Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling pha...Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging.In this study,we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions.Raman spectroscopy,atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures.Atomic-scale scanning tunneling microscopy/spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures,where positive bias voltage induces in a pronounced superposition of the√13×√13 CDW of the 1T-layer on the 1H-layer.By systematically comparing the 1T/1H and 1T/1T interfaces,we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer,suppressing the formation of CDW domain walls and forming more ordered electronic states.These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.展开更多
Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics...Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.展开更多
The enhancement of perpendicular magnetic anisotropy(PMA)is critical for the continuous growth of magnetic memory density.Material systems that possess high interfacial PMA typically involve strong spin-orbit coupling...The enhancement of perpendicular magnetic anisotropy(PMA)is critical for the continuous growth of magnetic memory density.Material systems that possess high interfacial PMA typically involve strong spin-orbit coupling(SOC)or transition metal/oxide interfaces.In contrast,the role of 3d light metals in enhancing the interfacial PMA has been less investigated.This study demonstrated that the insertion of a few atomic Cr layers into Pt/Co/Pt/Ta heterostructures with Cr between the 1 atomic Pt layer and the 3 nm Ta overlayer enhanced the effective PMA energy(K_(eff))by a factor of 4.First-principles calculations revealed that the underlying mechanism originated from Cr-Pt d-orbital hybridization,leading to a corresponding orbital redistribution and significantly increasing the magnetic anisotropy energy.The progressive reduction in the spin-orbit torque(SOT)efficiency with increasing Cr thickness might stem from the enhanced orbital Rashba–Edelstein effect at the Pt/Cr interface.Furthermore,the wedging of a few atomic Cr layers caused the robust field-free SOT switching of perpendicular magnetization,which was due to the lateral PMA gradients enabled by the strong dependence of the PMA on the Cr thickness.The results provide a method for interfacial PMA enhancement by d-orbital hybridization of 3d–5d electrons and an alternative to field-free SOT switching towards low-power and high-density memory applications.展开更多
Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,a...Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,and tunable emission wavelengths.Achieving high-performance perovskite LEDs(Pe LEDs)requires the emissive layer to possess efficient radiative recombination,low defect density,minimal ion mobility,and effective carrier confinement.Perovskite/perovskite heterostructure(PPHS)offers a compelling approach for engineering emissive layers with these desired attributes,owing to their ability to passivate surface defects,tailor bandgaps,and suppress ion migration.Pe LEDs based on PPHS have demonstrated superior performance compared to single-phase devices,particularly in terms of external quantum efficiency and operational stability.This review provides a comprehensive overview of the typical PPHS architectures applied in Pe LEDs,including vertical,lateral,and bulk configurations.We discuss representative fabrication strategies and the associated optoelectronic properties of these heterostructures,highlighting the mechanisms by which they enhance device efficiency and stability.Finally,we explore the remaining challenges and prospects for the application of PPHS in Pe LEDs and other luminescent technologies.展开更多
MnO_(2) emerges as a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity and ideal working voltage.However,inherent limitations in low electrical conductivity and struc...MnO_(2) emerges as a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity and ideal working voltage.However,inherent limitations in low electrical conductivity and structural instability restrict its widespread application.Herein,we fabricated layered δ-MnO_(2) and introduced Cu and Ce metal ions for structural regulation,thus constructing a δ/a-MnO_(2) heterostructure within the δ-MnO_(2) matrix,forming a heterointerface that simultaneously enhances the electrical conductivity and structural stability of the material.In this system,Cu^(2+)acts as a catalyst,promoting the reduction of high-valent Mn to Mn^(2+)and enabling local two-electron transfer,which significantly increases the discharge specific capacity of MnO_(2).For Ce^(3+),it functions as a structural regulator,inducing the partial transformation of δ-MnO_(2) to a-MnO_(2) and forming the δ/a-MnO_(2) heterostructure.Further supported by density functional theory(DFT)calculations and in-situ characterization results,the heterointerface between a-MnO_(2) andδ-MnO_(2) generates an internal electric field due to the difference in Fermi levels.This not only effectively enhances the electron transfer capability but also significantly improves structural stability.Benefiting from these advantages,the Cu,Ce co-incorporated MnO_(2)(CCMO)cathode delivers a high discharge capacity of 455.4 mAh g^(-1)at 0.2 A g^(-1)and maintains 191.2 mAh g^(-1)specific capacity after 1500 cycles with 95%capacity retention at 2 A g^(-1),which is significantly better than non-doped MnO_(2).This strategy of structural regulation and heterostructure construction using vip ions offers a new approach for developing high-performance Mn-based cathode materials for AZIBs.展开更多
Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promisin...Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promising strategy to address this issue.To realize the synergy,herein,Sn whiskers with an in situ oxide layer served as substrates for magnetic-loss-active CoNi nanosheet growth,forming a hierarchical CoNi@SnO_(2)@Sn(CNS)heterostructure.The CNS absorber achieves a minimum reflection loss(RL_(min))value of-62.29 dB with an effective absorption bandwidth(EAB)of 2.2 GHz,covering the entire C-band with 70%absorption at only 2.61 mm thickness.The nanosheet design of CoNi enhances magnetic anisotropy to promote natural resonance,while the conductive Sn core and abundant Sn/SnO_(2) and CoNi/SnO_(2) heterointerfaces facilitate conduction loss and dielectric polarization.When composited into a thermoplastic polyurethane(TPU)matrix,the resulting CNS/TPU-2 film(20 wt%CNS)exhibits an RL_(min) value of-61.04 dB and a 2.5 GHz EAB.Its in-plane and through-plane thermal conductivities reach 2.41 and 0.51 W m^(-1) K^(-1),representing 4.1 and 2.6 times those of pure TPU films,respectively,facilitating heat dissipation from protected devices.This work provides valuable insights into magnetic-dielectric synergy for low-frequency MA of 1D metal-based materials,offering promising potential for 5G communications and flexible electronics.展开更多
The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising c...The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.展开更多
Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heter...Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heterogeneous zones.However,the synergistic strengthening mechanism and deformation behavior among multi-scale heterostructures are still unclear.In this work,AZ80/AZ31 laminate with a multi-scale heterogeneous distribution of grain size,precipitates,and texture between alternate AZ31 and AZ80 component layers,which was constructed by accumulative extrusion bonding combined with aging treatment.The composite samples after 2-pass extrusion presented an outstanding strength-ductility synergy,which was attributed to the joint action of texture softening and hardening,grain refinement as well as multistage heterogeneous deformation induced(HDI)strengthening and hardening.Multi-types of heterogeneous regions provided more sites for geometrically necessary dislocation accumulation to accommodate multiple strain gradients under the constraint of multi-layer interfaces,enhancing HDI stress.The synergistic effect of great Schmid factor difference and increasing geometric compatibility factor between adjacent grains at the layer interface led to strain transfer behavior,which facilitated strain delocalization.This work expands the design ideas and preparation methods of heterostructured materials and enriches the theory of heterogeneous deformation.展开更多
The design and development of high-performance electrocatalysts for the hydrogen evolution reaction(HER)are essential for advancing the hydrogen economy.The electronic structure and core size of an electrocatalyst are...The design and development of high-performance electrocatalysts for the hydrogen evolution reaction(HER)are essential for advancing the hydrogen economy.The electronic structure and core size of an electrocatalyst are pivotal for determining the intrinsic activity of the catalytic sites.Interfacial engineering,particularly the formation of well-controlled core-shell heterostructures,has emerged as a promising strategy,although significant challenges remain.Here,we present a series of Ru@NC heterostructures with size-controlled Ru cores encapsulated in N-doped graphene layers.Among these,Ru@NC-3h,with the best holistic effects,has superior durability and mass activity 7.03 times that of Pt/C.This high performance is attributed to the open porous structure,which enhances active site exposure and mass transfer,and the optimized adsorption and desorption of reaction intermediates by the strengthened heterointerfacial interaction between the smaller Ru cores and thin N-doped shells.Attenuated total reflectance surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)reveals reinforced interfacial water interaction and reduced hydrogen adsorption.Density functional theory(DFT)calculations indicate that the size effect promotes interfacial H_(2)O adsorption,whereas the electronic effect governs ^(*)H adsorption to collectively accelerate the HER kinetics.This novel strategy,introduced to regulate heterostructures through size and electronic effects,offers significant potential for various energy material applications.展开更多
As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM c...As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.展开更多
The imperative quest for renewable energy sources and advanced energy storage technologies has arisen amidst the escalating perils of climate change and dwindling fossil fuel reserves.In the realm of energy storage te...The imperative quest for renewable energy sources and advanced energy storage technologies has arisen amidst the escalating perils of climate change and dwindling fossil fuel reserves.In the realm of energy storage technologies,asymmetric supercapacitor(ASC)has garnered significant attention owing to its high energy density and power density.In the quest for advanced electrode materials for ASC,the integration of 2D layered heterostructures on hierarchical porous carbon(HPC)substrates has emerged as a promising approach to enhance the electrochemical performance.Herein,a highly innovative hierarchical NiCo LDH/MoS_(2)/HPC heterostructure was successfully synthesized using a simple two-step hydrothermal method for the electrode materials of ASC.Benefiting from the unique hierarchical heterostructure of NiCo LDH/MoS_(2)/HPC composite and the synergistic effect between the components,it reveals an exceptional specific capacitance of 2368 F/g at 0.5 A/g in a three-electrode system,which significantly exceeds that of conventional supercapacitor electrodes.Additionally,the ASC device of NiCo LDH/MoS_(2)/HPC//HPC achieves remarkable specific capacitance of 236 F/g at 0.5 A/g and an impressive energy density of 84Wh/kg at a power density of 400 W/kg,as well as superior cyclic stability.This study not only demonstrates the effectiveness of incorporating MoS_(2) and NiCo LDH into a carbon-based framework for supercapacitor applications but also opens avenues for designing more efficient energy storage devices.展开更多
The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromag...The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromagnetic waves(EMW).Herein,a rational and universally applicable two-step hydrothermal method strategy was proposed to effectively control the electronic structure of Mott-Schottky EMW absorbing materials derived from Co-MOF.The as-synthesized Co_(3)S_(4)@MoS_(2)/NC ensures efficient electron transfer,while the change redistribution leads to the emergence of additional electric dipoles under an external EMM field.In addition,the hierarchical Co_(3)S_(4)@MoS_(2)/NC nano-architecture with a hierarchical arrange-ment in 2D and 3D offers more polarization sites,thereby extending the path for EMW transmission through multiple reflections and scattering.The potential to enhance the EMW absorption performance of Co_(3)S_(4)@MoS_(2)/NC lies in its unique microstructure and substantial surface area,which optimize impedance matching properties through a synergistic effect of dipole and interfacial polarization induced by Mott-Schottky heterointerfaces.As anticipated,the Co_(3)S_(4)@MoS_(2)/NC exhibits a maximum EMW absorption ca-pacity with an RLmin value of-41.97 dB and a broad EAB of 4.24 GHz at a thickness of 2.0 mm.This study provides insights for designing highly efficient Mott-Schottky EMW absorbing materials at the molecular level rationally.展开更多
Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching a...Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching angle shift”, where the applied direct current is assumed to shift, via domain wall depinning during anti-domain expansion, the switching angle of a perpendicular magnetization in a linear proportional manner under a large rotating magnetic field. Here, we report that, for the most commonly employed perpendicular magnetization heterostructures in spintronics(e.g., those based on FeCoB, Co, and Co/Ni multilayers), the switching angle shift considerably misestimates the SOT within the domain wall depinning analysis of the slope of linear-in-current scaling and may also have a non-zero residual value at zero direct current. Our experiments and simulations unveil that the switching angle shift is most likely dominated by chiral asymmetric nucleation rather than expansion of anti-domains. The in-plane field from external magnets and current-induced SOTs lowers the perpendicular nucleation field and thus reduces the required switching angle, ultimately leading to an underestimation of SOTs by domain wall depinning analysis. These results have advanced our understanding of magnetization switching in spintronic devices.展开更多
Research on p-channel field-effect transistors(p-FETs)remains limited,primarily due to the significantly lower conductivity of the two-dimensional hole gas(2DHG)compared to the two-dimensional electron gas(2DEG)in n-c...Research on p-channel field-effect transistors(p-FETs)remains limited,primarily due to the significantly lower conductivity of the two-dimensional hole gas(2DHG)compared to the two-dimensional electron gas(2DEG)in n-channel field-effect transistors(n-FETs),which poses a significant challenge for monolithic integration.In this study,we investigate the impact of epitaxial structure parameters on 2DHG properties in p-Ga N/Al Ga N/Ga N heterostructures through semiconductor technology computer-aided design(TCAD)simulations and theoretical calculations,identifying the conditions necessary to achieve high-density 2DHG.Our simulations demonstrate that increasing the p-Ga N thickness leads to two critical thicknesses determined by surface states and acceptor ionization concentration:one corresponds to the onset of 2DHG formation,and the other to its saturation.Lowering the donor surface state energy level and increasing the acceptor ionization concentration promote 2DHG formation and saturation,although the saturated density remains independent of surface states.Additionally,a higher Al composition enhances intrinsic ionization due to stronger polarization effects,thereby increasing the 2DHG sheet density.Consequently,to achieve high-density 2DHG in p-Ga N/Al Ga N/Ga N heterostructures,it is essential to increase the Al composition,ensure that the p-Ga N thickness exceeds the critical thickness for 2DHG saturation,and maximize the acceptor ionization concentration.This study elucidates the impact of epitaxial structure parameters on 2DHG properties in p-Ga N/Al Ga N/Ga N heterostructures and provides valuable guidance for the optimization of p-FET designs.展开更多
The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-li...The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-like Bi_(2)Fe_(4)O_(9)@Polypyrrole(BFO@PPy)heterostructure was successfully designed and fabricated using an efficient microwave hydrothermal method and an in situ polymerization process.Specifically,Bi_(2)Fe_(4)O_(9)enhances the chemical activity of ammonium persulfate,which in turn initiates the polymerization of pyrrole monomers,resulting in the formation of BFO@PPy heterostructures.The thickness of the PPy coating layer in the BFO@PPy composite can be precisely controlled at the nanoscale,optimizing electromagnetic parameters,conduction losses and interface polarization loss.The fabricated BFO@PPy composite achieves a minimum reflection loss(RL_(min))of-57.8 dB at a thickness of 2.5 mm and an effective absorption bandwidth(EAB)of 6.96 GHz.Furthermore,the EMW absorption performance and mechanism were systematically validated through theoretical calculations,radar cross-sectional simulations(RCS),and first-principles analysis.Notably,the RCS simulation of a 1:1 scale F-22 Raptor fighter model provides a realistic evaluation of the composite's EMW absorption potential in military applications.The efficient fabrication method and superior electromagnetic absorption performance make BFO@PPy a promising candidate for use in complex electromagnetic environments and military domains.Additionally,the BFO@PPy composite exhibits rapid electrothermal conversion at a low voltage(3V),achieving active infrared camouflage within a controllable temperature range,further highlighting its multifunctional properties.展开更多
Structured design helps to play out the coordination advantage and optimize the performance of electro-chemical reactions.In this work,hierarchical hollow microspheres(Co_(3)S_(4)@NiCo_(2)S_(4)) with unique core-shell...Structured design helps to play out the coordination advantage and optimize the performance of electro-chemical reactions.In this work,hierarchical hollow microspheres(Co_(3)S_(4)@NiCo_(2)S_(4)) with unique core-shell heterostructure were successfully prepared through simple template and solvothermal methods.Thanks to the hollow structure,cross-linked nanowire arrays,and in-situ coating of zeolite imidazole framework(ZIF),Co_(3)S_(4)@NiCo_(2)S_(4) demonstrated excellent electrochemical performance with a specific ca-pacitance of up to 2697.7 F g^(-1)at 1 A g^(-1) and cycling stability of 80.5% after 5000 cycles.The covalent organic framework(COF)derived nano carbon,which had undergone secondary calcination and ZnCl_(2) activation,also exhibited excellent double-layer energy storage performance.Compared to a single calci-nation,the incredible increase in capacitance was up to 208.5 times greater,reaching 291.9 F g^(-1)at 1 A g^(-1)while maintaining ultra-high rate performance(81.0%at 20 A g^(-1)).The hybrid supercapacitor,assem-bled with Co_(3)S_(4)@NiCo_(2)S_(4)as the cathode and COF-derived carbon as the anode,exhibited an extremely high energy density(79.7 Wh kg^(-1)at 693.5 W kg^(-1))and excellent cyclic stability(maintained 79.3%after 10,000 cycles of 20 A g^(-1)),further explaining the reliable and practical characteristics.This work provided reference for the structural optimization of transition metal sulfides and the high-temperature activation of COF-derived carbon.展开更多
The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that c...The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that can efficiently convert CO_(2) into value-added products,is receiving widespread attention.This article reviews the current research status of Cu/metal oxide heterostructures in the field of electrochemical reduction of CO_(2).The review first introduces the importance of electrochemical reduction of CO_(2) and the application potential of Cu/metal oxide heterostructures in this field.Subsequently,a comprehensive discussion is presented on the exploration of various Cu/metal oxide heterostructures and their corresponding structure-performance relationship,with particular emphasis on the catalysts'activity,selectivity,stability and the nature of active sites.Lastly,the review provides an overview of the current research challenges and future development trends in this field.展开更多
Heterogeneous structure and carbon coating are important ways to enhance the reaction kinetics and cycling stability of metal phosphides as anode materials for sodium-ion batteries.Therefore,nitrogen-doped carbon-capp...Heterogeneous structure and carbon coating are important ways to enhance the reaction kinetics and cycling stability of metal phosphides as anode materials for sodium-ion batteries.Therefore,nitrogen-doped carbon-capped triphasic heterostructure Cu_(3)P/Co_(2)P/CoP@NC stands for nitrogen doped carbon nanorods were designed and synthesized through a combination of phosphide and carbonization.Kinetic analyses(cyclic voltammetry,electrochemical impedance spectroscopy,and galvanostatic intermittent titration technique)and density functional theory calculations show that the three-phase heterostructure and carbon layer effectively improve Na adsorption and migration as well as the electrochemical reactivity of the electrode.Based on this,Cu_(3)P/Co_(2)P/CoP@NC demonstrated excellent rate performance(305.9 mAh g^(-1)at 0.3 A g^(-1)and 202.8 mAh g^(-1)even at 10 A g^(-1))and cycling stability(the capacity decay rate is only 0.12%from the 5th to 300th cycle)when it is used for sodium-ion battery anodes.The in situ X-ray diffraction,ex situ X-ray photoelectron spectroscopy,and high-resolution transmission electron microscopy tests showed that Cu_(3)P/Co_(2)P/CoP@NC is based on a conversion reaction mechanism for sodium-ion storage.In addition,the NVP@reduced graphene oxide(rGO)//Cu_(3)P/Co_(2)P/CoP@NC full-cell delivers a high capacity of 210.2 mAh g^(-1)after 50 cycles at 0.3 A g^(-1).This work can provide a reference for the design of high-performance sodium electrode anode materials.展开更多
Controlling charge polarity in the semiconducting single-walled carbon nanotubes(CNTs) by substitutional doping is a difficult work due to their extremely strong C–C bonding. In this work, an inner doping strategy is...Controlling charge polarity in the semiconducting single-walled carbon nanotubes(CNTs) by substitutional doping is a difficult work due to their extremely strong C–C bonding. In this work, an inner doping strategy is explored by filling CNTs with one-dimensional(1D)-TM_(6)Te_(6) nanowires to form TM_(6)Te_(6)@CNT-(16,0) 1D van der Waals heterostructures(1D-vd WHs). The systematic first-principles studies on the electronic properties of 1D-vd WHs show that N-type doping CNTs can be formed by charge transfer from TM_(6)Te_(6) nanowires to CNTs, without introducing additional carrier scattering.Particularly, contribution from both T M(e.g., Sc and Y) and Te atoms strengthens the charge transfer. The outside CNTs further confine the dispersion of Te-p orbitals in nanowires that deforms the C-π states at the bottom of the conduction band to quasi sp^(3) hybridization. Our study provides an inner doping strategy that can effectively confine the charge polarity of CNTs and further broaden its applications in some novel nano-devices.展开更多
The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectrosc...The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectroscopy to investigate ultrafast electron transport properties in both van der Waals Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)ferromagnetic/topological heterostructures.Our results show that these heterostructures exhibit effective THz electromagnetic shielding.The complex conductivity spectra of Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)heterostructures with varying Fe_(4)GeTe_(2)thicknesses are analyzed using the Drude-Smith model.We quantitatively examine how Fe_(4)GeTe_(2)layer thickness affects the direct current conductivity,plasma frequency,carrier momentum scattering time,and back-scattering coefficient.As the number of Fe_(4)GeTe_(2)layers increases,intra-layer back-scattering events for charge carriers become more frequent.This work provides THz frequency spectra for both Fe_(4)GeTe_(2)and Bi_(2)Te_(3)/Fe_(4)GeTe_(2),aiding in the design and optimization of THz modulators and detectors.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.92477128,92580137,92477205,12374200,11604063,11974422,and 12104504)the National Key R&D Program of China (MOST) (Grant No.2023YFA1406500)+3 种基金the Strategic Priority Research Program (Chinese Academy of Sciences,CAS) (Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China (Grant No.21XNLG27)supported by the Outstanding Innovative Talents Cultivation Funded Programs 2023 of the Renmin University of Chinaan outcome of “Two-dimensional anisotropic series of materials FePd2+xTe2:a structural modulation study from the atomic scale to the mesoscopic scale” (RUC25QSDL128),funded by the “Qiushi Academic-Dongliang” Talent Cultivation Project at Renmin University of China in 2025。
文摘Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging.In this study,we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions.Raman spectroscopy,atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures.Atomic-scale scanning tunneling microscopy/spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures,where positive bias voltage induces in a pronounced superposition of the√13×√13 CDW of the 1T-layer on the 1H-layer.By systematically comparing the 1T/1H and 1T/1T interfaces,we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer,suppressing the formation of CDW domain walls and forming more ordered electronic states.These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.
基金supported by National Natural Science Foundation of China(61921002 and 92163204)。
文摘Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.
基金supported by the “Pioneer” and “Leading Goose” R&D Program of Zhejiang Province (Grant No.2022C01053)the National Natural Science Foundation of China (Grant No.62293493)the Natural Science Foundation of Zhejiang Province,China (Grant No.LQ21A050001)。
文摘The enhancement of perpendicular magnetic anisotropy(PMA)is critical for the continuous growth of magnetic memory density.Material systems that possess high interfacial PMA typically involve strong spin-orbit coupling(SOC)or transition metal/oxide interfaces.In contrast,the role of 3d light metals in enhancing the interfacial PMA has been less investigated.This study demonstrated that the insertion of a few atomic Cr layers into Pt/Co/Pt/Ta heterostructures with Cr between the 1 atomic Pt layer and the 3 nm Ta overlayer enhanced the effective PMA energy(K_(eff))by a factor of 4.First-principles calculations revealed that the underlying mechanism originated from Cr-Pt d-orbital hybridization,leading to a corresponding orbital redistribution and significantly increasing the magnetic anisotropy energy.The progressive reduction in the spin-orbit torque(SOT)efficiency with increasing Cr thickness might stem from the enhanced orbital Rashba–Edelstein effect at the Pt/Cr interface.Furthermore,the wedging of a few atomic Cr layers caused the robust field-free SOT switching of perpendicular magnetization,which was due to the lateral PMA gradients enabled by the strong dependence of the PMA on the Cr thickness.The results provide a method for interfacial PMA enhancement by d-orbital hybridization of 3d–5d electrons and an alternative to field-free SOT switching towards low-power and high-density memory applications.
基金supported by the Advanced Talents Incubation Program of Hebei University(No.521100224235)the National Natural Science Foundation of China(No.52503363)the Natural Science Foundation of Hebei Province(No.E2025201009)。
文摘Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,and tunable emission wavelengths.Achieving high-performance perovskite LEDs(Pe LEDs)requires the emissive layer to possess efficient radiative recombination,low defect density,minimal ion mobility,and effective carrier confinement.Perovskite/perovskite heterostructure(PPHS)offers a compelling approach for engineering emissive layers with these desired attributes,owing to their ability to passivate surface defects,tailor bandgaps,and suppress ion migration.Pe LEDs based on PPHS have demonstrated superior performance compared to single-phase devices,particularly in terms of external quantum efficiency and operational stability.This review provides a comprehensive overview of the typical PPHS architectures applied in Pe LEDs,including vertical,lateral,and bulk configurations.We discuss representative fabrication strategies and the associated optoelectronic properties of these heterostructures,highlighting the mechanisms by which they enhance device efficiency and stability.Finally,we explore the remaining challenges and prospects for the application of PPHS in Pe LEDs and other luminescent technologies.
基金supported by the National Natural Science Foundation of China(no.52574348)the Natural Science Foundation of Hebei Province(nos.E2024501010 and B2024501004)+3 种基金the Shijiazhuang Basic Research Project(no.241790667A)the Fundamental Research Funds for the Central Universities(no.N2423013)the National College Students Innovation and Entrepreneurship Training Program(no.202419145017)the Performance Subsidy Fund for Key Laboratory of Dielectric,Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘MnO_(2) emerges as a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity and ideal working voltage.However,inherent limitations in low electrical conductivity and structural instability restrict its widespread application.Herein,we fabricated layered δ-MnO_(2) and introduced Cu and Ce metal ions for structural regulation,thus constructing a δ/a-MnO_(2) heterostructure within the δ-MnO_(2) matrix,forming a heterointerface that simultaneously enhances the electrical conductivity and structural stability of the material.In this system,Cu^(2+)acts as a catalyst,promoting the reduction of high-valent Mn to Mn^(2+)and enabling local two-electron transfer,which significantly increases the discharge specific capacity of MnO_(2).For Ce^(3+),it functions as a structural regulator,inducing the partial transformation of δ-MnO_(2) to a-MnO_(2) and forming the δ/a-MnO_(2) heterostructure.Further supported by density functional theory(DFT)calculations and in-situ characterization results,the heterointerface between a-MnO_(2) andδ-MnO_(2) generates an internal electric field due to the difference in Fermi levels.This not only effectively enhances the electron transfer capability but also significantly improves structural stability.Benefiting from these advantages,the Cu,Ce co-incorporated MnO_(2)(CCMO)cathode delivers a high discharge capacity of 455.4 mAh g^(-1)at 0.2 A g^(-1)and maintains 191.2 mAh g^(-1)specific capacity after 1500 cycles with 95%capacity retention at 2 A g^(-1),which is significantly better than non-doped MnO_(2).This strategy of structural regulation and heterostructure construction using vip ions offers a new approach for developing high-performance Mn-based cathode materials for AZIBs.
基金supported by the National Natural Science Foundation of China(52171033,52431003,U23A20574)the Fundamental Research Funds for the Central Universities(2242025K20004)the SEU Innovation Capability Enhancement Plan for Doctoral Students(CXJH_SEU 24148,CXJH_SEU 25036).
文摘Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promising strategy to address this issue.To realize the synergy,herein,Sn whiskers with an in situ oxide layer served as substrates for magnetic-loss-active CoNi nanosheet growth,forming a hierarchical CoNi@SnO_(2)@Sn(CNS)heterostructure.The CNS absorber achieves a minimum reflection loss(RL_(min))value of-62.29 dB with an effective absorption bandwidth(EAB)of 2.2 GHz,covering the entire C-band with 70%absorption at only 2.61 mm thickness.The nanosheet design of CoNi enhances magnetic anisotropy to promote natural resonance,while the conductive Sn core and abundant Sn/SnO_(2) and CoNi/SnO_(2) heterointerfaces facilitate conduction loss and dielectric polarization.When composited into a thermoplastic polyurethane(TPU)matrix,the resulting CNS/TPU-2 film(20 wt%CNS)exhibits an RL_(min) value of-61.04 dB and a 2.5 GHz EAB.Its in-plane and through-plane thermal conductivities reach 2.41 and 0.51 W m^(-1) K^(-1),representing 4.1 and 2.6 times those of pure TPU films,respectively,facilitating heat dissipation from protected devices.This work provides valuable insights into magnetic-dielectric synergy for low-frequency MA of 1D metal-based materials,offering promising potential for 5G communications and flexible electronics.
基金financial support from 2024 Domestic Visiting Scholar Program for Teachers'Professional Development in Universities(Grant No.FX2024022)National Natural Science Foundation of China(Grant No.61904043)。
文摘The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China(No.52071035)the Doctoral Scientific Research Foundation of Anhui University of Technology(No.RZ2400002557).
文摘Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heterogeneous zones.However,the synergistic strengthening mechanism and deformation behavior among multi-scale heterostructures are still unclear.In this work,AZ80/AZ31 laminate with a multi-scale heterogeneous distribution of grain size,precipitates,and texture between alternate AZ31 and AZ80 component layers,which was constructed by accumulative extrusion bonding combined with aging treatment.The composite samples after 2-pass extrusion presented an outstanding strength-ductility synergy,which was attributed to the joint action of texture softening and hardening,grain refinement as well as multistage heterogeneous deformation induced(HDI)strengthening and hardening.Multi-types of heterogeneous regions provided more sites for geometrically necessary dislocation accumulation to accommodate multiple strain gradients under the constraint of multi-layer interfaces,enhancing HDI stress.The synergistic effect of great Schmid factor difference and increasing geometric compatibility factor between adjacent grains at the layer interface led to strain transfer behavior,which facilitated strain delocalization.This work expands the design ideas and preparation methods of heterostructured materials and enriches the theory of heterogeneous deformation.
基金supported by the National Natural Science Foundation of China(Nos.22209087,22209186,22479149)the Key Science and Technology Project of Henan Province(No.242102231035)+2 种基金Young Backbone Teacher Training Program of Henan Province Undergraduate Colleges(No.[2024](186))Key Research and Development Program of Jiangxi Province(Nos.20223BBG74004,20232BBG70003)Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2023343)。
文摘The design and development of high-performance electrocatalysts for the hydrogen evolution reaction(HER)are essential for advancing the hydrogen economy.The electronic structure and core size of an electrocatalyst are pivotal for determining the intrinsic activity of the catalytic sites.Interfacial engineering,particularly the formation of well-controlled core-shell heterostructures,has emerged as a promising strategy,although significant challenges remain.Here,we present a series of Ru@NC heterostructures with size-controlled Ru cores encapsulated in N-doped graphene layers.Among these,Ru@NC-3h,with the best holistic effects,has superior durability and mass activity 7.03 times that of Pt/C.This high performance is attributed to the open porous structure,which enhances active site exposure and mass transfer,and the optimized adsorption and desorption of reaction intermediates by the strengthened heterointerfacial interaction between the smaller Ru cores and thin N-doped shells.Attenuated total reflectance surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)reveals reinforced interfacial water interaction and reduced hydrogen adsorption.Density functional theory(DFT)calculations indicate that the size effect promotes interfacial H_(2)O adsorption,whereas the electronic effect governs ^(*)H adsorption to collectively accelerate the HER kinetics.This novel strategy,introduced to regulate heterostructures through size and electronic effects,offers significant potential for various energy material applications.
基金supported by the National Key Research&Development Projects of China(Grant No.2022YFA1204100)National Natural Science Foundation of China(Grant No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(YSBR-003)the Innovation Program of Quantum Science and Technology(2021ZD0302700)。
文摘As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.
基金supported by the National Key Research and Development Program of China(No.2021YFB3801200)the National Natural Science Foundation of China(Nos.22278051,22178044,and 22308043)the Science and Technology Innovation foundation of CNPC(No.2022DQ02–0608).
文摘The imperative quest for renewable energy sources and advanced energy storage technologies has arisen amidst the escalating perils of climate change and dwindling fossil fuel reserves.In the realm of energy storage technologies,asymmetric supercapacitor(ASC)has garnered significant attention owing to its high energy density and power density.In the quest for advanced electrode materials for ASC,the integration of 2D layered heterostructures on hierarchical porous carbon(HPC)substrates has emerged as a promising approach to enhance the electrochemical performance.Herein,a highly innovative hierarchical NiCo LDH/MoS_(2)/HPC heterostructure was successfully synthesized using a simple two-step hydrothermal method for the electrode materials of ASC.Benefiting from the unique hierarchical heterostructure of NiCo LDH/MoS_(2)/HPC composite and the synergistic effect between the components,it reveals an exceptional specific capacitance of 2368 F/g at 0.5 A/g in a three-electrode system,which significantly exceeds that of conventional supercapacitor electrodes.Additionally,the ASC device of NiCo LDH/MoS_(2)/HPC//HPC achieves remarkable specific capacitance of 236 F/g at 0.5 A/g and an impressive energy density of 84Wh/kg at a power density of 400 W/kg,as well as superior cyclic stability.This study not only demonstrates the effectiveness of incorporating MoS_(2) and NiCo LDH into a carbon-based framework for supercapacitor applications but also opens avenues for designing more efficient energy storage devices.
基金supported by the National Natural Science Foundation of China(Nos.22271178,22301239)Science and Technology New Star in Shaanxi Province(No.2023KJXX-045)+3 种基金the Youth Talent Promotion Project of Science and Technology Association of Universities of Shaanxi Province(No.20240601)Shaanxi Provincial Department of Education service local special project,industrialization cultivation project(No.23JC007)the Research Program of the Shaanxi Provincial Department of Education(Nos.23JK0596,23JP135)the Open Foundation of Xi’an Key Laboratory of Functional Supramolecular Structure and Materials(No.CFZKFKT23003).
文摘The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromagnetic waves(EMW).Herein,a rational and universally applicable two-step hydrothermal method strategy was proposed to effectively control the electronic structure of Mott-Schottky EMW absorbing materials derived from Co-MOF.The as-synthesized Co_(3)S_(4)@MoS_(2)/NC ensures efficient electron transfer,while the change redistribution leads to the emergence of additional electric dipoles under an external EMM field.In addition,the hierarchical Co_(3)S_(4)@MoS_(2)/NC nano-architecture with a hierarchical arrange-ment in 2D and 3D offers more polarization sites,thereby extending the path for EMW transmission through multiple reflections and scattering.The potential to enhance the EMW absorption performance of Co_(3)S_(4)@MoS_(2)/NC lies in its unique microstructure and substantial surface area,which optimize impedance matching properties through a synergistic effect of dipole and interfacial polarization induced by Mott-Schottky heterointerfaces.As anticipated,the Co_(3)S_(4)@MoS_(2)/NC exhibits a maximum EMW absorption ca-pacity with an RLmin value of-41.97 dB and a broad EAB of 4.24 GHz at a thickness of 2.0 mm.This study provides insights for designing highly efficient Mott-Schottky EMW absorbing materials at the molecular level rationally.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFA1204000)partly by the National Natural Science Foundation of China (Grant Nos.12274405,12304155,and 12393831)the Beijing Natural Science Foundation (Grant No.Z230006)。
文摘Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching angle shift”, where the applied direct current is assumed to shift, via domain wall depinning during anti-domain expansion, the switching angle of a perpendicular magnetization in a linear proportional manner under a large rotating magnetic field. Here, we report that, for the most commonly employed perpendicular magnetization heterostructures in spintronics(e.g., those based on FeCoB, Co, and Co/Ni multilayers), the switching angle shift considerably misestimates the SOT within the domain wall depinning analysis of the slope of linear-in-current scaling and may also have a non-zero residual value at zero direct current. Our experiments and simulations unveil that the switching angle shift is most likely dominated by chiral asymmetric nucleation rather than expansion of anti-domains. The in-plane field from external magnets and current-induced SOTs lowers the perpendicular nucleation field and thus reduces the required switching angle, ultimately leading to an underestimation of SOTs by domain wall depinning analysis. These results have advanced our understanding of magnetization switching in spintronic devices.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3604203)the Key Research and Development Program of Guangdong Province,China(Grant No.2024B0101060002)the Key Research and Development Program of Shenzhen City,China(Grant No.JCYJ20241202130036043)。
文摘Research on p-channel field-effect transistors(p-FETs)remains limited,primarily due to the significantly lower conductivity of the two-dimensional hole gas(2DHG)compared to the two-dimensional electron gas(2DEG)in n-channel field-effect transistors(n-FETs),which poses a significant challenge for monolithic integration.In this study,we investigate the impact of epitaxial structure parameters on 2DHG properties in p-Ga N/Al Ga N/Ga N heterostructures through semiconductor technology computer-aided design(TCAD)simulations and theoretical calculations,identifying the conditions necessary to achieve high-density 2DHG.Our simulations demonstrate that increasing the p-Ga N thickness leads to two critical thicknesses determined by surface states and acceptor ionization concentration:one corresponds to the onset of 2DHG formation,and the other to its saturation.Lowering the donor surface state energy level and increasing the acceptor ionization concentration promote 2DHG formation and saturation,although the saturated density remains independent of surface states.Additionally,a higher Al composition enhances intrinsic ionization due to stronger polarization effects,thereby increasing the 2DHG sheet density.Consequently,to achieve high-density 2DHG in p-Ga N/Al Ga N/Ga N heterostructures,it is essential to increase the Al composition,ensure that the p-Ga N thickness exceeds the critical thickness for 2DHG saturation,and maximize the acceptor ionization concentration.This study elucidates the impact of epitaxial structure parameters on 2DHG properties in p-Ga N/Al Ga N/Ga N heterostructures and provides valuable guidance for the optimization of p-FET designs.
基金financially supported by the Natural Science Foundation of China(NSFC,No.22165032)Beijing Natural Science Foundation(No.2242032)
文摘The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-like Bi_(2)Fe_(4)O_(9)@Polypyrrole(BFO@PPy)heterostructure was successfully designed and fabricated using an efficient microwave hydrothermal method and an in situ polymerization process.Specifically,Bi_(2)Fe_(4)O_(9)enhances the chemical activity of ammonium persulfate,which in turn initiates the polymerization of pyrrole monomers,resulting in the formation of BFO@PPy heterostructures.The thickness of the PPy coating layer in the BFO@PPy composite can be precisely controlled at the nanoscale,optimizing electromagnetic parameters,conduction losses and interface polarization loss.The fabricated BFO@PPy composite achieves a minimum reflection loss(RL_(min))of-57.8 dB at a thickness of 2.5 mm and an effective absorption bandwidth(EAB)of 6.96 GHz.Furthermore,the EMW absorption performance and mechanism were systematically validated through theoretical calculations,radar cross-sectional simulations(RCS),and first-principles analysis.Notably,the RCS simulation of a 1:1 scale F-22 Raptor fighter model provides a realistic evaluation of the composite's EMW absorption potential in military applications.The efficient fabrication method and superior electromagnetic absorption performance make BFO@PPy a promising candidate for use in complex electromagnetic environments and military domains.Additionally,the BFO@PPy composite exhibits rapid electrothermal conversion at a low voltage(3V),achieving active infrared camouflage within a controllable temperature range,further highlighting its multifunctional properties.
基金the College Students Innovative Practice Fund of Jiangsu University Industrial Center(ZXJG2023047)for funding this research.
文摘Structured design helps to play out the coordination advantage and optimize the performance of electro-chemical reactions.In this work,hierarchical hollow microspheres(Co_(3)S_(4)@NiCo_(2)S_(4)) with unique core-shell heterostructure were successfully prepared through simple template and solvothermal methods.Thanks to the hollow structure,cross-linked nanowire arrays,and in-situ coating of zeolite imidazole framework(ZIF),Co_(3)S_(4)@NiCo_(2)S_(4) demonstrated excellent electrochemical performance with a specific ca-pacitance of up to 2697.7 F g^(-1)at 1 A g^(-1) and cycling stability of 80.5% after 5000 cycles.The covalent organic framework(COF)derived nano carbon,which had undergone secondary calcination and ZnCl_(2) activation,also exhibited excellent double-layer energy storage performance.Compared to a single calci-nation,the incredible increase in capacitance was up to 208.5 times greater,reaching 291.9 F g^(-1)at 1 A g^(-1)while maintaining ultra-high rate performance(81.0%at 20 A g^(-1)).The hybrid supercapacitor,assem-bled with Co_(3)S_(4)@NiCo_(2)S_(4)as the cathode and COF-derived carbon as the anode,exhibited an extremely high energy density(79.7 Wh kg^(-1)at 693.5 W kg^(-1))and excellent cyclic stability(maintained 79.3%after 10,000 cycles of 20 A g^(-1)),further explaining the reliable and practical characteristics.This work provided reference for the structural optimization of transition metal sulfides and the high-temperature activation of COF-derived carbon.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_0120)the National Natural Science Foundation of China(Nos.22275088 and 52101260)+3 种基金the Project of Shuangchuang Scholar of Jiangsu Province(No.JSSCBS20210212)the Fundamental Research Funds for the Central Universities(No.30921011203)the Start-Up Grant(No.AE89991/340)from Nanjing University of Science and Technology,the Foundation of Jiangsu Educational Committee(No.22KJB310008)the Senior Talent Program of Jiangsu University(No.20JDG073).
文摘The reduction of global carbon emissions and the achievement of carbon neutrality have become the focus of addressing climate change and global warming.Electrochemical CO_(2) reduction(CO_(2)RR),as a technology that can efficiently convert CO_(2) into value-added products,is receiving widespread attention.This article reviews the current research status of Cu/metal oxide heterostructures in the field of electrochemical reduction of CO_(2).The review first introduces the importance of electrochemical reduction of CO_(2) and the application potential of Cu/metal oxide heterostructures in this field.Subsequently,a comprehensive discussion is presented on the exploration of various Cu/metal oxide heterostructures and their corresponding structure-performance relationship,with particular emphasis on the catalysts'activity,selectivity,stability and the nature of active sites.Lastly,the review provides an overview of the current research challenges and future development trends in this field.
基金supported by the National Natural Science Foundation of China (No. 22305210, 52371238 to C. D.)the Shandong Provincial Natural Science Foundation (No. ZR2020QB108)+1 种基金the Graduate Innovation Foundation of Yantai University (GIFYTU)the Shandong Laboratory of Advanced Materials and Green Manufacturing (Yantai, AMGM2024A01)
文摘Heterogeneous structure and carbon coating are important ways to enhance the reaction kinetics and cycling stability of metal phosphides as anode materials for sodium-ion batteries.Therefore,nitrogen-doped carbon-capped triphasic heterostructure Cu_(3)P/Co_(2)P/CoP@NC stands for nitrogen doped carbon nanorods were designed and synthesized through a combination of phosphide and carbonization.Kinetic analyses(cyclic voltammetry,electrochemical impedance spectroscopy,and galvanostatic intermittent titration technique)and density functional theory calculations show that the three-phase heterostructure and carbon layer effectively improve Na adsorption and migration as well as the electrochemical reactivity of the electrode.Based on this,Cu_(3)P/Co_(2)P/CoP@NC demonstrated excellent rate performance(305.9 mAh g^(-1)at 0.3 A g^(-1)and 202.8 mAh g^(-1)even at 10 A g^(-1))and cycling stability(the capacity decay rate is only 0.12%from the 5th to 300th cycle)when it is used for sodium-ion battery anodes.The in situ X-ray diffraction,ex situ X-ray photoelectron spectroscopy,and high-resolution transmission electron microscopy tests showed that Cu_(3)P/Co_(2)P/CoP@NC is based on a conversion reaction mechanism for sodium-ion storage.In addition,the NVP@reduced graphene oxide(rGO)//Cu_(3)P/Co_(2)P/CoP@NC full-cell delivers a high capacity of 210.2 mAh g^(-1)after 50 cycles at 0.3 A g^(-1).This work can provide a reference for the design of high-performance sodium electrode anode materials.
基金Project supported by the National Natural Science Foundation of China (Grant No. 92477205)。
文摘Controlling charge polarity in the semiconducting single-walled carbon nanotubes(CNTs) by substitutional doping is a difficult work due to their extremely strong C–C bonding. In this work, an inner doping strategy is explored by filling CNTs with one-dimensional(1D)-TM_(6)Te_(6) nanowires to form TM_(6)Te_(6)@CNT-(16,0) 1D van der Waals heterostructures(1D-vd WHs). The systematic first-principles studies on the electronic properties of 1D-vd WHs show that N-type doping CNTs can be formed by charge transfer from TM_(6)Te_(6) nanowires to CNTs, without introducing additional carrier scattering.Particularly, contribution from both T M(e.g., Sc and Y) and Te atoms strengthens the charge transfer. The outside CNTs further confine the dispersion of Te-p orbitals in nanowires that deforms the C-π states at the bottom of the conduction band to quasi sp^(3) hybridization. Our study provides an inner doping strategy that can effectively confine the charge polarity of CNTs and further broaden its applications in some novel nano-devices.
基金Project supported by the National Key Research and Development Program of China(Grant No.2023YFF0719200)the National Natural Science Foundation of China(Grant Nos.62322115,U24A20226,61988102,and 62435010)+1 种基金the 111 Project(Grant No.D18014)the Science and Technology Commission of Shanghai Municipality(Grant Nos.22JC1400200 and 21S31907400)。
文摘The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectroscopy to investigate ultrafast electron transport properties in both van der Waals Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)ferromagnetic/topological heterostructures.Our results show that these heterostructures exhibit effective THz electromagnetic shielding.The complex conductivity spectra of Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)heterostructures with varying Fe_(4)GeTe_(2)thicknesses are analyzed using the Drude-Smith model.We quantitatively examine how Fe_(4)GeTe_(2)layer thickness affects the direct current conductivity,plasma frequency,carrier momentum scattering time,and back-scattering coefficient.As the number of Fe_(4)GeTe_(2)layers increases,intra-layer back-scattering events for charge carriers become more frequent.This work provides THz frequency spectra for both Fe_(4)GeTe_(2)and Bi_(2)Te_(3)/Fe_(4)GeTe_(2),aiding in the design and optimization of THz modulators and detectors.
