Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann tran...Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann transport equation solution and the two-temperature model were employed to investigate the efficacy of targeted phonon excitation applied to hexagonal boron nitride(hBN).The results indicate significant modifications to hBN's thermal conductivity,achieving increases of up to 30.1%as well as decreases of up to 59.8%.These findings validate the reliability of the strategy,expand its scope of applicability,and establish it as a powerful tool for tailoring thermal properties across a wider range of fields.展开更多
The implementation of metal organic frameworks(MOFs) as the co-catalysts in hybrid photocatalytic systems puts requirements on both their charge-carrying capability and solvent stability. In the current study, in orde...The implementation of metal organic frameworks(MOFs) as the co-catalysts in hybrid photocatalytic systems puts requirements on both their charge-carrying capability and solvent stability. In the current study, in order to simultaneously promote the electrical conductivity and water stability of ZIF-67, an insitu monomer trapping strategy is deployed to synthesize polypyrrole(PPy)-reinforced ZIF-67 ensembles.Through coordination modulation, the incremental addition of pyrrole monomers enables to alter the crystal morphology of ZIF-67 from rhombic dodecahedra to truncated rhombic dodecahedra, and further to cubes. Upon polymerization, the resulted composite, in comparison to ZIF-67, demonstrates a billionfold conductivity enhancement, much improved chemical stability in pronated solvents, as well as largely retained specific surface area and porosity, enabling it functioning as an outstanding co-catalyst for catalyzing robust photocatalytic CO_(2) reduction. Furthermore, a PPy-mediated electron harvest and relay mechanism is proposed for rationalizing the enhanced photocatalytic performance.展开更多
Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high co...Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.展开更多
SnSe_(2) single crystals,as novel n-type plastic thermoelectric materials,present advantages such as envi-ronmental sustainability and cost-effectiveness.Single crystals of SnSe_(2)+x%PbBr_(2)(x=0,0.5,1,2,and 3)with l...SnSe_(2) single crystals,as novel n-type plastic thermoelectric materials,present advantages such as envi-ronmental sustainability and cost-effectiveness.Single crystals of SnSe_(2)+x%PbBr_(2)(x=0,0.5,1,2,and 3)with large size and high quality were successfully synthesized via the Bridgman method.The significant enhancement in power factor and effective suppression of lattice thermal conductivity can be achieved through PbBr_(2) doping,verifying a synergistic optimization of electrical and thermal transport properties.Specifically,Br atoms are effectively incorporated into the Se sites to manipulate the carrier concentra-tion and optimize the power factor,while simultaneously inducing a strong phonon softening effect by introducing Pb atoms at the Sn sites,which leads to a reduced phonon group velocity and a suppres-sion of lattice thermal conductivity.Consequently,SnSe_(2)+2%PbBr_(2) single-crystal sample achieves a peak figure of merit zT of~0.76 and an average zT of~0.51,giving rise to corresponding improvements of~533% and~538%,respectively,compared to the pristine SnSe_(2) sample,thereby outperforming most of the previously reported SnSe_(2)-based materials.This work provides a viable approach for promoting the thermoelectric performance of SnSe^(2)-based single crystals across a broad temperature range and supports the advancement of plastic thermoelectric materials.展开更多
The service module of Chang’e 5-T1 has been conducting an in-orbit demonstration for the Chang’e-5 mission since it was left in space.The service module departed Earth-Moon L2 point finishing its extended L2 point f...The service module of Chang’e 5-T1 has been conducting an in-orbit demonstration for the Chang’e-5 mission since it was left in space.The service module departed Earth-Moon L2 point finishing its extended L2 point fly-by tests on January 4and entered a 127-minute circumlunar round orbit on January 13 with an altitude of 200km and inclined angle of 43.7degrees after three braking actions at perilune on January 11,12 and 13.During the L2 point fly-by,the cameras on-展开更多
Two-dimensional(2D)BiOBr has garnered significant interest due to its exceptional optoelectronic properties.Currently,reported 2D BiOBr primarily exhibits n-type conductivity.However,in the field of optoelectronics,pa...Two-dimensional(2D)BiOBr has garnered significant interest due to its exceptional optoelectronic properties.Currently,reported 2D BiOBr primarily exhibits n-type conductivity.However,in the field of optoelectronics,particularly within complementary metal oxide semiconductor(CMOS)integrated circuits,there is an urgent demand for high-quality p-type 2D semiconductors.In this study,we present the synthesis of high-quality,large-scale p-type 2D BiOBr crystals using chemical potential modulation chemical vapor deposition(CPMCVD).Notably,the conduction polarity of 2D BiOBr can be precisely controlled by modulating the oxygen chemical potential during the synthesis process.Density functional theory(DFT)calculations indicate that high oxygen chemical potential promotes the formation of bismuth vacancies in 2D BiOBr,resulting in p-type conductivity.Conversely,as the oxygen chemical potential decreases,oxygen vacancies become the predominant defects,leading to n-type BiOBr.Furthermore,both p-type and n-type high-performance field-effect transistors(FETs)based on 2D BiOBr have been fabricated.The p-type FETs exhibit a superior hole mobility of 26.28 cm^(2)V^(−1)s^(−1)and on/off ratio exceeding 104.The n-type FETs demonstrate an electron mobility of 59.59 cm^(2)V^(−1)s^(−1),surpassing those reported for most n-type FETs.This breakthrough in the precise control of conduction polarity in 2D BiOBr using CPMCVD not only represents a significant milestone but also greatly expands its potential applications in advancing CMOS technology.展开更多
A new lateral insulated-gate bipolar transistor（LIGBT） with a SiO_2 shielded layer anode on SOI substrate is proposed and discussed.Compared to the conventional LIGBT,the proposed device offers an enhanced conductiv...A new lateral insulated-gate bipolar transistor（LIGBT） with a SiO_2 shielded layer anode on SOI substrate is proposed and discussed.Compared to the conventional LIGBT,the proposed device offers an enhanced conductivity modulation effect due to the SiO_2 shielded layer anode structure which can be formed by SIMOX technology.Simulation results show that,for the proposed LIGBT,during the conducting state,the electron-hole plasma concentrations in the n-drift region are several times larger than those of the conventional LIGBT;the conducting current is up to 37% larger than that of the conventional one.The enhanced conductivity modulation effect by SiO_2 shielded layer anode does not sacrifice other characteristics of the device,such as breakdown and switching,but is compatible with other optimized technologies.展开更多
The development of core-shell nanoclusters with controllable composition is of utmost importance as the material properties depend on their constituent elements.However,precisely tuning their compositions at the atomi...The development of core-shell nanoclusters with controllable composition is of utmost importance as the material properties depend on their constituent elements.However,precisely tuning their compositions at the atomic scale is not easily achieved because of the difficulty of using limited macroscopic synthetic methods for atomic-level modulation.In this work,we report an interesting example of precisely regulating the core composition of an inorganic core-shell-type cobalt polyoxoniobate[Co_(26)Nb_(36)O_(140)]^(32−)by controlling reaction conditions,in which the inner Co-core composition could be tune while retaining the outer Nb-shell composition of resulting product,leading to a series of isostructural species with a general formula of{Co_(26-n)Nb_(36+n)O_(140)}(n=0–2).These rare species not only can display good powder and single-crystal proton conductivities,but also might provide helpful and atomic-level insights into the syntheses,structures and composition modifications of inorganic amorphous core-shell heterometal oxide nanoparticles.展开更多
基金supported by the National Key Research and Development Project of China(Grant No.2018YFE0127800)。
文摘Recent advancements in thermal conductivity modulating strategies have shown promising enhancements to the thermal management capabilities of two-dimensional materials.In this article,both the iterative Boltzmann transport equation solution and the two-temperature model were employed to investigate the efficacy of targeted phonon excitation applied to hexagonal boron nitride(hBN).The results indicate significant modifications to hBN's thermal conductivity,achieving increases of up to 30.1%as well as decreases of up to 59.8%.These findings validate the reliability of the strategy,expand its scope of applicability,and establish it as a powerful tool for tailoring thermal properties across a wider range of fields.
基金supported by the National Natural Science Foundation of China (Nos. 22072101, 22075193, 51911540473)the Natural Science Research Project of Jiangsu Higher Education Institutions of China (18KJA480004)+2 种基金the Key Technology Initiative of Suzhou Municipal Science and Technology Bureau (SYG201934) Six Talent Peaks Project in Jiangsu Province (TD-XCL-006)the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutionsthe support from the Honorary Professor Program of Jiangsu Province。
文摘The implementation of metal organic frameworks(MOFs) as the co-catalysts in hybrid photocatalytic systems puts requirements on both their charge-carrying capability and solvent stability. In the current study, in order to simultaneously promote the electrical conductivity and water stability of ZIF-67, an insitu monomer trapping strategy is deployed to synthesize polypyrrole(PPy)-reinforced ZIF-67 ensembles.Through coordination modulation, the incremental addition of pyrrole monomers enables to alter the crystal morphology of ZIF-67 from rhombic dodecahedra to truncated rhombic dodecahedra, and further to cubes. Upon polymerization, the resulted composite, in comparison to ZIF-67, demonstrates a billionfold conductivity enhancement, much improved chemical stability in pronated solvents, as well as largely retained specific surface area and porosity, enabling it functioning as an outstanding co-catalyst for catalyzing robust photocatalytic CO_(2) reduction. Furthermore, a PPy-mediated electron harvest and relay mechanism is proposed for rationalizing the enhanced photocatalytic performance.
基金funded by the National Natural Science Foundation of China(No.52202446)the Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)+2 种基金the Young Elite Scientists Sponsorship Program by BAST(No.BYESS2023050)the Beijing Association for Science and Technology’s Golden-Bridge Seed Funding Program(No.ZZ22042)the Fundamental Research Funds for the Central Universities of China。
文摘Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52125103,52371212,52071041,12204080,12374002)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Nos.KJQN202400604,KJQN202200623,KJZD-K202100602)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.2024IAIS-ZX002,2023CDJKYJH006)the Natural Science Foundation of Chongqing(No.CSTB2022NSCQ-MSX0382).
文摘SnSe_(2) single crystals,as novel n-type plastic thermoelectric materials,present advantages such as envi-ronmental sustainability and cost-effectiveness.Single crystals of SnSe_(2)+x%PbBr_(2)(x=0,0.5,1,2,and 3)with large size and high quality were successfully synthesized via the Bridgman method.The significant enhancement in power factor and effective suppression of lattice thermal conductivity can be achieved through PbBr_(2) doping,verifying a synergistic optimization of electrical and thermal transport properties.Specifically,Br atoms are effectively incorporated into the Se sites to manipulate the carrier concentra-tion and optimize the power factor,while simultaneously inducing a strong phonon softening effect by introducing Pb atoms at the Sn sites,which leads to a reduced phonon group velocity and a suppres-sion of lattice thermal conductivity.Consequently,SnSe_(2)+2%PbBr_(2) single-crystal sample achieves a peak figure of merit zT of~0.76 and an average zT of~0.51,giving rise to corresponding improvements of~533% and~538%,respectively,compared to the pristine SnSe_(2) sample,thereby outperforming most of the previously reported SnSe_(2)-based materials.This work provides a viable approach for promoting the thermoelectric performance of SnSe^(2)-based single crystals across a broad temperature range and supports the advancement of plastic thermoelectric materials.
文摘The service module of Chang’e 5-T1 has been conducting an in-orbit demonstration for the Chang’e-5 mission since it was left in space.The service module departed Earth-Moon L2 point finishing its extended L2 point fly-by tests on January 4and entered a 127-minute circumlunar round orbit on January 13 with an altitude of 200km and inclined angle of 43.7degrees after three braking actions at perilune on January 11,12 and 13.During the L2 point fly-by,the cameras on-
基金financially supported by the National Natural Science Foundation of China(62375227)the Natural Science Basic Research Program of Shaanxi(2025JC-QYCX-059)。
文摘Two-dimensional(2D)BiOBr has garnered significant interest due to its exceptional optoelectronic properties.Currently,reported 2D BiOBr primarily exhibits n-type conductivity.However,in the field of optoelectronics,particularly within complementary metal oxide semiconductor(CMOS)integrated circuits,there is an urgent demand for high-quality p-type 2D semiconductors.In this study,we present the synthesis of high-quality,large-scale p-type 2D BiOBr crystals using chemical potential modulation chemical vapor deposition(CPMCVD).Notably,the conduction polarity of 2D BiOBr can be precisely controlled by modulating the oxygen chemical potential during the synthesis process.Density functional theory(DFT)calculations indicate that high oxygen chemical potential promotes the formation of bismuth vacancies in 2D BiOBr,resulting in p-type conductivity.Conversely,as the oxygen chemical potential decreases,oxygen vacancies become the predominant defects,leading to n-type BiOBr.Furthermore,both p-type and n-type high-performance field-effect transistors(FETs)based on 2D BiOBr have been fabricated.The p-type FETs exhibit a superior hole mobility of 26.28 cm^(2)V^(−1)s^(−1)and on/off ratio exceeding 104.The n-type FETs demonstrate an electron mobility of 59.59 cm^(2)V^(−1)s^(−1),surpassing those reported for most n-type FETs.This breakthrough in the precise control of conduction polarity in 2D BiOBr using CPMCVD not only represents a significant milestone but also greatly expands its potential applications in advancing CMOS technology.
基金Project supported by the National Natural Science Foundation of China(Nos.60876053,60806025,60976060).
文摘A new lateral insulated-gate bipolar transistor（LIGBT） with a SiO_2 shielded layer anode on SOI substrate is proposed and discussed.Compared to the conventional LIGBT,the proposed device offers an enhanced conductivity modulation effect due to the SiO_2 shielded layer anode structure which can be formed by SIMOX technology.Simulation results show that,for the proposed LIGBT,during the conducting state,the electron-hole plasma concentrations in the n-drift region are several times larger than those of the conventional LIGBT;the conducting current is up to 37% larger than that of the conventional one.The enhanced conductivity modulation effect by SiO_2 shielded layer anode does not sacrifice other characteristics of the device,such as breakdown and switching,but is compatible with other optimized technologies.
基金the financial support from the National Natural Science Foundation of China(Nos.21971039 and 22171045)and the Key Program of Natural Science Foundation of Fujian Province(No.2021J02007).
文摘The development of core-shell nanoclusters with controllable composition is of utmost importance as the material properties depend on their constituent elements.However,precisely tuning their compositions at the atomic scale is not easily achieved because of the difficulty of using limited macroscopic synthetic methods for atomic-level modulation.In this work,we report an interesting example of precisely regulating the core composition of an inorganic core-shell-type cobalt polyoxoniobate[Co_(26)Nb_(36)O_(140)]^(32−)by controlling reaction conditions,in which the inner Co-core composition could be tune while retaining the outer Nb-shell composition of resulting product,leading to a series of isostructural species with a general formula of{Co_(26-n)Nb_(36+n)O_(140)}(n=0–2).These rare species not only can display good powder and single-crystal proton conductivities,but also might provide helpful and atomic-level insights into the syntheses,structures and composition modifications of inorganic amorphous core-shell heterometal oxide nanoparticles.
