitor electrode is synergistically influenced by the surface porous structure,graphitization structure,and surface atomic doping.However,simple realization of their synergistic regulation still faces significant challenges.Based on the biological porous structure,heteroatom-rich content and low cost of chestnut,this work adopt chestnut as precursor to prepare carbon electrode,of which the pores,graphitization,and surface atomic doping are synergistically regulated by simply changing the activation temperature.The optimized carbon electrode possesses a hierarchical porous structure with partial graphitization and O and N co doping.Benefited from these merits,the chestnut-derived porous carbon as a supercapacitor electrode,can achieve a high specific capacitance of 328.6 F/g at 1 A/g,which still retains 80.8%when the current density enlarging to 20 A/g.By packaging the symmetric electric double-layer capacitor,the device exhibits a specific capacitance of 63.6 F/g at 1 A/g,delivering an energy density of 12.7 W·h/kg at a power density of 600 W/kg.The stability of the device is tested at a current density of 20 A/g,which shows a capacitance retention rate of up to 90%after 10000 charge-discharge cycles.展开更多
We reported the fabrication of highly porous graphene/TiO2 composite nanofibers in the form of a nonwoven mat by electrospinning followed by calcination in air at 450°C.The graphene can uniformly disperse in high...We reported the fabrication of highly porous graphene/TiO2 composite nanofibers in the form of a nonwoven mat by electrospinning followed by calcination in air at 450°C.The graphene can uniformly disperse in highly porous TiO2 nanofibers.The highly porous graphene/TiO2 composite nanofibers exhibited excellent catalytic activities.The new method for producing graphene/TiO2 composite nanofibers is versatile and can be extended to fabricate various types of metal oxide and graphene nanocomposites.展开更多
Fossil fuel depletion and environmental deterioration have created an urgent need to develop renewable and clean energy.Biomass,a sustainable organic carbon source,can meet the huge demand for energy and chemicals.Amo...Fossil fuel depletion and environmental deterioration have created an urgent need to develop renewable and clean energy.Biomass,a sustainable organic carbon source,can meet the huge demand for energy and chemicals.Among them,5-hydroxymethylfurfural(HMF)is an important biomass-derived platform molecule,which can be converted into various high-value chemicals.One of its oxidation products,2,5-furandicarboxylic acid(FDCA),is expected to replace terephthalic acid as a raw material for the synthesis of bio-based degradable plastics.The electrooxidation of HMF emerges as a promising green route for preparing FDCA due to its advantages of mild conditions,fast reaction rate,and high selectivity.The theoretical potential of the HMF electrooxidation reaction(HMFOR,0.3 V vs.reversible hydrogen electrode,RHE)is also lower than that of the oxygen evolution reaction(OER,1.23 V vs.RHE).Coupling anodic HMFOR with cathodic hydrogen evolution reaction(HER)is expected to simultaneously produce valuable FDCA and reduce the cell voltage of hydrogen(H2)evolution.However,the construction of efficient and stable bifunctional catalysts for HMFOR-assisted H2 production is still challenging.In this study,Co-doped Ni-Mo-O porous nanorods grown on a nickel foam(Co-NiMoO/NF)is prepared by simple hydrothermal and calcination methods for both HMFOR and HER.Results of electrocatalytic studies indicate that Co-NiMoO/NF exhibits enhanced performance for HMFOR(E10/100=1.31/1.37 V vs.RHE)and HER(E−10/−100=−35/−123 mV vs.RHE)and shows durable HMFOR/HER stability.In particular,Co-NiMoO/NF maintains high FDCA selectivity(~99.2%)and Faradaic efficiency(~95.7%)for 40 successive cycles at 1.36 V vs.RHE for HMFOR.Conversely,Co-NiMoO/NF maintains stable operation at−200 mA∙cm^(−2)for 50 h with no significant activity attenuation for HER.When coupled as a bifunctional electrode for overall HMF splitting,Co-NiMoO/NF reaches an electric flux of 50 mA∙cm^(−2)at 1.48 V,which is 290 mV lower than that of the overall water splitting.This confirms that the HMFOR-assisted H2 production over Co-NiMoO/NF significantly reduces the energy consumption.Moreover,the two-electrode system maintains good FDCA selectivity(97.6%)for 10 cycles at 1.45 V,implying good stability of HMFOR-assisted H2 evolution.The remarkable catalytic performance of Co-NiMoO/NF could be due to the introduction of Co,which optimizes the electronic structure of Ni-Mo-O and adsorption behaviors of the reactants,thereby enhancing the intrinsic activity and stability of the catalyst.Meanwhile,the porous nanorod structure enhanced the mass transport of substrates and desorption of bubbles,thereby elevating the HMFOR/HER kinetics.This study provides useful insights for designing efficient and durable bifunctional catalysts for HMFOR and HER.展开更多
A red-blood-cell-like nitrogen-doped porous carbon catalyst with a high nitrogen content(9.81%)and specific surface area(631.46 m^2/g)was prepared by using melamine cyanuric acid and glucose as sacrificial template an...A red-blood-cell-like nitrogen-doped porous carbon catalyst with a high nitrogen content(9.81%)and specific surface area(631.46 m^2/g)was prepared by using melamine cyanuric acid and glucose as sacrificial template and carbon source,respectively.This catalyst has a comparable onset potential and a higher diffusion-limiting current density than the commercial 20 wt%Pt/C catalyst in alkaline electrolyte.The oxygen reduction reaction mechanism catalyzed by this catalyst is mainly through a 4e pathway process.The excellent catalytic activity could origin from the synergistic effect of the in-situ doped nitrogen(up to 9.81%)and three-dimensional(3D)porous network structure with high specific surface area,which is conducive to the exposure of more active sites.It is interesting to note that the catalytic activity of oxygen reduction strongly depends on the proportion of graphic N rather than the total N content.展开更多
Rational design and synthesis of non-precious-metal catalyst plays an important role in improving the activity and stability for oxygen reduction reaction(ORR)but remains a major challenge.In this work,we used a facil...Rational design and synthesis of non-precious-metal catalyst plays an important role in improving the activity and stability for oxygen reduction reaction(ORR)but remains a major challenge.In this work,we used a facile approach to synthesize iron nanoparticles encapsulated in nitrogen-doped porous carbon materials(Fe@N-C)from functionalized metal-organic frameworks(MOFs,MET-6).Embedding Fe nanoparticles into the carbon skeleton increases the graphitization degree and the proportion of graphitic N as well as promotes the formation of mesopores in the catalyst.The Fe@N-C-30 catalyst showed the excellent ORR activity in alkaline solutions(E^(0)=0.97 V vs.RHE,E1/2=0.89 V vs.RHE).Moreover,the Fe@N-C-30 catalyst exhibited better methanol resistance and long-term stability when compared to commercial Pt/C.The superior ORR performance could be attributed to the combination of high electrochemical surface area,relative high portion of graphitic-N,unique porous structures and the synergistic effect between the encapsulated Fe particles and the N-doped carbon layer.This work provides a promising method to construct efficient non-precious-metal ORR catalyst through MOFs.展开更多
An improved design method of pervious concrete was proposed to lower the deviation between the designed and actual porosity and maintain both mechanical property and permeability of pervious concrete. The improved des...An improved design method of pervious concrete was proposed to lower the deviation between the designed and actual porosity and maintain both mechanical property and permeability of pervious concrete. The improved design method is mainly based on the optimal volume ratio of paste to aggregate(VRPA), which was determined by testing the average thickness of cement paste coating aggregate. The performances of pervious concrete designed by the traditional method and the improved one were compared. The results show that with the increase of designed porosity, the reduction of compressive strength and flexural strength of pervious concrete designed by the improved method is significantly smaller than those designed by the traditional one. The maximum deviation between the designed and actual porosity of the pervious concrete by the improved method is only 1.54%, which is far less than 8.7% obtained by the traditional one. Micro-structural analysis shows that the porous distribution of pervious concrete designed by improved method exhibits better uniformity.展开更多
文摘Porous spherical MnCo_(2)S_(4) was synthesized by a simple solvothermal method.Thanks to the well-designedbimetallic composition and the unique porous spherical structure,the MnCo_(2)S_(4) electrode exhibited an exceptionalspecific capacitance of 190.8 mAh·g^(-1)at 1 A·g^(-1),greatly higher than the corresponding monometallic sulfides MnS(31.7 mAh·g^(-1))and Co_(3)S_(4)(86.7 mAh·g^(-1)).Impressively,the as-assembled MnCo_(2)S_(4)||porous carbon(PC)hybridsupercapacitor(HSC),showed an outstanding energy density of 76.88 Wh·kg^(-1)at a power density of 374.5 W·kg^(-1),remarkable cyclic performance with a capacity retention of 86.8% after 10000 charge-discharge cycles at 5 A·g^(-1),and excellent Coulombic efficiency of 99.7%.
基金Project(2011DFB70230)supported by State International Cooperation Program of ChinaProject(N110403003)supported by Basic Research Foundation of Education Ministry of China
文摘Artificial bone with porous structure is crucial for tissue scaffold and clinic implants.Scaffold provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided process of porous bone modeling was developed which described the design and fabrication of tissue scaffolds by considering intricate architecture,porosity and pore size.To simulate intricate bone structure,different constructive units were presented.In modeling process,bone contour was gotten from computed tomography(CT)images and was divided into two levels.Each level was represented by relatively reconstructive process.Pore size distribution was controlled by using mesh generation.The whole hexahedral mesh was reduced by unit structure,when a 3D mesh with various hexahedral elements was provided.The simulation results show that constructive structure of porous scaffold can meet the needs of clinic implants in accurate and controlled way.
文摘This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.
基金Project(2023JJ40040)supported by the Natural Science Foundation of Hunan Province,ChinaProject(502221904)supported by the Project of Innovation-Driven Plan in Central South University,ChinaProject(24C0140)supported by the Scientific Research Fund of Hunan Provincial Education Department,China。
文摘The capacitive performance of carbon materials as supercapacitor electrode is synergistically influenced by the surface porous structure,graphitization structure,and surface atomic doping.However,simple realization of their synergistic regulation still faces significant challenges.Based on the biological porous structure,heteroatom-rich content and low cost of chestnut,this work adopt chestnut as precursor to prepare carbon electrode,of which the pores,graphitization,and surface atomic doping are synergistically regulated by simply changing the activation temperature.The optimized carbon electrode possesses a hierarchical porous structure with partial graphitization and O and N co doping.Benefited from these merits,the chestnut-derived porous carbon as a supercapacitor electrode,can achieve a high specific capacitance of 328.6 F/g at 1 A/g,which still retains 80.8%when the current density enlarging to 20 A/g.By packaging the symmetric electric double-layer capacitor,the device exhibits a specific capacitance of 63.6 F/g at 1 A/g,delivering an energy density of 12.7 W·h/kg at a power density of 600 W/kg.The stability of the device is tested at a current density of 20 A/g,which shows a capacitance retention rate of up to 90%after 10000 charge-discharge cycles.
基金Project(41271332)supported by the National Natural Science Foundation of China
文摘We reported the fabrication of highly porous graphene/TiO2 composite nanofibers in the form of a nonwoven mat by electrospinning followed by calcination in air at 450°C.The graphene can uniformly disperse in highly porous TiO2 nanofibers.The highly porous graphene/TiO2 composite nanofibers exhibited excellent catalytic activities.The new method for producing graphene/TiO2 composite nanofibers is versatile and can be extended to fabricate various types of metal oxide and graphene nanocomposites.
文摘Fossil fuel depletion and environmental deterioration have created an urgent need to develop renewable and clean energy.Biomass,a sustainable organic carbon source,can meet the huge demand for energy and chemicals.Among them,5-hydroxymethylfurfural(HMF)is an important biomass-derived platform molecule,which can be converted into various high-value chemicals.One of its oxidation products,2,5-furandicarboxylic acid(FDCA),is expected to replace terephthalic acid as a raw material for the synthesis of bio-based degradable plastics.The electrooxidation of HMF emerges as a promising green route for preparing FDCA due to its advantages of mild conditions,fast reaction rate,and high selectivity.The theoretical potential of the HMF electrooxidation reaction(HMFOR,0.3 V vs.reversible hydrogen electrode,RHE)is also lower than that of the oxygen evolution reaction(OER,1.23 V vs.RHE).Coupling anodic HMFOR with cathodic hydrogen evolution reaction(HER)is expected to simultaneously produce valuable FDCA and reduce the cell voltage of hydrogen(H2)evolution.However,the construction of efficient and stable bifunctional catalysts for HMFOR-assisted H2 production is still challenging.In this study,Co-doped Ni-Mo-O porous nanorods grown on a nickel foam(Co-NiMoO/NF)is prepared by simple hydrothermal and calcination methods for both HMFOR and HER.Results of electrocatalytic studies indicate that Co-NiMoO/NF exhibits enhanced performance for HMFOR(E10/100=1.31/1.37 V vs.RHE)and HER(E−10/−100=−35/−123 mV vs.RHE)and shows durable HMFOR/HER stability.In particular,Co-NiMoO/NF maintains high FDCA selectivity(~99.2%)and Faradaic efficiency(~95.7%)for 40 successive cycles at 1.36 V vs.RHE for HMFOR.Conversely,Co-NiMoO/NF maintains stable operation at−200 mA∙cm^(−2)for 50 h with no significant activity attenuation for HER.When coupled as a bifunctional electrode for overall HMF splitting,Co-NiMoO/NF reaches an electric flux of 50 mA∙cm^(−2)at 1.48 V,which is 290 mV lower than that of the overall water splitting.This confirms that the HMFOR-assisted H2 production over Co-NiMoO/NF significantly reduces the energy consumption.Moreover,the two-electrode system maintains good FDCA selectivity(97.6%)for 10 cycles at 1.45 V,implying good stability of HMFOR-assisted H2 evolution.The remarkable catalytic performance of Co-NiMoO/NF could be due to the introduction of Co,which optimizes the electronic structure of Ni-Mo-O and adsorption behaviors of the reactants,thereby enhancing the intrinsic activity and stability of the catalyst.Meanwhile,the porous nanorod structure enhanced the mass transport of substrates and desorption of bubbles,thereby elevating the HMFOR/HER kinetics.This study provides useful insights for designing efficient and durable bifunctional catalysts for HMFOR and HER.
基金Projects(21571189,21771062)supported by the National Natural Science Foundation of ChinaProjects(2016TP1007,2017TP1001)supported by the Hunan Provincial Science and Technology Plan,China+1 种基金Project(150110005)supported by the Fundamental Research and Innovation Project for Postgraduate of Hunan Province,ChinaProjects(2016CL04,2017CL17)supported by the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province,China
文摘A red-blood-cell-like nitrogen-doped porous carbon catalyst with a high nitrogen content(9.81%)and specific surface area(631.46 m^2/g)was prepared by using melamine cyanuric acid and glucose as sacrificial template and carbon source,respectively.This catalyst has a comparable onset potential and a higher diffusion-limiting current density than the commercial 20 wt%Pt/C catalyst in alkaline electrolyte.The oxygen reduction reaction mechanism catalyzed by this catalyst is mainly through a 4e pathway process.The excellent catalytic activity could origin from the synergistic effect of the in-situ doped nitrogen(up to 9.81%)and three-dimensional(3D)porous network structure with high specific surface area,which is conducive to the exposure of more active sites.It is interesting to note that the catalytic activity of oxygen reduction strongly depends on the proportion of graphic N rather than the total N content.
基金supported by the National Natural Science Foundation of China(Grants 22002121,22172121)the National Undergraduate Training Program for Innovation and Entrepreneurship(Grant S202210656087).
文摘Rational design and synthesis of non-precious-metal catalyst plays an important role in improving the activity and stability for oxygen reduction reaction(ORR)but remains a major challenge.In this work,we used a facile approach to synthesize iron nanoparticles encapsulated in nitrogen-doped porous carbon materials(Fe@N-C)from functionalized metal-organic frameworks(MOFs,MET-6).Embedding Fe nanoparticles into the carbon skeleton increases the graphitization degree and the proportion of graphitic N as well as promotes the formation of mesopores in the catalyst.The Fe@N-C-30 catalyst showed the excellent ORR activity in alkaline solutions(E^(0)=0.97 V vs.RHE,E1/2=0.89 V vs.RHE).Moreover,the Fe@N-C-30 catalyst exhibited better methanol resistance and long-term stability when compared to commercial Pt/C.The superior ORR performance could be attributed to the combination of high electrochemical surface area,relative high portion of graphitic-N,unique porous structures and the synergistic effect between the encapsulated Fe particles and the N-doped carbon layer.This work provides a promising method to construct efficient non-precious-metal ORR catalyst through MOFs.
基金Projects(51978346,51778302)supported by the National Natural Science Foundation of ChinaProject(202002N3117)supported by the Ningbo Science and Technology Project,China。
文摘An improved design method of pervious concrete was proposed to lower the deviation between the designed and actual porosity and maintain both mechanical property and permeability of pervious concrete. The improved design method is mainly based on the optimal volume ratio of paste to aggregate(VRPA), which was determined by testing the average thickness of cement paste coating aggregate. The performances of pervious concrete designed by the traditional method and the improved one were compared. The results show that with the increase of designed porosity, the reduction of compressive strength and flexural strength of pervious concrete designed by the improved method is significantly smaller than those designed by the traditional one. The maximum deviation between the designed and actual porosity of the pervious concrete by the improved method is only 1.54%, which is far less than 8.7% obtained by the traditional one. Micro-structural analysis shows that the porous distribution of pervious concrete designed by improved method exhibits better uniformity.
