With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are ...With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are excellent substitutes for ionic liquids because of their good biocompatibility,low cost,and easy preparation,except for good conductivity.In this work,we synthesized a reactive quaternary ammonium monomer(3-acrylamidopropyl)octadecyldimethyl ammonium bromide with a hydrophobic chain of 18 carbons via the quaternization of 1-bromooctadecane and N-dimethylaminopropyl acrylamide at first,then we mixed quaternary ammonium with choline chloride,acrylic acid and glycerol to obtain a hydrophobic deep eutectic solvent,and initialized polymerization in UV light of 365 nm to obtain the ionic conductive eutectogel based on polyacrylamide copolymer with long hydrophobic chain.The obtained eutectogel exibits good stretchability(1200%),Young's modulus(0.185 MPa),toughness(4.2 MJ/m^(3)),conductivity(0.315 S/m).The eutectogel also shows desireable moisture resistance with the maximum water absorption of 11.7 wt%after one week at 25℃ and 60% humidity,while the water absorption of eutectogel without hydrophobic long chains is 24.0 wt%.The introduction of long-chain hydrophobic groups not only improves the mechanical strength of the gels,but also significantly improves moisture resistance of the eutectogel.This work provides a simpler and more effective method for the preparation of ionic conductive eutectogels,which can further provide a reference for the applications of ionic conductive eutectogels in the field of flexible electronic devices.展开更多
Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregat...Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains.Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water.It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm^(2).The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope(HRTEM),photoluminescence(PL)and X-ray diffraction(XRD).Remarkably,an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal(i.e.,a maximum rate of 5915μmol h^(-1) m^(-2))is observed in pure water triggered by ultrasound in dark,which is over 100 times higher than that of its powder counterpart(i.e.,52.54μmol h^(-1) m^(-2)).The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet,thickness and conductivity.Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential,revealed by the finite element method(FEM)simulation.The density functional theory(DFT)calculations are employed to investigate the piezocatalytic hydrogen evolution process,indicating a strong H_(2)O adsorption and a low energy barrier for both H_(2)O dissociation and H2 generation on the stressed Znterminated(0001)ZnO surface.展开更多
Entropy engineering has emerged as an effective strategy for improving the figure-of-merit zT by decelerating the phonon transport while maintaining good electrical transport properties of thermoelectric materials.Her...Entropy engineering has emerged as an effective strategy for improving the figure-of-merit zT by decelerating the phonon transport while maintaining good electrical transport properties of thermoelectric materials.Herein,a high average zT of 1.54 and a maximum zT of 2.1 are achieved in the mid-entropy GeTe constructed by Ag,Sb,and Pb alloying.At room temperature,the mid-entropy GeTe tends to be a cubic structure.And the power factor is improved from 7.7μW·cm^(-1)·K^(-2) to 16.2μW·cm·cm^(-1)·K^(-2) due to the large increase in effective mass and the optimized carrier concentration.The increasing disorder created by heavy and off-centering Ag,Sb,and Pb atoms induces strong mass/strain fluctuations and phonon scattering to decelerate the phonon transport in GeTe.A low lattice thermal conductivity is obtained in the medium-entropy GeTe-based material.Moreover,a GeTe-based thermoelectric cooler is fabricated with the cooling temperature difference of 66.6 K with the hot end fixed at 363 K.This work reveals the effectiveness of entropy engineering in improving the average zT in GeTe and shows potential application of GeTe as a thermoelectric cooler.展开更多
Various strategies for thermoelectric material optimization have been widely studied and used for promoting electrical transport and suppressing thermal transport.As a nontraditional method,pressure has shown great po...Various strategies for thermoelectric material optimization have been widely studied and used for promoting electrical transport and suppressing thermal transport.As a nontraditional method,pressure has shown great potential,as it has been applied to obtain a high thermoelectric figure of merit,but the microscopic mechanisms involved have yet to be fully explored.In this study,we focus on r-GeTe,a lowtemperature phase of GeTe,and investigate the pressure effects on the electronic structure,electrical transport properties and anharmonic lattice dynamics based on density functional theory(DFT),the Boltzmann transport equations(BTEs)and perturbation theory.Electronic relaxation times are obtained based on the electron-phonon interaction and the constant relaxation time approximation.The corresponding electrical transport properties are compared with those obtained from previous experiments.Hydrostatic pressure is shown to increase valley degeneracy,decrease the band effective mass and enhance the electrical transport property.At the same time,the increase in the low-frequency phonon lifetime and phonon group velocity leads to an increase in lattice thermal conductivity under pressure.This study provides insight into r-GeTe under hydrostatic pressure and paves the way for a high-pressure strategy to optimize transport properties.展开更多
In the 21^(st)century,the rapid development of human society has made people’s demand for green energy more and more urgent.The high-energy-density hydrogen energy obtained by fully splitting water is not only enviro...In the 21^(st)century,the rapid development of human society has made people’s demand for green energy more and more urgent.The high-energy-density hydrogen energy obtained by fully splitting water is not only environmentally friendly,but also is expected to solve the problems caused by the intermittent nature of new energy.However,the slow kinetics and large overpotential of the oxygen evolution reaction(OER)limit its application.The introduction of Te element is expected to bring new breakthroughs.With the least electronegativity among the chalcogens,the Te element has many special properties,such as multivalent states,strong covalentity,and high electrical conductivity,which make it a promising candidate in electrocatalytic OER.In this review,we introduce the peculiarities of Te element,summarize Te doping and the extraordinary performance of its compounds in OER,with emphasis on the scientific mechanism behind Te element promoting the OER kinetic process.Finally,challenges and development prospects of the applications of Te element in OER are presented.展开更多
Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-e...Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.%±0.23 at.%from palladium–silicon liquid droplets.In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon.Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake,exhibiting a great potential application for hydrogen separation.Our results provide insight into the formation of amorphous metal at nanoscale.展开更多
When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature,the diffusion of carbon on or in catalysts dramatically influences the catalytic performance.Acquiring inform...When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature,the diffusion of carbon on or in catalysts dramatically influences the catalytic performance.Acquiring information on the carbon-diffusioninvolved evolution of catalysts at the atomic level is crucial for understanding the reaction mechanism yet also challenging.For the chemical vapor deposition process of single-walled carbon nanotubes(SWCNTs),we recorded in situ the catalyst state(solid and molten)composition as well as near-surface structural and chemical evolution at the cobalt catalyst-tube interface with carbon permeation using aberration-corrected environmental transmission electron microscopy and synchrotron X-ray absorption spectroscopy.The nucleation of SWCNTs was linked with an alternating dissolving and precipitating cycle of carbon in catalysts close to the nucleation site.Understanding the dynamics of carbon atoms in catalysts brings deeper insight into the growth mechanism of SWCNTs and facilitates inferring mechanisms of other reactions.The methodologies developed here will find broad applications in studying catalytic and other processes.展开更多
基金This work was supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2016ZX05016 and No.2016ZX05046).
文摘With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are excellent substitutes for ionic liquids because of their good biocompatibility,low cost,and easy preparation,except for good conductivity.In this work,we synthesized a reactive quaternary ammonium monomer(3-acrylamidopropyl)octadecyldimethyl ammonium bromide with a hydrophobic chain of 18 carbons via the quaternization of 1-bromooctadecane and N-dimethylaminopropyl acrylamide at first,then we mixed quaternary ammonium with choline chloride,acrylic acid and glycerol to obtain a hydrophobic deep eutectic solvent,and initialized polymerization in UV light of 365 nm to obtain the ionic conductive eutectogel based on polyacrylamide copolymer with long hydrophobic chain.The obtained eutectogel exibits good stretchability(1200%),Young's modulus(0.185 MPa),toughness(4.2 MJ/m^(3)),conductivity(0.315 S/m).The eutectogel also shows desireable moisture resistance with the maximum water absorption of 11.7 wt%after one week at 25℃ and 60% humidity,while the water absorption of eutectogel without hydrophobic long chains is 24.0 wt%.The introduction of long-chain hydrophobic groups not only improves the mechanical strength of the gels,but also significantly improves moisture resistance of the eutectogel.This work provides a simpler and more effective method for the preparation of ionic conductive eutectogels,which can further provide a reference for the applications of ionic conductive eutectogels in the field of flexible electronic devices.
基金the financial support from the National Natural Science Foundation of China(No.21905317)the financial support from the National Natural Science Foundation of China(No.91833301)the Youth Talent Promotion Project from China Association for Science and Technology。
文摘Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains.Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water.It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm^(2).The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope(HRTEM),photoluminescence(PL)and X-ray diffraction(XRD).Remarkably,an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal(i.e.,a maximum rate of 5915μmol h^(-1) m^(-2))is observed in pure water triggered by ultrasound in dark,which is over 100 times higher than that of its powder counterpart(i.e.,52.54μmol h^(-1) m^(-2)).The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet,thickness and conductivity.Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential,revealed by the finite element method(FEM)simulation.The density functional theory(DFT)calculations are employed to investigate the piezocatalytic hydrogen evolution process,indicating a strong H_(2)O adsorption and a low energy barrier for both H_(2)O dissociation and H2 generation on the stressed Znterminated(0001)ZnO surface.
基金This work is supported by the National Natural Science Foundation of China(Grant No.52222209,11934007,and 52302262)the Science and Technology Innovation Committee Foundation of Shenzhen(Grant No.JCYJ20220530165000001)+2 种基金the Young Elite Scientists Sponsorship Program by CAST(Grant No.2021QNRC001)the Outstanding Talents Training Fund in Shenzhen(202108)the Natural Science Foundation of Sichuan(Grant No.2023NSFSC0953).
文摘Entropy engineering has emerged as an effective strategy for improving the figure-of-merit zT by decelerating the phonon transport while maintaining good electrical transport properties of thermoelectric materials.Herein,a high average zT of 1.54 and a maximum zT of 2.1 are achieved in the mid-entropy GeTe constructed by Ag,Sb,and Pb alloying.At room temperature,the mid-entropy GeTe tends to be a cubic structure.And the power factor is improved from 7.7μW·cm^(-1)·K^(-2) to 16.2μW·cm·cm^(-1)·K^(-2) due to the large increase in effective mass and the optimized carrier concentration.The increasing disorder created by heavy and off-centering Ag,Sb,and Pb atoms induces strong mass/strain fluctuations and phonon scattering to decelerate the phonon transport in GeTe.A low lattice thermal conductivity is obtained in the medium-entropy GeTe-based material.Moreover,a GeTe-based thermoelectric cooler is fabricated with the cooling temperature difference of 66.6 K with the hot end fixed at 363 K.This work reveals the effectiveness of entropy engineering in improving the average zT in GeTe and shows potential application of GeTe as a thermoelectric cooler.
基金supported by the Research Grants Council of Hong Kong(17201019)the National Natural Science Foundation of China(11934007,11874194and 11874313)+3 种基金the Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(NO.2018B030322001)the Science and Technology Innovation Committee Foundation of Shenzhen(KQTD2016022619565991)the Zhejiang Provincial Natural Science Foundation(LR19A040001)SL acknowledges the support from the startup fund of Nanjing University of Posts and Telecommunications(NY220096).
文摘Various strategies for thermoelectric material optimization have been widely studied and used for promoting electrical transport and suppressing thermal transport.As a nontraditional method,pressure has shown great potential,as it has been applied to obtain a high thermoelectric figure of merit,but the microscopic mechanisms involved have yet to be fully explored.In this study,we focus on r-GeTe,a lowtemperature phase of GeTe,and investigate the pressure effects on the electronic structure,electrical transport properties and anharmonic lattice dynamics based on density functional theory(DFT),the Boltzmann transport equations(BTEs)and perturbation theory.Electronic relaxation times are obtained based on the electron-phonon interaction and the constant relaxation time approximation.The corresponding electrical transport properties are compared with those obtained from previous experiments.Hydrostatic pressure is shown to increase valley degeneracy,decrease the band effective mass and enhance the electrical transport property.At the same time,the increase in the low-frequency phonon lifetime and phonon group velocity leads to an increase in lattice thermal conductivity under pressure.This study provides insight into r-GeTe under hydrostatic pressure and paves the way for a high-pressure strategy to optimize transport properties.
基金support from the National Natural Science Foundation of China(No.21905317)the Young Elite Scientists Sponsorship Program by CAST(No.2019QNRC001).
文摘In the 21^(st)century,the rapid development of human society has made people’s demand for green energy more and more urgent.The high-energy-density hydrogen energy obtained by fully splitting water is not only environmentally friendly,but also is expected to solve the problems caused by the intermittent nature of new energy.However,the slow kinetics and large overpotential of the oxygen evolution reaction(OER)limit its application.The introduction of Te element is expected to bring new breakthroughs.With the least electronegativity among the chalcogens,the Te element has many special properties,such as multivalent states,strong covalentity,and high electrical conductivity,which make it a promising candidate in electrocatalytic OER.In this review,we introduce the peculiarities of Te element,summarize Te doping and the extraordinary performance of its compounds in OER,with emphasis on the scientific mechanism behind Te element promoting the OER kinetic process.Finally,challenges and development prospects of the applications of Te element in OER are presented.
基金supported by the National Natural Science Foundation of China(Nos.51602143,51702150,11874194,11774142,and 11874194)the Science and Technology Innovation Committee Foundation of Shenzhen(Nos.KQTD2016022619565991,JCYJ20200109141205978,and ZDSYS20141118160434515)+1 种基金the Natural Science Foundation of Guangdong Province(No.2015A030308001)the Leading Talents of Guangdong Province Program(No.00201517)。
文摘Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.%±0.23 at.%from palladium–silicon liquid droplets.In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon.Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake,exhibiting a great potential application for hydrogen separation.Our results provide insight into the formation of amorphous metal at nanoscale.
基金supported by National Key Research and Development Program of China(nos.2016YFA0201904 and 2018YFA0703700)National Natural Science Foundation of China(NSFC)(nos.21631002,12034002,and 51971025)+7 种基金Beijing National Laboratory for Molecular Sciences(no.BNLMS-CXTD202001)Shenzhen Basic Research Project(no.JCYJ20170817113121505)Shenzhen KQTD Project(no.KQTD20180411143400981)Fundamental Research Funds for the Central Universities(no.FRFBD-18-004A)J.H.acknowledges the Science and Technology Innovation Committee Foundation of Shenzhen(nos.KQTD2016022619565991 and ZDSYS20141118160434515)F.Y.was supported in part by NSFC(no.52002165)Beijing National Laboratory for Molecular Science(no.BNLMS202013)Guangdong Provincial Natural Science Foundation,Innovation Project for Guangdong Provincial Department of Education(no.2019KTSCX155).
文摘When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature,the diffusion of carbon on or in catalysts dramatically influences the catalytic performance.Acquiring information on the carbon-diffusioninvolved evolution of catalysts at the atomic level is crucial for understanding the reaction mechanism yet also challenging.For the chemical vapor deposition process of single-walled carbon nanotubes(SWCNTs),we recorded in situ the catalyst state(solid and molten)composition as well as near-surface structural and chemical evolution at the cobalt catalyst-tube interface with carbon permeation using aberration-corrected environmental transmission electron microscopy and synchrotron X-ray absorption spectroscopy.The nucleation of SWCNTs was linked with an alternating dissolving and precipitating cycle of carbon in catalysts close to the nucleation site.Understanding the dynamics of carbon atoms in catalysts brings deeper insight into the growth mechanism of SWCNTs and facilitates inferring mechanisms of other reactions.The methodologies developed here will find broad applications in studying catalytic and other processes.
