Rapid capacity decay and sluggish reaction kinetics are major barriers hindering the applications of manganese-based cathode materials for aqueous zinc-ion batteries.Herein,the effects of crystal plane on the in-situ ...Rapid capacity decay and sluggish reaction kinetics are major barriers hindering the applications of manganese-based cathode materials for aqueous zinc-ion batteries.Herein,the effects of crystal plane on the in-situ transformation behavior and electrochemical performance of manganese-based cathode is discussed.A comprehensive discussion manifests that the exposed(100)crystal plane is beneficial to the phase transformation from tunnel-structured MnO_(2) to layer-structured ZnMn_(3)O_(7)·3H_(2)O,which plays a critical role for the high reactivity,high capacity,fast diffusion kinetics and long cycling stability.Additionally,a two-stage zinc storage mechanism can be demonstrated,involving continuous activation reaction and phase transition reaction.As expected,it exhibits a high capacity of 275 mAh g^(-1)at 100 mA g^(-1),a superior durability over 1000 cycles and good rate capability.This study may open new windows toward developing advanced cathodes for ZIBs,and facilitate the applications of ZIBs in large-scale energy storage system.展开更多
The crystal plane plays a very important role in the properties of Ni-rich cathodes.[003]crystallographic texture regulation has been proven to improve structural stability,and yet,the discrepancy of particles with di...The crystal plane plays a very important role in the properties of Ni-rich cathodes.[003]crystallographic texture regulation has been proven to improve structural stability,and yet,the discrepancy of particles with different exposed ratios of[003]in structural attenuation has not been clarified.Herein,we have unraveled comprehensively the structural decay difference for Ni-rich cathodes’primary particles with the different percentages of exposed[003]by regulating the precursor coprecipitation process.The findings based on structural characterization,first-principles calculations,finite element analysis,and electrochemical test reveal that the length and width of particles represent[110]and[003]directions,respectively,and show that cathode particles with a higher[110]/[003]ratio can effectively inhibit structure degradation and intergranular/intragranular crack formation owing to the low oxygen vacancy formation energy on(003)planes and the small local stress on secondary/primary particles.This study may provide guidance for the structural design of layered cathodes.展开更多
For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatme...For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.展开更多
Au nanostructures were prepared on uniform Cu2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAuCl 4 and Cu2O. The compositions and structures were studied by Scanning Electron Micro...Au nanostructures were prepared on uniform Cu2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAuCl 4 and Cu2O. The compositions and structures were studied by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), High-Resolution Transmission Electron Microscope (HRTEM), X-Ray Diffraction (XRD), X-Ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS) and in-situ DRIFTS spectroscopy of CO adsorption. Different from the formation of Au-Cu alloys on Cu2O cubes by the galvanic replacement reaction (ChemNanoMat 2 (2016) 861-865), metallic Au particles and positively-charged Au clusters form on Cu2O octahedra and rhombic dodecahedra at very small Au loadings and only metallic Au particles form at large Au loadings. Metallic Au particles on Cu2O octahedra and rhombic dodecahedra are more active in catalyzing the liquid phase aerobic oxidation reaction of benzyl alcohol than positively-charged Au clusters. These results demonstrate an obvious morphology effect of Cu2O nanocrystals on the liquid-solid interfacial reactions and prove oxide morphology as an effective strategy to tune the surface reactivity and catalytic performance. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Ceria(CeO_(2))nanoparticles were successfully synthesized via a simple complex-precipitation route that employs cerium chloride as cerium source and citric acid as precipitant.The elemental analysis results of carbon,...Ceria(CeO_(2))nanoparticles were successfully synthesized via a simple complex-precipitation route that employs cerium chloride as cerium source and citric acid as precipitant.The elemental analysis results of carbon,hydrogen,oxygen,and cerium in the precursors were calculated,and the results revealed that the precursors were composed of Ce(OH)_(3),Ce(H_(2)Cit)_(3),or CeCit.X-ray diffraction analysis showed that all ceria nanoparticles had a face-centered cubic structure.With the molar ratio of citric acid to Ce^(3)+(n)of 0.25 and pH of 5.5,the specific surface area of the sample reached the maximum value of 83.17 m^(2)/g.Ceria nanoparticles were observed by scanning electron microscopy.Selected area electron diffraction patterns of several samples were obtained by transmission electron microscopy,and the crystal plane spacing of each low-exponent crystal plane was calculated.The ultraviolet(UV)–visible transmittance curve showed that ceria can absorb UV light and pass through visible light.Among all samples,the minimum average transmittance of ultraviolet radiation a(UVA)was 4.42%,and that of ultraviolet radiation b(UVB)was 1.56%.展开更多
Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis di...Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis diffuse reflectance spectra and Mott–Schottky plots show that the band structure of the CaFeOnanorods is narrower than that of the CaFeOnanoparticles synthesized by conventional method. The enhancement of the visible-light absorption is due to narrowness of the band gap in CaFeOnanorods. The appropriate ratio between the molten salt and the CaFeOprecursors plays an important role in inhibiting the growth of the crystals along the(201) plane to give the desired nanorod morphology. This work not only demonstrates that highly pure p-type CaFeOsemiconductor with tunable band structure and morphology could be obtained using the molten salt strategy, but also affirms that the bandgap of a semiconductor may be tunable by monitoring the growth of a particular crystal plane.Furthermore, the facile eutectic molten salt method developed in this work may be further extended to fabricate some other semiconductor nanomaterials with a diversity of morphologies.展开更多
The Fe-Ni-Cr coating laver has been alloyed with 45 steel base metal by transverse.flow type CO_2 gas laser of maximum output 5kW.The characteristics of the melted zone and the es- sence of the“bright band”has been ...The Fe-Ni-Cr coating laver has been alloyed with 45 steel base metal by transverse.flow type CO_2 gas laser of maximum output 5kW.The characteristics of the melted zone and the es- sence of the“bright band”has been investigated using the electron microscopy.The results show that the“bright band”belongs to the melted zone and is a vertical section of the plane crystal,The width of the“bright band”equals the height of the plane crystal,which decreases with the increase of laser beam scanning rate and the decrease of laser power.This has been explained in terms of constitutional supercooling G/R.展开更多
The local structure of the metal single-atom site is closely related to the catalytic activity of metal single-atom catalysts(SACs).However,constructing SACs with homogeneous metal active sites is a challenge due to t...The local structure of the metal single-atom site is closely related to the catalytic activity of metal single-atom catalysts(SACs).However,constructing SACs with homogeneous metal active sites is a challenge due to the surface heterogeneity of the conventional support.Herein,we prepared two Rh1/CeO_(2)SACs(0.5Rh1/r-CeO_(2)and 0.5Rh1/c-CeO_(2),respectively)using two shaped CeO_(2)(rod and cube)exposing different facets,i.e.,CeO_(2)(111)and CeO_(2)(100).In CO oxidation reaction,the T100 of 0.5Rh1/r-CeO_(2)SACs is 120°C,while the T100 of 0.5Rh1/c-CeO_(2)SACs is as high as 200°C.Via in-situ CO diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),we found that the proximity between OH group and Rh single atom on the plane surface plays an important role in the catalytic activity of Rh1/CeO_(2)SAC system in CO oxidation.The Rh single atom trapped at the CeO_(2)(111)crystal surface forms the Rh1(OH)adjacent species,which is not found on the CeO_(2)(100)crystal surface at room temperature.Furthermore,during CO oxidation,the OH group far from Rh single atom on the 0.5Rh1/c-CeO_(2)disappears and forms Rh1(OH)adjacent species when the temperature is above 150°C.The formation of Rh1(OH)adjacentCO intermediate in the reaction is pivotal for the excellent catalytic activity,which explains the difference in the catalytic activity of Rh single atoms on two different CeO_(2)planes.The formed Rh1(OH)adjacent-O-Ce structure exhibits good stability in the reducing atmosphere,maintaining the Rh atomic dispersion after CO oxidation even when pre-reduced at high temperature of 500°C.Density functional theory(DFT)calculations validate the unique activity and reaction path of the intermediate Rh1(OH)adjacentCO species formed.This work demonstrates that the proximity between metal single atom and hydroxyl can determine the formation of active intermediates to affect the catalytic performances in catalysis.展开更多
The catalytic activity of crystallites depends mainly upon the arrangement of surface atoms,the number of dangling bonds,and defect site distribution on different crystal planes.Here,we report the shape-controlled syn...The catalytic activity of crystallites depends mainly upon the arrangement of surface atoms,the number of dangling bonds,and defect site distribution on different crystal planes.Here,we report the shape-controlled synthesis of CuCl crystallites,including tetrahedra,face-centered-etched tetrahedra,tripod dendrites,and tetrapods.These different morphologies of CuCl crystallites expose different proportions of{111}and{110}crystal planes,and materials with a preponderance of{111}crystal planes have better catalytic activity in aniline coupling than those with more{110}planes.展开更多
Cellulose polymerization degree and crystal plane changing are both considered to affect acid hydrolysis,however,it is uncertain to identify which one is more important.In this study,the filter paper was treated with ...Cellulose polymerization degree and crystal plane changing are both considered to affect acid hydrolysis,however,it is uncertain to identify which one is more important.In this study,the filter paper was treated with dilute hydrochloric acid to investigate the cellulose polymerization degree changing,and cotton linter was treated with NaOH for the purpose of changing its crystal plane.Both the treated and untreated samples were hydrolyzed under the condition of 1.0 wt%dilute hydrochloric acid with solid-liquid ratio 1:40 at 140℃for 30 min to compare the hydrolysis effects.It was found that the glucose yield increased from 9.5%to 19.7%when treated with 15%NaOH at 50℃for 30 min,and new crystal planes(1-10)(1-20)appeared after alkali treatment.According to the experimental results,it is concluded that crystal plane plays a vital role in cellulose acid hydrolysis.展开更多
The rapid development of the aerospace and nuclear industries is accompanied by increased exposure to high-energy ionising radiation.Thus,the performance of radiation shielding materials needs to be improved to extend...The rapid development of the aerospace and nuclear industries is accompanied by increased exposure to high-energy ionising radiation.Thus,the performance of radiation shielding materials needs to be improved to extend the service life of detectors and ensure the safety of personnel.The development of novel lightweight materials with high electron density has therefore become urgent to alleviate radiation risks.In this work,new MAPbI_(3)/epoxy(CH 3NH 3PbI 3/epoxy)composites were prepared via a crystal plane engineering strategy.These composites delivered excellent radiation shielding performance against 59.5 keV gamma rays.A high linear attenuation coefficient(1.887 cm−1)and mass attenuation coefficient(1.352 cm2 g−1)were achieved for a representative MAPbI_(3)/epoxy composite,which was 10 times higher than that of the epoxy.Theoretical calculations indicate that the electron density of MAPbI_(3)/epoxy composites significantly increases when the content ratio of the(110)plane in MAPbI_(3) increases.As a result,the chances of collision between the incident gamma rays and electrons in the MAPbI_(3)/epoxy composites were enhanced.The present work provides a novel strategy for designing and developing high-efficiency radiation shielding materials.展开更多
The mechanism of dimethyl carbonate(DMC) formation from CO2 and methanol is investigated using three well-shaped CeO2 catalysts, nanorod, nanocube and octahedron, which are packed with different crystal planes. In s...The mechanism of dimethyl carbonate(DMC) formation from CO2 and methanol is investigated using three well-shaped CeO2 catalysts, nanorod, nanocube and octahedron, which are packed with different crystal planes. In situ Fourier Transform Infrared Spectroscopy(FTIR) is employed to probe each reaction step in the DMC synthesis. The number of –OH groups and the species of CO2 adsorptions on ceria surface have significant influence on the activity of ceria with different morphologies. Rod-ceria has favorable catalytic activity because of the large amount of –OH groups and the formation of bidentate carbonate species.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51932011 and 52072411)Science and technology innovation Program of Hunan Province(Grant no.2021RC3001)Natural Science Foundation of Hunan Province(Grant no.2021JJ20060,2018RS3019 and 2019JJ30033).
文摘Rapid capacity decay and sluggish reaction kinetics are major barriers hindering the applications of manganese-based cathode materials for aqueous zinc-ion batteries.Herein,the effects of crystal plane on the in-situ transformation behavior and electrochemical performance of manganese-based cathode is discussed.A comprehensive discussion manifests that the exposed(100)crystal plane is beneficial to the phase transformation from tunnel-structured MnO_(2) to layer-structured ZnMn_(3)O_(7)·3H_(2)O,which plays a critical role for the high reactivity,high capacity,fast diffusion kinetics and long cycling stability.Additionally,a two-stage zinc storage mechanism can be demonstrated,involving continuous activation reaction and phase transition reaction.As expected,it exhibits a high capacity of 275 mAh g^(-1)at 100 mA g^(-1),a superior durability over 1000 cycles and good rate capability.This study may open new windows toward developing advanced cathodes for ZIBs,and facilitate the applications of ZIBs in large-scale energy storage system.
基金National Natural Science Foundation of China,Grant/Award Numbers:20A20145,21878195,22108183,21975154,22179078Distinguished Young Foundation of Sichuan Province,Grant/Award Number:2020JDJQ0027+7 种基金2020 Strategic cooperation project between Sichuan University and Zigong Municipal People's Government,Grant/Award Number:2020CDZG-09State Key Laboratory of Polymer Materials Engineering,Grant/Award Number:sklpme2020-3-02Sichuan Provincial Department of Science and Technology,Grant/Award Numbers:2020YFG0471,2020YFG0022Sichuan Province Science and Technology Achievement Transfer and Trans-formation Project,Grant/Award Number:21ZHSF0111Sichuan University postdoctoral interdisciplinary Innovation Fund,the State Key Laboratory of Electrical Insulation and Power Equipment,Xi'an Jiaotong University,Grant/Award Number:EIPE22208National Postdoctoral Program for Innovative Talents,Grant/Award Number:BX20200222China Postdoctoral Science Foundation,Grant/Award Numbers:2020M682878,2022M712231Start-up funding of Chemistry and Chemical Engineering Guangdong Laboratory,Grant/Award Number:2122010。
文摘The crystal plane plays a very important role in the properties of Ni-rich cathodes.[003]crystallographic texture regulation has been proven to improve structural stability,and yet,the discrepancy of particles with different exposed ratios of[003]in structural attenuation has not been clarified.Herein,we have unraveled comprehensively the structural decay difference for Ni-rich cathodes’primary particles with the different percentages of exposed[003]by regulating the precursor coprecipitation process.The findings based on structural characterization,first-principles calculations,finite element analysis,and electrochemical test reveal that the length and width of particles represent[110]and[003]directions,respectively,and show that cathode particles with a higher[110]/[003]ratio can effectively inhibit structure degradation and intergranular/intragranular crack formation owing to the low oxygen vacancy formation energy on(003)planes and the small local stress on secondary/primary particles.This study may provide guidance for the structural design of layered cathodes.
基金financialy supported by the National Key R&D Program of China(Grant No.2018YFB0905400)the National Natural Science Foundation of China(Grant Nos.22075331,51702376)+2 种基金the Fundamental Research Funds for the Central Universities(19lgzd02)the Guangdong Pearl River Talents Plan(2019QN01L117)the National Thousand Youth Talents Project of the Chinese Government
文摘For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.
基金supported by the National Basic Research Program of China(2013CB933104)the National Natural Science Foundation of China(21525313,21173204,21373192,U1332113)+1 种基金MOE Fundamental Research Funds for the Central Universities(WK2060030017)Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Au nanostructures were prepared on uniform Cu2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAuCl 4 and Cu2O. The compositions and structures were studied by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), High-Resolution Transmission Electron Microscope (HRTEM), X-Ray Diffraction (XRD), X-Ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS) and in-situ DRIFTS spectroscopy of CO adsorption. Different from the formation of Au-Cu alloys on Cu2O cubes by the galvanic replacement reaction (ChemNanoMat 2 (2016) 861-865), metallic Au particles and positively-charged Au clusters form on Cu2O octahedra and rhombic dodecahedra at very small Au loadings and only metallic Au particles form at large Au loadings. Metallic Au particles on Cu2O octahedra and rhombic dodecahedra are more active in catalyzing the liquid phase aerobic oxidation reaction of benzyl alcohol than positively-charged Au clusters. These results demonstrate an obvious morphology effect of Cu2O nanocrystals on the liquid-solid interfacial reactions and prove oxide morphology as an effective strategy to tune the surface reactivity and catalytic performance. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金financially supported by the Major State Basic Research Development Program of China(No.2012CBA01205)the National Natural Science Foundation of China(No.51274060)。
文摘Ceria(CeO_(2))nanoparticles were successfully synthesized via a simple complex-precipitation route that employs cerium chloride as cerium source and citric acid as precipitant.The elemental analysis results of carbon,hydrogen,oxygen,and cerium in the precursors were calculated,and the results revealed that the precursors were composed of Ce(OH)_(3),Ce(H_(2)Cit)_(3),or CeCit.X-ray diffraction analysis showed that all ceria nanoparticles had a face-centered cubic structure.With the molar ratio of citric acid to Ce^(3)+(n)of 0.25 and pH of 5.5,the specific surface area of the sample reached the maximum value of 83.17 m^(2)/g.Ceria nanoparticles were observed by scanning electron microscopy.Selected area electron diffraction patterns of several samples were obtained by transmission electron microscopy,and the crystal plane spacing of each low-exponent crystal plane was calculated.The ultraviolet(UV)–visible transmittance curve showed that ceria can absorb UV light and pass through visible light.Among all samples,the minimum average transmittance of ultraviolet radiation a(UVA)was 4.42%,and that of ultraviolet radiation b(UVB)was 1.56%.
基金supports from the National Natural Science Foundation of China(nos.21473189 and21503100)the 973 National Basic Research Program of China(no.2014CB239401)the Natural Science Foundation of Jiangxi Province of China(no.20151BAB213010)
文摘Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis diffuse reflectance spectra and Mott–Schottky plots show that the band structure of the CaFeOnanorods is narrower than that of the CaFeOnanoparticles synthesized by conventional method. The enhancement of the visible-light absorption is due to narrowness of the band gap in CaFeOnanorods. The appropriate ratio between the molten salt and the CaFeOprecursors plays an important role in inhibiting the growth of the crystals along the(201) plane to give the desired nanorod morphology. This work not only demonstrates that highly pure p-type CaFeOsemiconductor with tunable band structure and morphology could be obtained using the molten salt strategy, but also affirms that the bandgap of a semiconductor may be tunable by monitoring the growth of a particular crystal plane.Furthermore, the facile eutectic molten salt method developed in this work may be further extended to fabricate some other semiconductor nanomaterials with a diversity of morphologies.
文摘The Fe-Ni-Cr coating laver has been alloyed with 45 steel base metal by transverse.flow type CO_2 gas laser of maximum output 5kW.The characteristics of the melted zone and the es- sence of the“bright band”has been investigated using the electron microscopy.The results show that the“bright band”belongs to the melted zone and is a vertical section of the plane crystal,The width of the“bright band”equals the height of the plane crystal,which decreases with the increase of laser beam scanning rate and the decrease of laser power.This has been explained in terms of constitutional supercooling G/R.
基金supported by the National High-Level Talent Fund and the National Natural Science Foundation of China(Nos.22072118,22372138,22388102,21973013,and 22373017)support from State Key Laboratory of Physical Chemistry of Solid Surfaces of Xiamen University+3 种基金supported by Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)(No.HRTP-[2022]-3)the Fundamental Research Funds for the Central Universities(No.20720220008)The computations were performed at the Hefei Advanced Computing Center and Supercomputing Center of Fujian.The XAS experiments used resources at the 8-ID beamline of the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory(No.DE-SC0012704)J.Y.H.thank the National Natural Science Foundation of China(Nos.U20A20336 and 21935009)and the Natural Science Foundation of Hebei Province(No.B2020203037).
文摘The local structure of the metal single-atom site is closely related to the catalytic activity of metal single-atom catalysts(SACs).However,constructing SACs with homogeneous metal active sites is a challenge due to the surface heterogeneity of the conventional support.Herein,we prepared two Rh1/CeO_(2)SACs(0.5Rh1/r-CeO_(2)and 0.5Rh1/c-CeO_(2),respectively)using two shaped CeO_(2)(rod and cube)exposing different facets,i.e.,CeO_(2)(111)and CeO_(2)(100).In CO oxidation reaction,the T100 of 0.5Rh1/r-CeO_(2)SACs is 120°C,while the T100 of 0.5Rh1/c-CeO_(2)SACs is as high as 200°C.Via in-situ CO diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),we found that the proximity between OH group and Rh single atom on the plane surface plays an important role in the catalytic activity of Rh1/CeO_(2)SAC system in CO oxidation.The Rh single atom trapped at the CeO_(2)(111)crystal surface forms the Rh1(OH)adjacent species,which is not found on the CeO_(2)(100)crystal surface at room temperature.Furthermore,during CO oxidation,the OH group far from Rh single atom on the 0.5Rh1/c-CeO_(2)disappears and forms Rh1(OH)adjacent species when the temperature is above 150°C.The formation of Rh1(OH)adjacentCO intermediate in the reaction is pivotal for the excellent catalytic activity,which explains the difference in the catalytic activity of Rh single atoms on two different CeO_(2)planes.The formed Rh1(OH)adjacent-O-Ce structure exhibits good stability in the reducing atmosphere,maintaining the Rh atomic dispersion after CO oxidation even when pre-reduced at high temperature of 500°C.Density functional theory(DFT)calculations validate the unique activity and reaction path of the intermediate Rh1(OH)adjacentCO species formed.This work demonstrates that the proximity between metal single atom and hydroxyl can determine the formation of active intermediates to affect the catalytic performances in catalysis.
基金This work was supported by National Natural Science Foundation of China(NSFC)(No.90606006)the State Key Project of Fundamental Research for Nanoscience and Nanotechnology(No.2006CB932300)the Key Grant Project of the Chinese Ministry of Education(No.306020)。
文摘The catalytic activity of crystallites depends mainly upon the arrangement of surface atoms,the number of dangling bonds,and defect site distribution on different crystal planes.Here,we report the shape-controlled synthesis of CuCl crystallites,including tetrahedra,face-centered-etched tetrahedra,tripod dendrites,and tetrapods.These different morphologies of CuCl crystallites expose different proportions of{111}and{110}crystal planes,and materials with a preponderance of{111}crystal planes have better catalytic activity in aniline coupling than those with more{110}planes.
基金the Key Programs of the Chinese Academy of Sciences(No.KGZD-EW-304-2)the National Basic Research Program of China(No.2012CB215302)+1 种基金Science and Technological Fund of Anhui Province for Outstanding Youth(1508085J01)the National Key Technologies R&D Program(2015BAD15B06).
文摘Cellulose polymerization degree and crystal plane changing are both considered to affect acid hydrolysis,however,it is uncertain to identify which one is more important.In this study,the filter paper was treated with dilute hydrochloric acid to investigate the cellulose polymerization degree changing,and cotton linter was treated with NaOH for the purpose of changing its crystal plane.Both the treated and untreated samples were hydrolyzed under the condition of 1.0 wt%dilute hydrochloric acid with solid-liquid ratio 1:40 at 140℃for 30 min to compare the hydrolysis effects.It was found that the glucose yield increased from 9.5%to 19.7%when treated with 15%NaOH at 50℃for 30 min,and new crystal planes(1-10)(1-20)appeared after alkali treatment.According to the experimental results,it is concluded that crystal plane plays a vital role in cellulose acid hydrolysis.
基金Financial support provided by the National Natural Science Foundation of China(Grant No.U2067216)NSAF(Grant No.U2130109)is greatly appreciated.
文摘The rapid development of the aerospace and nuclear industries is accompanied by increased exposure to high-energy ionising radiation.Thus,the performance of radiation shielding materials needs to be improved to extend the service life of detectors and ensure the safety of personnel.The development of novel lightweight materials with high electron density has therefore become urgent to alleviate radiation risks.In this work,new MAPbI_(3)/epoxy(CH 3NH 3PbI 3/epoxy)composites were prepared via a crystal plane engineering strategy.These composites delivered excellent radiation shielding performance against 59.5 keV gamma rays.A high linear attenuation coefficient(1.887 cm−1)and mass attenuation coefficient(1.352 cm2 g−1)were achieved for a representative MAPbI_(3)/epoxy composite,which was 10 times higher than that of the epoxy.Theoretical calculations indicate that the electron density of MAPbI_(3)/epoxy composites significantly increases when the content ratio of the(110)plane in MAPbI_(3) increases.As a result,the chances of collision between the incident gamma rays and electrons in the MAPbI_(3)/epoxy composites were enhanced.The present work provides a novel strategy for designing and developing high-efficiency radiation shielding materials.
基金Financial support by Natural Science Foundation of China (NSFC) (Nos. 21325626, 21176179, U1510203)the Program for New Century Excellent Talents in University (No. NCET-13-0411)the Program of Introducing Talents of Discipline to Universities (No. B06006)
文摘The mechanism of dimethyl carbonate(DMC) formation from CO2 and methanol is investigated using three well-shaped CeO2 catalysts, nanorod, nanocube and octahedron, which are packed with different crystal planes. In situ Fourier Transform Infrared Spectroscopy(FTIR) is employed to probe each reaction step in the DMC synthesis. The number of –OH groups and the species of CO2 adsorptions on ceria surface have significant influence on the activity of ceria with different morphologies. Rod-ceria has favorable catalytic activity because of the large amount of –OH groups and the formation of bidentate carbonate species.