The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30...The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30_x phase can be lowered from 950℃ to 800℃ through direct calcination of multiphase powder with uniform chemical com- position. The stress which is caused by the volume change during synthetic reaction breaks the particles. It facilitates the formation of highly active superfines of superconductor.展开更多
The nature and transformation of each potential hydroxyl species in a Ce-modified Y zeolite during the calcination process have been investigated via the information of the hydroxyl spectra of the samples monitored in...The nature and transformation of each potential hydroxyl species in a Ce-modified Y zeolite during the calcination process have been investigated via the information of the hydroxyl spectra of the samples monitored in real-time via in situ FTIR spectroscopy technology.A thermogravimetric method was also used to identify the elementary transformation processes of the hydroxyl species during the calcination of the zeolite samples.展开更多
Due to the high specific capacity and low cost,transition metal oxides(TMOs)exhibit huge potential as anode materials for high-performance Li-ion batteries.This study presents the facile synthesis,structural study and...Due to the high specific capacity and low cost,transition metal oxides(TMOs)exhibit huge potential as anode materials for high-performance Li-ion batteries.This study presents the facile synthesis,structural study and electrochemical investigation of ZnMn_(2)O_(4)/carbon(ZMO/C)electrodes.Stabilization of the redox reaction and functional loading of conductive carbon are employed to improve their reversible Li^(+)storage performance.In the calcination process with carbon,analyzed via high-temperature X-ray diffraction,the tetragonal ZnMn_(2)O_(4)undergoes a phase change into MnO/ZnO under an inert atmosphere at around 350℃,while the initial ZnMn_(2)O_(4)phase is transformed into Mn_(2.03)O_(4)/ZnO composite phases under air.The influences of the calcinating temperature and carbon loading on electrochemical performance are investigated,and the excellent cycling stability of ZMO/C electrodes is ascribed to the stable redox reaction and carbon loading.This strategy has led to particular improvement in the structural/electrochemical stability and long-term Li^(+)storage for conversion electrodes.展开更多
To effectively treat pollution and overcome the lack of selectivity of TiO_(2)-based photocatalysts,a 1D structure and molecular imprinting technology have been combined to produce TiO_(2)/SiO_(2) hybrid fibers by a s...To effectively treat pollution and overcome the lack of selectivity of TiO_(2)-based photocatalysts,a 1D structure and molecular imprinting technology have been combined to produce TiO_(2)/SiO_(2) hybrid fibers by a simple electrospinning method by directly adding templates into the precursor solution.In our design,TBOT acts as a titanium source and a functional monomer to combine with RhB and generate specific recognition sites,and SiO_(2) plays a role in inhibiting phase transition.The calcination process can not only remove the template and form an imprinting cavity but also enhance the crystallinity of photoca-talysts.The inorganic framework also overcomes the shortcomings of the instability of traditional organic molecularly imprinted layers.In contrast to a nonimprinted sample,imprinted fibers exhibit higher adsorp-tion capacity and selectivity,attributed to the specific combination through hydrogen bonds and space matching effect.The photocatalytic efficiency of the imprinted sample reached 100%within only 15 min,showing excellent photocatalytic performance and high selectivity.This work not only provides a novel,simple method to fabricate TiO_(2) fiber photocatalysts with high selectivity for the first time but also offers new strategies for the effective and selective treatment of pollutants in wastewater.展开更多
The effect of the pore structures of hollow silica–alumina composite spheres on their activity for the hydrolytic dehydrogenation of ammonia borane has been studied.Following a calcination process that resulted in ho...The effect of the pore structures of hollow silica–alumina composite spheres on their activity for the hydrolytic dehydrogenation of ammonia borane has been studied.Following a calcination process that resulted in hollow spheres,the spheres’shells were coated on spherical polystyrene particle templates.The pore structures of the hollow spheres were controlled by adding a surfactant,cetyltrimethylammonium bromide(CTAB);the volume and homogeneity of the mesopores in the shell of the hollow spheres increased with increasing amount of aqueous CTAB solution.The hollow spheres with a large volume and homogeneous mesopores showed high rates of hydrogen evolution from aqueous ammonia borane solution.The highly active hollow spheres prepared with 5 mL of aqueous CTAB solution showed a considerably high turnover frequency(TOF),although the hollow spheres did not have a significantly high BET surface area or a large quantity of acid sites.This suggests that the activity for hydrogen evolution from aqueous ammonia borane solution in the presence of the hollow spheres with homogeneous mesopore structures was unexpectedly high.展开更多
Developing efficient Pt-free electrocatalysts for hydrogen evolution reaction(HER)at all pHs remains challenging for large-scale hydrogen production,especially in alkaline and neutral conditions,because of sluggish wa...Developing efficient Pt-free electrocatalysts for hydrogen evolution reaction(HER)at all pHs remains challenging for large-scale hydrogen production,especially in alkaline and neutral conditions,because of sluggish water dissociation.Herein,the synthesis of novel highly dispersed RuO_(-2) nanoparticles on NiO nanosheet arrays(RuO_(-2)/NiO/NF)with efficient pH-universal HER electrocatalysis via a simple in situ growth and sequential calcination process is reported.The as-prepared RuO_(-2)/NiO/NF nanosheet arrays exhibit outstanding HER performance with overpotentials of 31,66,and 84 mV to deliver 10,100,and 300 mA cm^(-2),respectively,in 1.0 M KOH,outperforming even the commercial Pt/C electrocatalyst.In addition,RuO_(-2)/NiO/NF shows a higher turnover frequency at an overpotential of 100 mV in comparison with Pt/C electrocatalyst.It also requires extremely low overpotentials of 98 mV and 254 mV to afford 300 mA cm^(-2) in 0.5 M H_(2)SO_(4) and 1.0 M PBS-neutral solution,respectively.Moreover,RuO_(-2)/NiO/NF can work at 100 mA cm^(-2) for 200 h with negligible decay in 1.0 M KOH.The splendid HER performance can be ascribed to the 3D nanosheet arrays and highly dispersed RuO_(-2) nanoparticles with richly exposed active sites,favoring the efficient electron and mass transfer to the active sites.展开更多
In recent years,carbon dots(CDs)based hybrid nanomaterials have received considerable attention due to their outstanding optical and catalytic properties.Herein,CDs/Fe_(3)O_(4)hybrid nanofibers are prepared via a faci...In recent years,carbon dots(CDs)based hybrid nanomaterials have received considerable attention due to their outstanding optical and catalytic properties.Herein,CDs/Fe_(3)O_(4)hybrid nanofibers are prepared via a facile electrospinning technique combined with a hydrothermal reaction and a thermochemical reduction process.During the synthetic process,α-Fe_(2)O_(3)nanofibers are synthesized via electrospinning followed by a calcination process first.Then CDs modified α-Fe_(2)O_(3)nanofibers can be obtained under a hydrothermal reaction.Finally,the prepared CDs modified α-Fe_(2)O_(3)nanofibers are converted to CDs/Fe_(3)O_(4)hybrid nanofibers through a thermochemical reduction process.The resulting CDs/Fe_(3)O_(4)hybrid nanofibers show a superior peroxidase catalytic activity to individual CDs,α-Fe_(2)O_(3)nanofibers,CDs/α-Fe_(2)O_(3)hybrid nanofibers and commercial Fe_(3)O_(4)nanoparticles.The steady-state kinetic assay exhibits an excellent affinity for TMB with a low Michaelis-Menten constant(Km)value.On the basis of the high peroxidase-like activity of CDs/Fe_(3)O_(4)hybrid nanofibers,a simple approach for the colorimetric detection of H_(2)O_(2)and ascorbic acid(AA)with a low detection limit of 0.917 and 0.285μM,respectively,is developed.This work inspires researchers to develop functional hybrid nanomaterials for fabricating superior biomimetic catalysts and extends their applications in biosensors and environmental monitoring.展开更多
The electrochemical nitrate reduction reaction(NtRR)under ambient conditions is regarded as a potential approach to achieve NH3 production,which currently heavily relies on the Haber–Bosch process at the cost of a hu...The electrochemical nitrate reduction reaction(NtRR)under ambient conditions is regarded as a potential approach to achieve NH3 production,which currently heavily relies on the Haber–Bosch process at the cost of a huge amount of energy and the massive production of CO_(2).Herein,a flower-like CuCo_(2)O_(4)spinel was synthesized via a two-step urea-assisted hydrothermal treatment and calcination process.展开更多
文摘The synthesis kinetics of YBa_2Cu_30_x supercon- ductor was studied through comparing the calcina- tion (sintering) processes of different kinds of powders. It was shown that the temperature of synthesis of YBa_2Cu_30_x phase can be lowered from 950℃ to 800℃ through direct calcination of multiphase powder with uniform chemical com- position. The stress which is caused by the volume change during synthetic reaction breaks the particles. It facilitates the formation of highly active superfines of superconductor.
基金supported by the National Natural Science Foundation of China(no.U20A20120 and 21902068)by the China National Petroleum Corporation(2021DJ0701).
文摘The nature and transformation of each potential hydroxyl species in a Ce-modified Y zeolite during the calcination process have been investigated via the information of the hydroxyl spectra of the samples monitored in real-time via in situ FTIR spectroscopy technology.A thermogravimetric method was also used to identify the elementary transformation processes of the hydroxyl species during the calcination of the zeolite samples.
基金support of this research by the China Scholarship Council(CSC grant number:201506880029)supports from Geckle Udo(SEM measurement),Liuda Mereacrea(TGA measurement)from the Institute for Applied Materials(IAM-ESS),and Karlsruhe Institute of Technology(KIT)are also greatly acknowledged.
文摘Due to the high specific capacity and low cost,transition metal oxides(TMOs)exhibit huge potential as anode materials for high-performance Li-ion batteries.This study presents the facile synthesis,structural study and electrochemical investigation of ZnMn_(2)O_(4)/carbon(ZMO/C)electrodes.Stabilization of the redox reaction and functional loading of conductive carbon are employed to improve their reversible Li^(+)storage performance.In the calcination process with carbon,analyzed via high-temperature X-ray diffraction,the tetragonal ZnMn_(2)O_(4)undergoes a phase change into MnO/ZnO under an inert atmosphere at around 350℃,while the initial ZnMn_(2)O_(4)phase is transformed into Mn_(2.03)O_(4)/ZnO composite phases under air.The influences of the calcinating temperature and carbon loading on electrochemical performance are investigated,and the excellent cycling stability of ZMO/C electrodes is ascribed to the stable redox reaction and carbon loading.This strategy has led to particular improvement in the structural/electrochemical stability and long-term Li^(+)storage for conversion electrodes.
基金supported by the National Natural Science Foundation of China(52073120).
文摘To effectively treat pollution and overcome the lack of selectivity of TiO_(2)-based photocatalysts,a 1D structure and molecular imprinting technology have been combined to produce TiO_(2)/SiO_(2) hybrid fibers by a simple electrospinning method by directly adding templates into the precursor solution.In our design,TBOT acts as a titanium source and a functional monomer to combine with RhB and generate specific recognition sites,and SiO_(2) plays a role in inhibiting phase transition.The calcination process can not only remove the template and form an imprinting cavity but also enhance the crystallinity of photoca-talysts.The inorganic framework also overcomes the shortcomings of the instability of traditional organic molecularly imprinted layers.In contrast to a nonimprinted sample,imprinted fibers exhibit higher adsorp-tion capacity and selectivity,attributed to the specific combination through hydrogen bonds and space matching effect.The photocatalytic efficiency of the imprinted sample reached 100%within only 15 min,showing excellent photocatalytic performance and high selectivity.This work not only provides a novel,simple method to fabricate TiO_(2) fiber photocatalysts with high selectivity for the first time but also offers new strategies for the effective and selective treatment of pollutants in wastewater.
基金supported by the University of Tokyo and the microstructural characterization platform of NIMS as a program of“Nanotechnology Platform”of the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japan.We are grateful to Mr Deguchi and Ms Wada for solidstate NMR and Mr Ito for using TEM measurement support.Additionally,we also thank Dr Yoneda for NH3-TPD measurement support.All authors contributed equally to this work.
文摘The effect of the pore structures of hollow silica–alumina composite spheres on their activity for the hydrolytic dehydrogenation of ammonia borane has been studied.Following a calcination process that resulted in hollow spheres,the spheres’shells were coated on spherical polystyrene particle templates.The pore structures of the hollow spheres were controlled by adding a surfactant,cetyltrimethylammonium bromide(CTAB);the volume and homogeneity of the mesopores in the shell of the hollow spheres increased with increasing amount of aqueous CTAB solution.The hollow spheres with a large volume and homogeneous mesopores showed high rates of hydrogen evolution from aqueous ammonia borane solution.The highly active hollow spheres prepared with 5 mL of aqueous CTAB solution showed a considerably high turnover frequency(TOF),although the hollow spheres did not have a significantly high BET surface area or a large quantity of acid sites.This suggests that the activity for hydrogen evolution from aqueous ammonia borane solution in the presence of the hollow spheres with homogeneous mesopore structures was unexpectedly high.
基金supported by the National Key Research and Development Program of China(2022YFA1503400,2016YFB0301600)National Natural Science Foundation of China(21627813).
文摘Developing efficient Pt-free electrocatalysts for hydrogen evolution reaction(HER)at all pHs remains challenging for large-scale hydrogen production,especially in alkaline and neutral conditions,because of sluggish water dissociation.Herein,the synthesis of novel highly dispersed RuO_(-2) nanoparticles on NiO nanosheet arrays(RuO_(-2)/NiO/NF)with efficient pH-universal HER electrocatalysis via a simple in situ growth and sequential calcination process is reported.The as-prepared RuO_(-2)/NiO/NF nanosheet arrays exhibit outstanding HER performance with overpotentials of 31,66,and 84 mV to deliver 10,100,and 300 mA cm^(-2),respectively,in 1.0 M KOH,outperforming even the commercial Pt/C electrocatalyst.In addition,RuO_(-2)/NiO/NF shows a higher turnover frequency at an overpotential of 100 mV in comparison with Pt/C electrocatalyst.It also requires extremely low overpotentials of 98 mV and 254 mV to afford 300 mA cm^(-2) in 0.5 M H_(2)SO_(4) and 1.0 M PBS-neutral solution,respectively.Moreover,RuO_(-2)/NiO/NF can work at 100 mA cm^(-2) for 200 h with negligible decay in 1.0 M KOH.The splendid HER performance can be ascribed to the 3D nanosheet arrays and highly dispersed RuO_(-2) nanoparticles with richly exposed active sites,favoring the efficient electron and mass transfer to the active sites.
基金supported by the research grants from the National Natural Science Foundation of China(51473065 and 21473068).
文摘In recent years,carbon dots(CDs)based hybrid nanomaterials have received considerable attention due to their outstanding optical and catalytic properties.Herein,CDs/Fe_(3)O_(4)hybrid nanofibers are prepared via a facile electrospinning technique combined with a hydrothermal reaction and a thermochemical reduction process.During the synthetic process,α-Fe_(2)O_(3)nanofibers are synthesized via electrospinning followed by a calcination process first.Then CDs modified α-Fe_(2)O_(3)nanofibers can be obtained under a hydrothermal reaction.Finally,the prepared CDs modified α-Fe_(2)O_(3)nanofibers are converted to CDs/Fe_(3)O_(4)hybrid nanofibers through a thermochemical reduction process.The resulting CDs/Fe_(3)O_(4)hybrid nanofibers show a superior peroxidase catalytic activity to individual CDs,α-Fe_(2)O_(3)nanofibers,CDs/α-Fe_(2)O_(3)hybrid nanofibers and commercial Fe_(3)O_(4)nanoparticles.The steady-state kinetic assay exhibits an excellent affinity for TMB with a low Michaelis-Menten constant(Km)value.On the basis of the high peroxidase-like activity of CDs/Fe_(3)O_(4)hybrid nanofibers,a simple approach for the colorimetric detection of H_(2)O_(2)and ascorbic acid(AA)with a low detection limit of 0.917 and 0.285μM,respectively,is developed.This work inspires researchers to develop functional hybrid nanomaterials for fabricating superior biomimetic catalysts and extends their applications in biosensors and environmental monitoring.
基金financially supported by the Natural Science Foundation of Anhui Province(Grant No.2108085QB60 and 2108085QB61)the CASHIPS Director's Fund(Grant No.YZJJ2021QN18 and YZJJ2021QN21)+1 种基金the China Postdoctoral Science Foundation(Grant No.2020M682057)the CAS/SAFEAInternational Partnership Program for Creative Research Teams of Chinese Academy of Sciences,China.
文摘The electrochemical nitrate reduction reaction(NtRR)under ambient conditions is regarded as a potential approach to achieve NH3 production,which currently heavily relies on the Haber–Bosch process at the cost of a huge amount of energy and the massive production of CO_(2).Herein,a flower-like CuCo_(2)O_(4)spinel was synthesized via a two-step urea-assisted hydrothermal treatment and calcination process.
