Over the past half-century,significant efforts have been dedicated to the photocatalytic H_(2)production from H_(2)O under UV–visible light irradiation.These endeavors have yielded remarkable results,with efficiency ...Over the past half-century,significant efforts have been dedicated to the photocatalytic H_(2)production from H_(2)O under UV–visible light irradiation.These endeavors have yielded remarkable results,with efficiency levels now approaching near 100%apparent quantum yields,notably utilizing inorganic semiconducting materials such as modified Al-doped SrTiO_(3)photocatalysts.Meanwhile,advancements in organic polymer semiconducting materials,exemplified by g-C_(3)N_(4),have led to substantial improvements in the efficiency of photocatalytic overall water splitting for H_(2)evolution reaction.These improvements,achieved through chemical engineering methods and molecular-level modifications,have resulted in an apparent quantum yield of 69%at 405 nm,accompanied by significant red-shifting of optical absorption to 1400 nm.These developments are presented in chronological order over the past half-century,underscoring the ongoing quest for innovative breakthroughs to enable largescale practical applications of solar hydrogen production.Key considerations in this pursuit include efficiency,stability,cost-effectiveness,and the independent evolution of H_(2)and O_(2).展开更多
Quantum dot(QD)-based infrared photodetector is a promising technology that can implement current monitoring,imaging and optical communication in the infrared region. However, the photodetection performance of self-po...Quantum dot(QD)-based infrared photodetector is a promising technology that can implement current monitoring,imaging and optical communication in the infrared region. However, the photodetection performance of self-powered QD devices is still limited by their unfavorable charge carrier dynamics due to their intrinsically discrete charge carrier transport process. Herein, we strategically constructed semiconducting matrix in QD film to achieve efficient charge transfer and extraction.The p-type semiconducting CuSCN was selected as energy-aligned matrix to match the n-type colloidal PbS QDs that was used as proof-of-concept. Note that the PbS QD/CuSCN matrix not only enables efficient charge carrier separation and transfer at nano-interfaces but also provides continuous charge carrier transport pathways that are different from the hoping process in neat QD film, resulting in improved charge mobility and derived collection efficiency. As a result, the target structure delivers high specific detectivity of 4.38 × 10^(12)Jones and responsivity of 782 mA/W at 808 nm, which is superior than that of the PbS QD-only photodetector(4.66 × 10^(11)Jones and 338 mA/W). This work provides a new structure candidate for efficient colloidal QD based optoelectronic devices.展开更多
In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’d...In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.展开更多
Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a...Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a two-dimensional (2D) tetragonal organic-inorganic ferrimagnetic (FIM) semiconductor of Fe_(14)Se_(16)(peha)_(0.7) (peha = pentaethylenehexamine) with excellent thermal stability and a Curie temperature (T_(C)) higher than 519 K. Magnetic and Mössbauer measurements reveal a long-range magnetic ordering in single crystalline Fe_(14)Se_(16)(peha)0.7 nanosheets. The saturation magnetization and coercivity are 5.9 emu g^(−1) and 0.42 kOe at 5 K, which slightly reduces to 4.6 emu g^(−1) and ∼0 Oe at 300 K. A direct optical bandgap of 2.22 eV is obtained by tuning electronic structure of β-Fe3Se4 host layers through spacer layers consisting of Fe^(3+) and peha. Electrical and Seebeck coefficient data indicate that the n-type semiconductor follows the thermally-activated conduction mechanism (lnρ ∝ T^(−1)) in a range of 130–300 K with an activation energy (Ea) of 62.69 meV. Thermal conductivity is 2.5 W m^(−1) K^(−1) at 300 K, while the Wiedemann–Franz law is strongly violated according to electrical-thermal transport data due to weak incorporation of organic spacer layers and host layers. This study sets the stage for exploiting new room-temperature organic magnetic semiconductor systems for spintronic materials.展开更多
Horizontally aligned semiconducting single-wall carbon nanotube(s-SWCNT)arrays are ideal candidates for next-generation integrated circuits.However,the mainstream synthesis methods for obtaining s-SWCNTs mainly utiliz...Horizontally aligned semiconducting single-wall carbon nanotube(s-SWCNT)arrays are ideal candidates for next-generation integrated circuits.However,the mainstream synthesis methods for obtaining s-SWCNTs mainly utilize the differences in structure and chemical reactivity between them and their metallic counterparts.These differences are too small to greatly improve their purity and reproducibility.Here we report an energy engineering strategy to expand the etching energy barrier difference of SWCNTs with different conductivities.In addition to density functional theory calculations on the energy barrier change,hydrogenation of single-wall carbon nanotubes(SWCNTs)by hydrogen plasma treatment and reversible dehydrogenation by annealing were realized experimentally.The structure-dependent hydrogenation and following selective oxidative etching of SWCNTs were demonstrated.As a result,horizontally aligned s-SWCNT arrays with high purity were obtained.展开更多
Intrinsically stretchable semiconducting polymers play a vital role in the development of wearable electronics,featuring low-cost,large-area and high-density fabrication.Only single-stage dynamic chemical bond has bee...Intrinsically stretchable semiconducting polymers play a vital role in the development of wearable electronics,featuring low-cost,large-area and high-density fabrication.Only single-stage dynamic chemical bond has been widely incorporated into polymer backbones to afford stretchability while multiple dynamic bonds have not been investigated,making a formidable challenge to achieve high stretchability without compromising charge transport properties.Herein,we synthesize a series of stretchable polymer semiconductors incorporating urethane and bipyridine units,which can provide dynamic interconnected polymer network by combination of hydrogen bonds with metal coordination,simultaneously obtaining excellent stretchability and carrier mobilities.Compared with single-stage hydrogen bonds,multiple dynamic chemical bonds constructed by 10% hydrogen bonds and 0.25 equiv.metal coordination endowed the polymer semiconductors with an 58% enhancement in carrier mobility and a two-fold increase in crack-onset strain.Notably,the polymer exhibited stable carrier mobilities parallel to the stretching direction,with 91% of initial values even under 150% strain,which is the unprecedented value for intrinsically stretchable semiconducting polymers without blending of elastomers.Therefore,the introduction of multiple dynamic bonds provides an effective and promising approach for intrinsically stretchable and high-performance polymer semiconductor.展开更多
SrRuO_(3)is a canonical itinerant ferromagnet,yet its properties in the extreme two-dimensional limit on a(111)crystal plane remain largely unexplored.Here,we demonstrate a complete transformation of its ground state ...SrRuO_(3)is a canonical itinerant ferromagnet,yet its properties in the extreme two-dimensional limit on a(111)crystal plane remain largely unexplored.Here,we demonstrate a complete transformation of its ground state driven by dimensional reduction.As the thickness of(111)-oriented SrRuO_(3)films is reduced to a few unit cells,the system transitions from a metallic ferromagnet to a semiconducting antiferromagnet.This emergent antiferromagnetism is evidenced by a vanishing magnetic remanence and most strikingly,by the appearance of an unconventional twelve-fold anisotropic magnetoresistance.First-principles calculations confirm that an A-type antiferromagnetic order is the stable ground state in the ultrathin limit.Our findings establish(111)dimensional engineering as a powerful route to manipulate correlated electron states and uncover novel functionalities for antiferromagnetic spintronics.展开更多
Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless chara...Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless character of graphene-like silicene,a recently reported silicon allotropy with a honeycomb-kagome lattice is a semiconductor.Here,based on first-principles calculations,we set out to investigate the thermoelectric transport performance of this semiconducting silicene.Since the mean free path of a large number of phonons in this structure is less than the Ioffe–Regel limit,we employ the quantum Boltzmann transport equation(BTE)method to obtain an accurate prediction of lattice thermal conductivity.Importantly,we unexpectedly find much lower lattice thermal conductivity compared to that of graphene-like silicene,i.e.,about 1.73W·m^(−1)·K^(−1)at room temperature.Meanwhile,the electronic transport coefficient is calculated within the strictly electron–phonon coupling calculation and a full solution of the electron BTE.The optimal thermoelectric figure of merit ZT reaches 3.2 in N-doped silicene at 700K with an optimized low carrier concentration of 8×10^(10)cm^(−2),which is a recorded value among two-dimensional materials.Our work paved the way for applications of silicon-based two-dimensional materials in on-chip thermoelectric cooling and clean energy.展开更多
Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.B...Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.展开更多
Real-time detection of acetic acid vapor is of concern for ensuring environmental and personal safety.However,acetic acid gas sensors,particularly those based on Bi_(2)O_(3),often fail to meet practical performance re...Real-time detection of acetic acid vapor is of concern for ensuring environmental and personal safety.However,acetic acid gas sensors,particularly those based on Bi_(2)O_(3),often fail to meet practical performance requirements owing to their slow response characteristics and high operating temperature.To enhance sensing performance,highly permeable Bi_(2)O_(3)microspheres decorated by Pt-nanoparticles are rationally synthesized by a facile template method.Among the fabricated sensors,the one based on 3 wt%Pt-decorated Bi_(2)O_(3)demonstrated excellent sensing performance.Specifically,the sensor displayed high selectivity for acetic acid,rapid response and recovery times(22.5 and 9 s,respectively),strong resistance to interference,and good long-term stability at a low operating temperature(150℃).Notably,the sensor exhibited an exceptionally high response of 126 to 100 ppm acetic acid—the highest reported value for Bi_(2)O_(3)-based sensors tested at a relatively low operating temperature in recent years.These results demonstrate that Pt-decorated Bi_(2)O_(3)holds strong potential for use in high-performance acetic acid sensors.展开更多
This work presents the electronic behavior of Ti and TiN thin films when exposed to electrolytes with pH levels of 2,7 and 13 for 90 days.Staircase potentio-electrochemical impedance spectroscopy tests were performed ...This work presents the electronic behavior of Ti and TiN thin films when exposed to electrolytes with pH levels of 2,7 and 13 for 90 days.Staircase potentio-electrochemical impedance spectroscopy tests were performed on the 100-nm Ti and TiN monolithic films,and MottSchottky analysis of these tests was used to determine the films’ semiconductive behavior and changes in the donor/acceptor density.In addition,the flat-band potential of each film’s surface oxide was also characterized.No attempt was made to control oxide formation,and therefore,these tests reflected the native surfaces of these films.While the TiN films exhibited n-type semiconductivity in all electrolytes,the Ti films only showed n-type behavior in the acidic(pH=2) and neutral(pH=7) electrolytes.The semiconductivity of the Ti films transitioned to p-type during exposure to the basic electrolyte(pH=13) after reaching 60 days.Furthermore,there was a significant increase in the donor densities for both Ti and TiN films when immersed in the basic electrolyte relative to the acidic and neutral electrolytes.展开更多
A novel conjugated polymer which shows sendconductivity at T < 260K and T >286K and metallic conductivity at 260K < T< 286K was syllthesized by reaction of 2, 3, 5, 6-tetracyano1, 4-dithiin and phthalonitr...A novel conjugated polymer which shows sendconductivity at T < 260K and T >286K and metallic conductivity at 260K < T< 286K was syllthesized by reaction of 2, 3, 5, 6-tetracyano1, 4-dithiin and phthalonitrile with CuCl2.2H2O.展开更多
INTRODUCTIONIn 1976, Alan MacDiarmid, Hideki Shirakawa and I, together with a talented group of graduate students andpost-doctoral researchers discovered conducting polymers and the ability to dope these polymers over...INTRODUCTIONIn 1976, Alan MacDiarmid, Hideki Shirakawa and I, together with a talented group of graduate students andpost-doctoral researchers discovered conducting polymers and the ability to dope these polymers over the fullrange from insulator to metal. This was particularly exciting because it created a new field of research on theboundary between chemistry and condensed matter physics, and because it created a number of opportunities:展开更多
Covalent organic frameworks（COFs） as an emerging class of porous materials have achieved remarkable progress in recent years.Their high surface area,low mass densities,highly ordered periodic structures,and ease of ...Covalent organic frameworks（COFs） as an emerging class of porous materials have achieved remarkable progress in recent years.Their high surface area,low mass densities,highly ordered periodic structures,and ease of functionalization make COFs exhibit superior potential in gas storage and separation,optoelectronic device and catalysis.This mini review gives a brief introduction of COFs and highlights their applications in electronic and optical fields.展开更多
A three-stage MMIC power amplifier operating from 6to 18GHz is fabricated using 0.25μm A1GaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor（PHEMT）.The amplifier isfully monolithic,with all matching,bi...A three-stage MMIC power amplifier operating from 6to 18GHz is fabricated using 0.25μm A1GaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor（PHEMT）.The amplifier isfully monolithic,with all matching,biasing,and DC block circuitry included on the chip.Thepower amplifier has an average power gain of 19dB over 6～18GHz.At operation frequenciesfrom 6 to 18GHz,the output power is above 33.3dBm,and the maximum output power of the MMICis 34.7dBm at 10Ghz.The input return loss is less than-10db and the out-put return is lessthan-6dB over operating frequency.This power amplifier has,to our knowledge,the best powergain flatness reported at C-X-Ku-band applications.展开更多
This paper reports the high-energy proton irradiation effects on GaAs/Ge space solar cells. The solar cells were irradiated by protons with energy of 5-20 MeV at fluence ranging from 1×109 to 7×1013 cm-2, an...This paper reports the high-energy proton irradiation effects on GaAs/Ge space solar cells. The solar cells were irradiated by protons with energy of 5-20 MeV at fluence ranging from 1×109 to 7×1013 cm-2, and then their electric parameters were measured at AM0. It was shown that the Isc, Voc and Pmax decrease as the proton energy increasing, and the degradation is relative to proton irradiation-induced defect with a level of Ec-0.41 eV in irradiated GaAs/Ge cells.展开更多
Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analys...Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.展开更多
An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and...An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs.展开更多
The electrochemical behaviour and passive film properties of Fe-Cr-Mo-W-C-B-Y amorphous alloys in acetic acid solution were investigated. The potentiodynamic polarisation and Nyquist curves demonstrated that W additio...The electrochemical behaviour and passive film properties of Fe-Cr-Mo-W-C-B-Y amorphous alloys in acetic acid solution were investigated. The potentiodynamic polarisation and Nyquist curves demonstrated that W addition signifi- cantly enhanced the corrosion resistance. Mott-Schottky plots and angle-resolved X-ray photoelectron spectra indicated that passive films with different W contents exhibited dipolar （p-n） semiconducting characteristics separated by fiat-band potentials. The outer and inner oxide layers of the passive films were modified by reducing the acceptor and donor densities. Moreover, W addition favoured the formation of a thicker and more stable passive film to inhibit the dissolution of alloy elements.展开更多
Semiconducting conjugated polymer nanoparticles(SPNs)represent an emerging class of phototheranostic materi-als with great promise for cancer treatment.In this report,low-bandgap electron donoracceptor(DA)-conjugated ...Semiconducting conjugated polymer nanoparticles(SPNs)represent an emerging class of phototheranostic materi-als with great promise for cancer treatment.In this report,low-bandgap electron donoracceptor(DA)-conjugated SPNs with sur-face cloaked by red blood cell membrane(RBCM)are developed for highly e ective photoacoustic imaging and photothermal therapy.The resulting RBCM-coated SPN(SPN@RBCM)displays remarkable near-infrared light absorption and good photosta-bility,as well as high photothermal conver-sion e ciency for photoacoustic imaging and photothermal therapy.Particularly,due to the small size(<5 nm),SPN@RBCM has the advantages of deep tumor penetration and rapid clearance from the body with no appreciable toxicity.The RBCM endows the SPNs with prolonged systematic circulation time,less reticuloendothelial system uptake and reduced immune-recognition,hence improving tumor accumulation after intravenous injection,which provides strong photoacoustic signals and exerts excellent photothermal therapeutic e ects.Thus,this work provides a valuable paradigm for safe and highly e cient tumor pho-toacoustic imaging and photothermal therapy for further clinical translation.展开更多
文摘Over the past half-century,significant efforts have been dedicated to the photocatalytic H_(2)production from H_(2)O under UV–visible light irradiation.These endeavors have yielded remarkable results,with efficiency levels now approaching near 100%apparent quantum yields,notably utilizing inorganic semiconducting materials such as modified Al-doped SrTiO_(3)photocatalysts.Meanwhile,advancements in organic polymer semiconducting materials,exemplified by g-C_(3)N_(4),have led to substantial improvements in the efficiency of photocatalytic overall water splitting for H_(2)evolution reaction.These improvements,achieved through chemical engineering methods and molecular-level modifications,have resulted in an apparent quantum yield of 69%at 405 nm,accompanied by significant red-shifting of optical absorption to 1400 nm.These developments are presented in chronological order over the past half-century,underscoring the ongoing quest for innovative breakthroughs to enable largescale practical applications of solar hydrogen production.Key considerations in this pursuit include efficiency,stability,cost-effectiveness,and the independent evolution of H_(2)and O_(2).
基金supported by the National Natural Science Foundation of China (No. 62204079)the Science and Technology Development Project of Henan Province (Nos.202300410048, 202300410057)+2 种基金the China Postdoctoral Science Foundation (No. 2022M711037)the Intelligence Introduction Plan of Henan Province in 2021 (No. CXJD2021008)Henan University Fund。
文摘Quantum dot(QD)-based infrared photodetector is a promising technology that can implement current monitoring,imaging and optical communication in the infrared region. However, the photodetection performance of self-powered QD devices is still limited by their unfavorable charge carrier dynamics due to their intrinsically discrete charge carrier transport process. Herein, we strategically constructed semiconducting matrix in QD film to achieve efficient charge transfer and extraction.The p-type semiconducting CuSCN was selected as energy-aligned matrix to match the n-type colloidal PbS QDs that was used as proof-of-concept. Note that the PbS QD/CuSCN matrix not only enables efficient charge carrier separation and transfer at nano-interfaces but also provides continuous charge carrier transport pathways that are different from the hoping process in neat QD film, resulting in improved charge mobility and derived collection efficiency. As a result, the target structure delivers high specific detectivity of 4.38 × 10^(12)Jones and responsivity of 782 mA/W at 808 nm, which is superior than that of the PbS QD-only photodetector(4.66 × 10^(11)Jones and 338 mA/W). This work provides a new structure candidate for efficient colloidal QD based optoelectronic devices.
文摘In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.
基金supported by the National Natural Science Foundation of China(Nos.52371203,51971221 and 52031014).
文摘Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a two-dimensional (2D) tetragonal organic-inorganic ferrimagnetic (FIM) semiconductor of Fe_(14)Se_(16)(peha)_(0.7) (peha = pentaethylenehexamine) with excellent thermal stability and a Curie temperature (T_(C)) higher than 519 K. Magnetic and Mössbauer measurements reveal a long-range magnetic ordering in single crystalline Fe_(14)Se_(16)(peha)0.7 nanosheets. The saturation magnetization and coercivity are 5.9 emu g^(−1) and 0.42 kOe at 5 K, which slightly reduces to 4.6 emu g^(−1) and ∼0 Oe at 300 K. A direct optical bandgap of 2.22 eV is obtained by tuning electronic structure of β-Fe3Se4 host layers through spacer layers consisting of Fe^(3+) and peha. Electrical and Seebeck coefficient data indicate that the n-type semiconductor follows the thermally-activated conduction mechanism (lnρ ∝ T^(−1)) in a range of 130–300 K with an activation energy (Ea) of 62.69 meV. Thermal conductivity is 2.5 W m^(−1) K^(−1) at 300 K, while the Wiedemann–Franz law is strongly violated according to electrical-thermal transport data due to weak incorporation of organic spacer layers and host layers. This study sets the stage for exploiting new room-temperature organic magnetic semiconductor systems for spintronic materials.
基金supported by the National Natural Science Foundation of China(Nos.52130209,51927803,52188101,52372054,and 22003074)the National Key R&D Program of China(No.2022YFA1203302)+2 种基金Guangdong Provincial Key Laboratory Program of the Guangdong Science and Technology Department(No.2021B1212040001)the Youth Innovation Promotion Association CAS(No.2022366)Shenzhen Science and Technology Program(No.JCYJ20240813154813018).
文摘Horizontally aligned semiconducting single-wall carbon nanotube(s-SWCNT)arrays are ideal candidates for next-generation integrated circuits.However,the mainstream synthesis methods for obtaining s-SWCNTs mainly utilize the differences in structure and chemical reactivity between them and their metallic counterparts.These differences are too small to greatly improve their purity and reproducibility.Here we report an energy engineering strategy to expand the etching energy barrier difference of SWCNTs with different conductivities.In addition to density functional theory calculations on the energy barrier change,hydrogenation of single-wall carbon nanotubes(SWCNTs)by hydrogen plasma treatment and reversible dehydrogenation by annealing were realized experimentally.The structure-dependent hydrogenation and following selective oxidative etching of SWCNTs were demonstrated.As a result,horizontally aligned s-SWCNT arrays with high purity were obtained.
基金the Fundamental Research Funds for the Central Universities(No.buctrc202103)the National Natural Science Foundation of China(Nos.52373170,22171019)+1 种基金Beijing Natural Science Foundation(No.2252015),SINOPEC(No.225057)Open Project Program of the State Key Laboratory of Fine Chemicals(No.KF2201,Dalian University of Technology)。
文摘Intrinsically stretchable semiconducting polymers play a vital role in the development of wearable electronics,featuring low-cost,large-area and high-density fabrication.Only single-stage dynamic chemical bond has been widely incorporated into polymer backbones to afford stretchability while multiple dynamic bonds have not been investigated,making a formidable challenge to achieve high stretchability without compromising charge transport properties.Herein,we synthesize a series of stretchable polymer semiconductors incorporating urethane and bipyridine units,which can provide dynamic interconnected polymer network by combination of hydrogen bonds with metal coordination,simultaneously obtaining excellent stretchability and carrier mobilities.Compared with single-stage hydrogen bonds,multiple dynamic chemical bonds constructed by 10% hydrogen bonds and 0.25 equiv.metal coordination endowed the polymer semiconductors with an 58% enhancement in carrier mobility and a two-fold increase in crack-onset strain.Notably,the polymer exhibited stable carrier mobilities parallel to the stretching direction,with 91% of initial values even under 150% strain,which is the unprecedented value for intrinsically stretchable semiconducting polymers without blending of elastomers.Therefore,the introduction of multiple dynamic bonds provides an effective and promising approach for intrinsically stretchable and high-performance polymer semiconductor.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204521,12250710675,and 12504198)the National Key R&D Program of China(Grant No.2022YFA1403000)。
文摘SrRuO_(3)is a canonical itinerant ferromagnet,yet its properties in the extreme two-dimensional limit on a(111)crystal plane remain largely unexplored.Here,we demonstrate a complete transformation of its ground state driven by dimensional reduction.As the thickness of(111)-oriented SrRuO_(3)films is reduced to a few unit cells,the system transitions from a metallic ferromagnet to a semiconducting antiferromagnet.This emergent antiferromagnetism is evidenced by a vanishing magnetic remanence and most strikingly,by the appearance of an unconventional twelve-fold anisotropic magnetoresistance.First-principles calculations confirm that an A-type antiferromagnetic order is the stable ground state in the ultrathin limit.Our findings establish(111)dimensional engineering as a powerful route to manipulate correlated electron states and uncover novel functionalities for antiferromagnetic spintronics.
基金supported by the Scientific and Technological Research of the Chongqing Municipal Education Commission(Grant No.KJZD-K202100602)the funding from the Institute for Advanced Sciences of Chongqing University of Posts and Telecommunications(Grant No.E011A2022326)partially supported by the RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic(Grant No.A1898b0043 for G.Z.)。
文摘Two-dimensional nanostructures shed new light on the enhancement of the thermoelectric figure of merit due to the potential decoupling of electronic and phononic transport coefficients.In contrast to the gapless character of graphene-like silicene,a recently reported silicon allotropy with a honeycomb-kagome lattice is a semiconductor.Here,based on first-principles calculations,we set out to investigate the thermoelectric transport performance of this semiconducting silicene.Since the mean free path of a large number of phonons in this structure is less than the Ioffe–Regel limit,we employ the quantum Boltzmann transport equation(BTE)method to obtain an accurate prediction of lattice thermal conductivity.Importantly,we unexpectedly find much lower lattice thermal conductivity compared to that of graphene-like silicene,i.e.,about 1.73W·m^(−1)·K^(−1)at room temperature.Meanwhile,the electronic transport coefficient is calculated within the strictly electron–phonon coupling calculation and a full solution of the electron BTE.The optimal thermoelectric figure of merit ZT reaches 3.2 in N-doped silicene at 700K with an optimized low carrier concentration of 8×10^(10)cm^(−2),which is a recorded value among two-dimensional materials.Our work paved the way for applications of silicon-based two-dimensional materials in on-chip thermoelectric cooling and clean energy.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1408400,2023YFA1406100,2023YFA1607400,2022YFA1403800,and 2022YFA1403203)the National Natural Science Foundation of China(Grant Nos.12474055,12404067,12025408,52025026,and U23A6003)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2024PG0003)the Outstanding Member of Youth Promotion Association of Chinese Academy of Sciences(Grant No.Y2022004)supported by the CAC station of Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF)。
文摘Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.
基金financially supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(Nos.2022K1A3A1A20014496 and RS-2023-00284318)
文摘Real-time detection of acetic acid vapor is of concern for ensuring environmental and personal safety.However,acetic acid gas sensors,particularly those based on Bi_(2)O_(3),often fail to meet practical performance requirements owing to their slow response characteristics and high operating temperature.To enhance sensing performance,highly permeable Bi_(2)O_(3)microspheres decorated by Pt-nanoparticles are rationally synthesized by a facile template method.Among the fabricated sensors,the one based on 3 wt%Pt-decorated Bi_(2)O_(3)demonstrated excellent sensing performance.Specifically,the sensor displayed high selectivity for acetic acid,rapid response and recovery times(22.5 and 9 s,respectively),strong resistance to interference,and good long-term stability at a low operating temperature(150℃).Notably,the sensor exhibited an exceptionally high response of 126 to 100 ppm acetic acid—the highest reported value for Bi_(2)O_(3)-based sensors tested at a relatively low operating temperature in recent years.These results demonstrate that Pt-decorated Bi_(2)O_(3)holds strong potential for use in high-performance acetic acid sensors.
文摘This work presents the electronic behavior of Ti and TiN thin films when exposed to electrolytes with pH levels of 2,7 and 13 for 90 days.Staircase potentio-electrochemical impedance spectroscopy tests were performed on the 100-nm Ti and TiN monolithic films,and MottSchottky analysis of these tests was used to determine the films’ semiconductive behavior and changes in the donor/acceptor density.In addition,the flat-band potential of each film’s surface oxide was also characterized.No attempt was made to control oxide formation,and therefore,these tests reflected the native surfaces of these films.While the TiN films exhibited n-type semiconductivity in all electrolytes,the Ti films only showed n-type behavior in the acidic(pH=2) and neutral(pH=7) electrolytes.The semiconductivity of the Ti films transitioned to p-type during exposure to the basic electrolyte(pH=13) after reaching 60 days.Furthermore,there was a significant increase in the donor densities for both Ti and TiN films when immersed in the basic electrolyte relative to the acidic and neutral electrolytes.
文摘A novel conjugated polymer which shows sendconductivity at T < 260K and T >286K and metallic conductivity at 260K < T< 286K was syllthesized by reaction of 2, 3, 5, 6-tetracyano1, 4-dithiin and phthalonitrile with CuCl2.2H2O.
基金The copyright of this paper is owned by the Nobel Foundation.
文摘INTRODUCTIONIn 1976, Alan MacDiarmid, Hideki Shirakawa and I, together with a talented group of graduate students andpost-doctoral researchers discovered conducting polymers and the ability to dope these polymers over the fullrange from insulator to metal. This was particularly exciting because it created a new field of research on theboundary between chemistry and condensed matter physics, and because it created a number of opportunities:
基金the 973 Program(No.2013CB834704)the National Natural Science Foundation of China(Nos.21471018,21201018,21404010)1000 Plan (Youth) for financial support
文摘Covalent organic frameworks（COFs） as an emerging class of porous materials have achieved remarkable progress in recent years.Their high surface area,low mass densities,highly ordered periodic structures,and ease of functionalization make COFs exhibit superior potential in gas storage and separation,optoelectronic device and catalysis.This mini review gives a brief introduction of COFs and highlights their applications in electronic and optical fields.
文摘A three-stage MMIC power amplifier operating from 6to 18GHz is fabricated using 0.25μm A1GaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor（PHEMT）.The amplifier isfully monolithic,with all matching,biasing,and DC block circuitry included on the chip.Thepower amplifier has an average power gain of 19dB over 6～18GHz.At operation frequenciesfrom 6 to 18GHz,the output power is above 33.3dBm,and the maximum output power of the MMICis 34.7dBm at 10Ghz.The input return loss is less than-10db and the out-put return is lessthan-6dB over operating frequency.This power amplifier has,to our knowledge,the best powergain flatness reported at C-X-Ku-band applications.
基金supported by Visiting Scholar Foundation of Key LaboratoryMinistry of Education,China and Initiative Foundation of Scaence and Technology,Beijing
文摘This paper reports the high-energy proton irradiation effects on GaAs/Ge space solar cells. The solar cells were irradiated by protons with energy of 5-20 MeV at fluence ranging from 1×109 to 7×1013 cm-2, and then their electric parameters were measured at AM0. It was shown that the Isc, Voc and Pmax decrease as the proton energy increasing, and the degradation is relative to proton irradiation-induced defect with a level of Ec-0.41 eV in irradiated GaAs/Ge cells.
基金supported by the National Key R&D Program of China(No.2020YFB2008604,2021YFB3202500)the National Natural Science Foundation of China(No.61874034)the International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300)。
文摘Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.
基金supported by National Natural Science Foundation of China No.50730008Shanghai Science and Technology Grant No.0752nm015National Basic Research Program of China No.2006CB300406
文摘An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs.
基金supported by the National Natural Science Foundation of China(Nos.51601129 and 51401051)the Shanghai Pujiang Program(16PJ1410000)
文摘The electrochemical behaviour and passive film properties of Fe-Cr-Mo-W-C-B-Y amorphous alloys in acetic acid solution were investigated. The potentiodynamic polarisation and Nyquist curves demonstrated that W addition signifi- cantly enhanced the corrosion resistance. Mott-Schottky plots and angle-resolved X-ray photoelectron spectra indicated that passive films with different W contents exhibited dipolar （p-n） semiconducting characteristics separated by fiat-band potentials. The outer and inner oxide layers of the passive films were modified by reducing the acceptor and donor densities. Moreover, W addition favoured the formation of a thicker and more stable passive film to inhibit the dissolution of alloy elements.
基金supported by the National Natural Science Foundation of China(Grant Nos.61727823,51873160)the joint research project of Health and Education Commission of Fujian Province(Grant No.2019-WJ-20).
文摘Semiconducting conjugated polymer nanoparticles(SPNs)represent an emerging class of phototheranostic materi-als with great promise for cancer treatment.In this report,low-bandgap electron donoracceptor(DA)-conjugated SPNs with sur-face cloaked by red blood cell membrane(RBCM)are developed for highly e ective photoacoustic imaging and photothermal therapy.The resulting RBCM-coated SPN(SPN@RBCM)displays remarkable near-infrared light absorption and good photosta-bility,as well as high photothermal conver-sion e ciency for photoacoustic imaging and photothermal therapy.Particularly,due to the small size(<5 nm),SPN@RBCM has the advantages of deep tumor penetration and rapid clearance from the body with no appreciable toxicity.The RBCM endows the SPNs with prolonged systematic circulation time,less reticuloendothelial system uptake and reduced immune-recognition,hence improving tumor accumulation after intravenous injection,which provides strong photoacoustic signals and exerts excellent photothermal therapeutic e ects.Thus,this work provides a valuable paradigm for safe and highly e cient tumor pho-toacoustic imaging and photothermal therapy for further clinical translation.
