Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts in metal-air batteries.However,the active sites in def...Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts in metal-air batteries.However,the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage,leading to rapid degradation of activity.Herein,we design a van der Waals heterostructure comprised of vitamin C(VC)and defective carbon(DC)to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst.The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation,thus significantly enhancing the electrochemical durability and storage anti-aging performance.Moreover,the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR.These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations.It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up,and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent.Furthermore,the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.展开更多
Nanostructured silicon has generated significant excitement for use as the anode material for lithium-ion batteries; however, more effort is needed to produce nanostructured silicon in a scalable fashion and with good...Nanostructured silicon has generated significant excitement for use as the anode material for lithium-ion batteries; however, more effort is needed to produce nanostructured silicon in a scalable fashion and with good performance. Here, we present a direct preparation of porous silicon nanoparticles as a new kind of nanostructured silicon using a novel two-step approach combining controlled boron doping and facile electroless etching. The porous silicon nanoparticles have been successfully used as high performance lithium-ion battery anodes, with capacities around 1,400 mA.h/g achieved at a current rate of 1 A/g, and 1,000 mA.h/g achieved at 2 A/g, and stable operation when combined with reduced graphene oxide and tested over up to 200 cycles. We attribute the overall good performance to the combination of porous silicon that can accommodate large volume change during cycling and provide large surface area accessible to electrolyte, and reduced graphene oxide that can serve as an elastic and electrically conductive matrix for the porous silicon nanoparticles.展开更多
The preparation of graphene with high quality serves as a prerequisite for its usage.Traditional methods of graphene production,represented by liquid-phase exfoliation and chemical vapor deposition,either sacrifice th...The preparation of graphene with high quality serves as a prerequisite for its usage.Traditional methods of graphene production,represented by liquid-phase exfoliation and chemical vapor deposition,either sacrifice the quality and purity of graphene or are limited by the substrate and catalyst.Developing simple and scalable preparation methods of high-quality and high-purity graphene remains a big challenge.Herein,we have reviewed the gas-phase methods including carbonization,combustion,arc discharge,and atmospheric plasma for scalable preparation of free-standing graphene,which are catalyst-,substrate-,solvent-free,and without the need for complex post-treatment methods.The obtained graphene exhibits characteristics of high quality and high purity.Moreover,applications of free-standing graphene were also summarized.Finally,perspectives on opportunities and challenges of free-standing graphene have been discussed.展开更多
This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D...This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D)materials,especially transition-metal dichalcogenides(TMDs),have attracted great interest in research.The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications,such as nanoelectronics and optoelectronics.One-dimensional(1D)nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures,providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality.The natural alignment of zigzag(ZZ)PtSe_(2) nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy(ARPRS),and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory(DFT).Back-gate field-effect transistors(FETs)are also constructed of unidirectional PtSe_(2) nanoribbons to investigate their anisotropic electrical properties,which align with the results of the projected density of states(DOS)calculations.This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives.展开更多
Large-scale production of unconventional phase-controlled telluride catalysts in a simple and fast manner still poses a great challenge.Herein,we develop a superfast tellurizing synthesis method that can quickly prepa...Large-scale production of unconventional phase-controlled telluride catalysts in a simple and fast manner still poses a great challenge.Herein,we develop a superfast tellurizing synthesis method that can quickly prepare unconventional phase-controlled palladium telluride nanoparticles(Pd-Te NPs)on carbon nanotubes(CNTs)(i.e.,PdTe/CNT,Pd_(20)Te_(7)/CNT)in 60 s.By merely tuning the mass of the tellurium precursors under the same conditions,fine(about 5.5 nm)and high-yield(about 90%)hexagonal structured PdTe/CNT and rhombohedral structured Pd_(20)Te_(7)/CNT can be precisely synthesized.The hexagonal structured PdTe/CNT exhibits excellent performance for glycerol oxidation reaction(GOR)and ethylene glycol oxidation reaction(EGOR).Specifically,the highest current density for GOR is 2.72 A mgPd^(-1),which is 1.9-fold higher than that of rhombohedral structured Pd_(20)Te_(7)/CNT,and 2.8-fold higher than that of Pd/CNT.It also outperforms most catalysts reported in GOR.Meanwhile,the specific activity for EGOR is 3.65 A mgPd^(-1),which is 2.1 and 3.9 times higher than those of rhombohedral structured Pd_(20)Te_(7)/CNT and Pd/CNT.We hope that this work can provide guidance for the preparation of crystalline phase-controlled telluride catalysts via new tellurization and inspire the application of crystalline phasecontrolled materials.展开更多
基金financially supported by the National Natural Science Foundation of China (51874197)the Natural Science Foundation of Shanghai (21ZR1429400,22ZR1429700)。
文摘Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts in metal-air batteries.However,the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage,leading to rapid degradation of activity.Herein,we design a van der Waals heterostructure comprised of vitamin C(VC)and defective carbon(DC)to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst.The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation,thus significantly enhancing the electrochemical durability and storage anti-aging performance.Moreover,the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR.These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations.It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up,and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent.Furthermore,the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.
文摘Nanostructured silicon has generated significant excitement for use as the anode material for lithium-ion batteries; however, more effort is needed to produce nanostructured silicon in a scalable fashion and with good performance. Here, we present a direct preparation of porous silicon nanoparticles as a new kind of nanostructured silicon using a novel two-step approach combining controlled boron doping and facile electroless etching. The porous silicon nanoparticles have been successfully used as high performance lithium-ion battery anodes, with capacities around 1,400 mA.h/g achieved at a current rate of 1 A/g, and 1,000 mA.h/g achieved at 2 A/g, and stable operation when combined with reduced graphene oxide and tested over up to 200 cycles. We attribute the overall good performance to the combination of porous silicon that can accommodate large volume change during cycling and provide large surface area accessible to electrolyte, and reduced graphene oxide that can serve as an elastic and electrically conductive matrix for the porous silicon nanoparticles.
基金This research was supported by the Ministry of Science and Technology of China(2016YFA0200101)the National Natural Science Foundation of China(grant no.51720105003).
文摘The preparation of graphene with high quality serves as a prerequisite for its usage.Traditional methods of graphene production,represented by liquid-phase exfoliation and chemical vapor deposition,either sacrifice the quality and purity of graphene or are limited by the substrate and catalyst.Developing simple and scalable preparation methods of high-quality and high-purity graphene remains a big challenge.Herein,we have reviewed the gas-phase methods including carbonization,combustion,arc discharge,and atmospheric plasma for scalable preparation of free-standing graphene,which are catalyst-,substrate-,solvent-free,and without the need for complex post-treatment methods.The obtained graphene exhibits characteristics of high quality and high purity.Moreover,applications of free-standing graphene were also summarized.Finally,perspectives on opportunities and challenges of free-standing graphene have been discussed.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Nos.52072204 and 62104017)the National Postdoctoral Program for Innovative Talents of China(No.BX20200049)China Postdoctoral Science Foundation(No.2021M690013).
文摘This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D)materials,especially transition-metal dichalcogenides(TMDs),have attracted great interest in research.The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications,such as nanoelectronics and optoelectronics.One-dimensional(1D)nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures,providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality.The natural alignment of zigzag(ZZ)PtSe_(2) nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy(ARPRS),and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory(DFT).Back-gate field-effect transistors(FETs)are also constructed of unidirectional PtSe_(2) nanoribbons to investigate their anisotropic electrical properties,which align with the results of the projected density of states(DOS)calculations.This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives.
基金supported by the National Natural Science Foundation of China(51772162,22001143,and 52072197)the Youth Innovation and Technology Foundation of Shandong Higher Education Institutions,China(2019KJC004)+4 种基金the Outstanding Youth Foundation of Shandong Province,China(ZR2019JQ14)Taishan Scholar Young Talent Program(tsqn201909114 and tsqn201909123)the Natural Science Foundation of Shandong Province(ZR2020YQ34)the Major Scientific and Technological Innovation Project(2019JZZY020405)the Major Basic Research Program of Natural Science Foundation of Shandong Province(ZR2020ZD09)。
文摘Large-scale production of unconventional phase-controlled telluride catalysts in a simple and fast manner still poses a great challenge.Herein,we develop a superfast tellurizing synthesis method that can quickly prepare unconventional phase-controlled palladium telluride nanoparticles(Pd-Te NPs)on carbon nanotubes(CNTs)(i.e.,PdTe/CNT,Pd_(20)Te_(7)/CNT)in 60 s.By merely tuning the mass of the tellurium precursors under the same conditions,fine(about 5.5 nm)and high-yield(about 90%)hexagonal structured PdTe/CNT and rhombohedral structured Pd_(20)Te_(7)/CNT can be precisely synthesized.The hexagonal structured PdTe/CNT exhibits excellent performance for glycerol oxidation reaction(GOR)and ethylene glycol oxidation reaction(EGOR).Specifically,the highest current density for GOR is 2.72 A mgPd^(-1),which is 1.9-fold higher than that of rhombohedral structured Pd_(20)Te_(7)/CNT,and 2.8-fold higher than that of Pd/CNT.It also outperforms most catalysts reported in GOR.Meanwhile,the specific activity for EGOR is 3.65 A mgPd^(-1),which is 2.1 and 3.9 times higher than those of rhombohedral structured Pd_(20)Te_(7)/CNT and Pd/CNT.We hope that this work can provide guidance for the preparation of crystalline phase-controlled telluride catalysts via new tellurization and inspire the application of crystalline phasecontrolled materials.
