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Heterostructure design has been recognized as a promising strategy to reinforce the dielectric polarization response through the strengthened heterogeneous interface interaction. However, the controllable preparation of homogeneously distributed heterostructures in absorbers remains a great challenge. Herein, we proposed a moderate reduction strategy to synthesize a NiO/Ni heterostructure tightly embedded in MoO3–x nanorods in situ by controlling phase evolution of NiO to metallic Ni under the H2/Ar atmosphere. Profiting from the abundant NiO/Ni heterostructures that induced electron migration and redistribution at NiO/Ni interfaces, the NiO/Ni/MoO3–x absorbers show a strengthened interfacial polarization relaxation response. Enriched oxygen vacancies serve as dipole polarization centers to form independent electric dipole pairs, which are conductive to the enhancement of dipole polarization loss under the alternating electromagnetic filed. Additionally, the homogeneously distributed magnetic Ni species construct a magnetic coupling network and generate ferromagnetic resonance and eddy current loss to boost magnetic loss. Consequently, the resultant absorbers display superior electromagnetic wave absorption performances with a minimum reflection loss value of −64.18 dB and maximum absorption bandwidth up to 6.6 GHz with a thickness of 1.8 mm, effectively covering the whole Ku-band. The radar cross-section (RCS) simulations demonstrate the excellent radar signal suppression capability of NiO/Ni/MoO3–x absorbers and the maximum RCS reduction value reaching 21.3 dB at 0°. The obtained absorption properties almost surpass most of the reported composites with embedded heterostructures. This work provides a strategy for the preparation of multiple heterogeneous interfaces and presents a deep insight into the attenuation mechanisms of absorbers. [ABSTRACT FROM AUTHOR]

Precise control over the composition of heterostructure nanocrystals and their self-assembly is an emerging research interest. Superstructures of this type are typically enhanced in terms of their collective functionalities. Herein, we developed a practical yet simple approach to synthesize and self-assemble Cu2–xS/CuYS (Y = In, Sb, and Sn) heterostructured nanorods (NRs) into their vertically standing up assemblies. First NRs come together via depletion–attraction forces, and then partial cation exchange between Cu31S16 NRs and the injected cationic precursor taken in stoichiometric amounts dissolved in trioctylphosphine and oleylamine (Olam) results in heterostructured NRs possessing compositions of Cu2–xS/CuYS (Y = In, Sb, and Sn). The chemical composition changes lead to surface chemistry modifications as the injected guest cationic part of the NR is either naked or covered with Olam which is quite easy to strip-off from the NC surface at high temperature, resulting in a 2D sheetlike structure of heterostructured vertically oriented NRs in solution. The route to obtaining long-range heterostructured assembled NRs is studied and characterized systematically. This work presents a detailed mechanistic insight into the cation exchange-induced self-assembly of heterostructured NRs, where the particles are coupled, which is of growing importance as a synthesis tool. The complex nanostructures synthesized in the present work may benefit solution-processed optoelectronic applications. [ABSTRACT FROM AUTHOR]

Temperature field engineering provides a robust framework for investigating the behavior of phonons and excitons within two-dimensional (2D) layered van der Waals materials. Herein, we measured the photoluminescence (PL) spectroscopy of few-layer WSe2 and WSe2/graphene van der Waals heterostructures at various temperatures (from 10 to 300 K). The results indicate that the PL intensity of the heterostructure is lower than that of few-layer WSe2, which is attributed to charge transfer at the interface under photoexcitation conditions. The PL spectroscopy spectrum of the heterostructure is primarily composed of four distinct spectral features, arising from distinct phonon-assisted processes, direct recombination, and excitonic contributions. Furthermore, these physical processes can be modulated by varying the temperature. For instance, the phonon-assisted PL process gradually diminishes with the decrease in temperature, whereas the excitonic PL process emerges more distinctly with the reduction in temperature. These findings can provide support for understanding the photophysical processes in 2D heterostructure materials and lay the groundwork for optoelectronic devices based on nanomaterials. [ABSTRACT FROM AUTHOR]

The suppression of quantum efficiency of transition metal dichalcogenide (TMD) heterostructures (HS) with type II band alignment leads to severe restriction of integration-based optoelectronic and photovoltaic application development. To address this issue, we have successfully adopted ozone intercalation to manage the photoluminescence (PL) emission efficiency in TMDs HS with a type II band alignment. By controlling the amount of ozone introduced, we can regulate the fluorescence from strong quenching to effective enhancement. We propose that the PL intensity modulation of the TMDs HS area, with 2 orders of magnitude of controllability, can be ascribed to the inhibitory effect of ozone on the formation of interlayer excitons and the combination of charge transfer between the materials. Furthermore, this manipulation method for HS has been proven to have a strong universality. Our findings pave a viable way for achieving quantum efficiency manipulation of HS integration-based optical devices with complete tunability, including wavelength-tunable light emitters. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) have garnered significant interest as promising candidates for nanoscale optoelectronic applications due to their excellent optical properties. Axially heterostructured CsPbBr3–CsPb-(Br(1–x)Clx)3 nanowires can be produced by localized anion exchange of pregrown CsPbBr3 nanowires. However, characterizing such heterostructures with sufficient strain and real space resolution is challenging. Here, we use nanofocused scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with a 60 nm beam to investigate a heterostructured MHP nanowire as well as a reference CsPbBr3 nanowire. The nano-XRD approach gives spatially resolved maps of composition, lattice spacing, and lattice tilt. Both the reference and exchanged nanowire show signs of diverse types of ferroelastic domains, as revealed by the tilt maps. The chlorinated segment shows an average Cl composition of x = 66 and x = 70% as measured by XRD and XRF, respectively. The XRD measurements give a much more consistent result than the XRF ones. These findings are consistent with photoluminescence measurements, showing x = 73%. The nominally unexchanged segment also has a small concentration of Cl, as observed with all three methods, which we attribute to diffusion after processing. These results highlight the need to prevent such unwanted processes in order to fabricate optoelectronic devices based on MHP heterostructures. [ABSTRACT FROM AUTHOR]

The directional modulation of metal oxide semiconductors (MOSs) can be effective in developing high-performance gas-sensing materials. Herein, we propose an efficient strategy by modifying ZnWO4 on In2O3 to achieve controllable modulation of oxygen vacancies and energy band structures in ZnWO4/In2O3 heterostructures. The sensor based on optimized ZnWO4/In2O3 exhibits significantly enhanced performance to detect triethylamine, including a lower operating temperature (100 °C), a higher responsivity (Ra/Rg = 221.2 for 100 ppm), and a lower detection limit (500 ppb). In addition, the fabricated sensor exhibits faster response and good selectivity. The improved gas-sensing performance could be attributed to the acid–base interaction between triethylamine gas and ZnWO4, the formation of heterojunctions, and the increase of oxygen vacancies to achieve a synergistic modulation of the chemical and energy band structures. It is anticipated that our current investigation could offer insights and a useful strategy for triethylamine detection. [ABSTRACT FROM AUTHOR]

Black phosphorus (BP), a two-dimensional (2D) van der Waals (vdW)-layered nanomaterial, has attracted explosive study due to the rediscovery of its 2D counterparts (phosphorene) in 2014. Because of its unique structures, superior electrical and optoelectronic capabilities, and compatibility with silicon-based technologies, it is considered a viable material for high-performance photodetection. Controlled ways for the scalable synthesis of good quality large-sized BP are sought to achieve these wonderful expectations, but perfect methodologies are currently lacking. Meanwhile, cutting-edge research shows that the instability of BP under ambient conditions poses a substantial difficulty in a variety of applications. Here, not only an extensive overview of preparation methods but also a summary of the passivation strategy, photoelectric application, and challenges of BP are provided. [ABSTRACT FROM AUTHOR]

Herein, a multistep synthesis method was implemented to prepare nanoscale core@shell spherical heterostructures for H2 optical detection. The resulting nanoheterostructures are built with gold cores and silica shells further coated by a thin layer of spherical palladium nanoparticles. Samples with various thicknesses of silica and densities of palladium nanoparticles were synthesized and characterized by transmission electron microscopy. In particular, the three-dimensional core@shell configuration was confirmed by electron tomography. The optical properties of the obtained nanostructures were first analyzed by optical absorbance measurements, and their potential use for H2 detection was evaluated by simulations based on the discrete dipole approximation method. Thus, the optical response of the studied nanostructures is investigated theoretically when the Pd layer is hydrogenated, showing the great sensitivity achievable with these nanostructures. [ABSTRACT FROM AUTHOR]

We designed and prepared the ZnSe/CoSe 2 @NC/CNTs (ZCNC) cathode material for aluminum batteries (ABs). The ZCN (ZnSe/CoSe 2 @NC) is connected by the interwoven carbon nanotube (CNT) conductive network to form a beaded structure. CNTs and the carbon formed by carbonization of organic ligands is beneficial to improving the electrical conductivity of the material and reducing structural damage during cycling. The internal electric field generated at the interface of heterostructures can promote the transfer of electrons/ions. This special structure promotes ZCNC excellent electrochemical properties. At 100 mA/g, the specific capacity of the first discharge reaches 338 mAh/g, while the specific capacity after 500 cycles still reaches 217 mAh/g. Compared with ZCN and CN(CoSe 2 @NC), it demonstrates a great advantage.

Continuous monitoring of ammonia (NH 3 ) in humid environments poses a notable challenge for gas sensing applications because of its effect on sensor sensitivity. The present work investigates the detection of NH 3 in a natural humid environment utilizing ReS 2 /Ti 3 C 2 T x heterostructures as a sensing platform. ReS 2 nanosheets were vertically grown on the surface of Ti 3 C 2 T x sheets through a hydrothermal synthetic approach, resulting in the formation of ReS 2 /Ti 3 C 2 T x heterostructures. The structural, morphological, and optical properties of ReS 2 /Ti 3 C 2 T x were investigated using various state-of-the-art techniques, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, zeta potential, Brunauer-Emmett-Teller technique, and Raman spectroscopy. The heterostructures exhibited 1.3- and 8-fold increases in specific surface area compared with ReS 2 and Ti 3 C 2 T x , respectively, potentially enhancing the active gas adsorption sites. The electrical investigations of the ReS 2 /Ti 3 C 2 T x -based sensor demonstrated enhanced selectivity and superior sensing response ranging from 7.8 to 12.4% toward 10 ppm of NH 3 within a relative humidity range of 15-85% at room temperature. These findings highlight the synergistic effect of ReS 2 and Ti 3 C 2 T x , offering valuable insights for NH 3 sensing in environments with high humidity, and are explained in the gas sensing mechanism.

Helicity-resolved Raman spectra can provide an intricate view into lattice structural details. Through the analysis of peak positions, intensities, and circular polarized Raman signals, a wealth of information about chiral structure arrangement within the moiré superlattice, interlayer interaction strength, polarizability change in chemical bond, and beyond can be unveiled. However, the relationship between the circular polarization of high-frequency Raman and twist angle is still not clear. Here, we utilize helicity-resolved Raman spectroscopy to explore the interlayer interactions and the effect of the moiré superlattice in WS 2 /WSe 2 heterostructures. For the out-of-plane Raman mode A 1g of WS 2 (A 1g and 1 E 2g of WSe 2 ), its intensity is significantly enhanced (suppressed) in WS 2 /WSe 2 heterostructures when θ is less than 10° or greater than 50°. This observation could be attributed to the large polarizability changes in both W-S and W-Se covalent bonds. The circular polarization of 2LA(M) in WSe 2 of the WS 2 /WSe 2 heterostructure (θ < 10° or θ > 50°) is significantly enhanced compared to that of 2LA(M) in the monolayer WSe 2 . We deduce that the circular polarization of the Raman mode correlates with the proportion of high-symmetry area within a supercell of the moiré lattice. Our findings improve the understanding of twist-angle-modulated Raman modes in TMD heterostructures.

Trapped materials at the interfaces of two-dimensional heterostructures (HS) lead to reduced coupling between the layers, resulting in degraded optoelectronic performance and device variability. Further, nanobubbles can form at the interface during transfer or after annealing. The question of what is inside a nanobubble, i.e., the trapped material, remains unanswered, limiting the studies and applications of these nanobubble systems. In this work, we report two key advances. First, we quantify the interface quality using RAW format optical imaging (unprocessed image data) and distinguish between ideal and non-ideal interfaces. The HS/substrate ratio value is calculated using a transfer matrix model and is able to detect the presence of trapped layers. The second key advance is the identification of water as the trapped material inside a nanobubble. To the best of our knowledge, this is the first study to show that optical imaging alone can quantify interface quality and find the type of trapped material inside spontaneously formed nanobubbles. We also define a quality index parameter to quantify the interface quality of HS. Quantitative measurement of the interface will help answer the question whether annealing is necessary during HS preparation and will enable creation of complex HS with small twist angles. Identification of the trapped materials will pave the way toward using nanobubbles for optical and engineering applications.

Insufficient angiogenic stimulation and dysregulated glycolipid metabolism in senescent vascular endothelial cells (VECs) constitute crucial features of vascular aging. Concomitantly, the generation of excess senescence-associated secretory phenotype (SASP) and active immune-inflammatory responses propagates within injured vessels, tissues, and organs. Until now, targeted therapies that efficiently rectify phenotypic abnormalities in senescent VECs have still been lacking. Here, we constructed a Pd/ h CeO 2 -BMS309403@platelet membrane (PCBP) nanoheterostructured capsule system loaded with fatty acid-binding protein 4 (FABP4) inhibitors and modified with platelet membranes and investigated its therapeutic role in aged mice. PCBP showed significant maintenance in aged organs and demonstrated excellent biocompatibility. Through cyclic tail vein administration, PCBP extended the lifespan and steadily ameliorated abnormal phenotypes in aged mice, including SASP production, immune and inflammatory status, and age-related metabolic disorders. In senescent ECs, PCBP mediated the activation of vascular endothelial growth factor (VEGF) signaling and glycolysis and inhibition of FABP4 by inducing the synthesis of hypoxia-inducible factor-1α, thereby reawakening neovascularization and restoring glycolipid metabolic homeostasis. In conclusion, the PCBP nanocapsule system provides a promising avenue for interventions against aging-induced dysfunction.

As semiconductor devices approach dimensions at the atomic scale, controlling the compositional grading across heterointerfaces becomes paramount. Particularly in nanowire axial heterostructures, which are promising for a broad spectrum of nanotechnology applications, the achievement of sharp heterointerfaces has been challenging owing to peculiarities of the commonly used vapor-liquid-solid growth mode. Here, the grading of Al across GaAs/Al x Ga 1- x As/GaAs heterostructures in self-catalyzed nanowires is studied, aiming at finding the limits of the interfacial sharpness for this technologically versatile material system. A pulsed growth mode ensures precise control of the growth mechanisms even at low temperatures, while a semiempirical thermodynamic model is derived to fit the experimental Al-content profiles and quantitatively describe the dependences of the interfacial sharpness on the growth temperature, the nanowire radius, and the Al content. Finally, symmetrical Al profiles with interfacial widths of 2-3 atomic planes, at the limit of the measurement accuracy, are obtained, outperforming even equivalent thin-film heterostructures. The proposed method enables the development of advanced heterostructure schemes for a more effective utilization of the nanowire platform; moreover, it is considered expandable to other material systems and nanostructure types.

The generation of hydrogen through photocatalysis is a fascinating technology for addressing environmental concerns and the energy crisis. Nevertheless, the quest for cost-effective, stable, and efficient photocatalysts in the realm of energy conversion remains a significant challenge. Herein, we designed novel InVO 4 /Ti 3 C 2 MXene (IVTC) heterostructures by employing acid etching to produce Ti 3 C 2 MXene with an accordion-like morphology, using the hydrothermal technique for the production of orthorhombic InVO 4 nanoparticles (NPs), and integrating them through a self-assembly approach. Both field-emission scanning electron microscopy and HRTEM analyses revealed a consistent distribution of InVO 4 NPs with an average size of 43.4 nm on both surfaces and between the sheets of Ti 3 C 2 MXene. The intimate interface between the Ti 3 C 2 MXene nanosheet and InVO 4 suppressed carrier recombination and promoted charge transfer, thereby boosting photocatalytic H 2 production. Under visible light exposure, the rate of hydrogen evolution is enhanced in IVTC heterostructures containing an optimized 10% loading of InVO 4 , exhibiting over a 3-fold increase compared to pristine InVO 4 NPs, maintaining efficiency across four cycles. This research presents a promising method for designing and creating high-efficiency heterostructures possessing excellent visible-light-driven photocatalytic activity for H 2 evolution.

Glass ceramic (GC) is the most promising material for objective lenses for extreme ultraviolet lithography that must meet the subnanometer precision, which is characterized by low values of high spatial frequency surface roughness (HSFR). However, the HSFR of GC is typically degraded during ion beam figuring (IBF). Herein, a developed method for constructing molecular dynamics (MD) models of GC was presented, and the formation mechanisms of surface morphologies were investigated. The results indicated that the generation of the dot-like microstructure was the result of the difference in the erosion rate caused by the difference in the intrinsic properties between ceramic phases (CPs) and glass phases (GPs). Further, the difference in the microstructure of the IBF surface under different beam angles was mainly caused by the difference in the two types of sputtering. Quantum mechanical calculations showed that the presence of interstitial atoms would result in electron rearrangement and that the electron localization can lead to a reduction in CP stability. To obtain a homogeneous surface, the effects of beam parameters on the heterogeneous surface were systematically investigated based on the proposed MD model. Then, a novel ion beam modification (IBM) method was proposed and demonstrated by TEM and GIXRD. The range of ion beam smoothing parameters that could effectively converge the HSFR of the modified surface was determined through numerous experiments. Using the optimized beam parameters, an ultrathin homogeneous modified surface within 3 nm was obtained. The HSFR of GC smoothed by ion beam modification-assisted smoothing (IBMS) dropped from 0.348 to 0.090 nm, a 74% reduction. These research results offer a deeper understanding of the morphology formation mechanisms of the GC surfaces involved in ion beam processing and may point to a new approach for achieving ultrasmooth heterostructure surfaces down to the subnanometer scale.

Manipulation of excitonic emission in two-dimensional (2D) materials via the assembly of van der Waals (vdW) heterostructures unlocks numerous opportunities for engineering their photonic and optoelectronic properties. In this work, we introduce a category of mixed-dimensional vdW heterostructures, integrating 2D materials with one-dimensional (1D) semiconductor nanowires composed of vdW layers. This configuration induces spatially distinct localized excitonic emissions through a tailored interfacial heterolayer atomic arrangement. By precisely adjusting both the axial and sidewall facet orientations of bottom-up grown PbI 2 vdW nanowires and by transferring them onto 1L WSe 2 flakes, we establish vdW heterointerfaces with either perpendicular or parallel interatomic arrangements. The edge-standing heterojunction, featuring perpendicular PbI 2 layers atop WSe 2 , promotes efficient charge transfer through the edges and coupled localized states, leading to an enhanced redshifted excitonic emission. Conversely, the layer-by-layer heterointerface, where PbI 2 layers are in parallel contact with WSe 2 , exhibits substantial quenching due to deep midgap states in a type-II alignment, as evidenced by power-dependent measurements and first-principle calculations. Our results introduce a method for actively manipulating excitonic emissions in 2D transition metal dichalcogenides (TMDs) through edge engineering, highlighting their potential in the development of various quantum devices.

Photocatalysis, a promising solution to environmental challenges, relies on the generation and utilization of photogenerated charge carriers within photocatalysts. However, the recombination of these carriers often limits efficiency. Heterostructures, especially Cu 2 O/TiO 2 , have emerged as effective solutions to enhance charge separation. This study systematically explores the effect of interfacial morphologies on the band bending within Cu 2 O/TiO 2 anatase heterostructures by employing density functional theory. Through this study, eight distinct interfaces are identified and analyzed, revealing a consistent staggered-type band alignment. Despite variations in band edge positions, systematic charge transfer from Cu 2 O to TiO 2 is observed across all interfaces. The proposed band bending configurations would suggest enhanced charge separation and photocatalytic activity under ultraviolet illumination due to a Z -scheme configuration. This theoretical investigation provides valuable insights into the interplay between interfacial morphology, band bending, and charge transfer for advancing the understanding of fundamental electronic mechanisms in heterostructures.

Titanium trisulfide (TiS 3 ) nanoribbons, when coated with titanium dioxide (TiO 2 ), can be used for water splitting in the KOH electrolyte. TiO 2 shells can be prepared through thermal annealing to regulate the response of TiS 3 /TiO 2 heterostructures by controlling the oxidation time and growth atmosphere. The thickness and structure of the TiO 2 layers significantly influence the photoelectrocatalytic properties of the TiS 3 /TiO 2 photoanodes, with amorphous layers showing better performance than crystalline ones. The oxide layers should be thin enough to transfer photogenerated charge through the electrode-electrolyte interface while protecting TiS 3 from KOH corrosion. Finally, the performance of TiS 3 /TiO 2 heterostructures has been improved by coating them with various electrocatalysts, NiS x being the most effective. This research presents new opportunities to create efficient semiconductor heterostructures to be used as photoanodes in corrosive alkaline aqueous solutions.

The construction of low-cost electrocatalysts with good conductivity, excellent intrinsic activity, and superior stability is crucial for the hydrogen evolution reaction (HER). Herein, we report an outstanding catalyst (Ni0.2Mo0.8N/NiMoP2/MoO2@NC) consisting of NiMo-based nanorod arrays supported on Ni foams for the efficient alkaline HER. It shows an ultralow overpotential of 48 mV and remarkable longevity for over 145 h at 10 mA cm–2 in 1.0 M KOH. The integration of ample compositions is favorable to the formation of heterointerfaces, accelerating electron transfer. The assembly of transition metal nitrides and phosphides fully develops the electrical conductivity of metal materials, which paves the way for superstability. The superior electrocatalytic activities can be attributed to the vital features, including the synergistic effect of Ni0.2Mo0.8N and NiMoP2, good electrical conductivity of MoO2, and corrosion resistance of NC basement. The present work proposes that regulating compositions and hierarchical nanostructures are of significance in developing electrode materials for the HER. [ABSTRACT FROM AUTHOR]

Designing heterostructure materials at the nanoscale is a well-known method to enhance gas sensing performance. In this study, a mixed solution of zinc chloride and tin (II) chloride dihydrate, dissolved in ethanol solvent, was used as the initial precursor for depositing the sensing layer on alumina substrates using the ultrasonic spray pyrolysis (USP) method. Several ZnO/SnO2 heterostructures were grown by applying different ratios in the initial precursors. These heterostructures were used as active materials for the sensing of H2S gas molecules. The results revealed that an increase in the zinc chloride in the USP precursor alters the H2S sensitivity of the sensor. The optimal working temperature was found to be 450 °C. The sensor, containing 5:1 (ZnCl2: SnCl2·2H2O) ratio in the USP precursor, demonstrates a higher response than the pure SnO2 (∼95 times) sample and other heterostructures. Later, the selectivity of the ZnO/SnO2 heterostructures toward 5 ppm NO2, 200 ppm methanol, and 100 ppm of CH4, acetone, and ethanol was also examined. The gas sensing mechanism of the ZnO/SnO2 was analyzed and the remarkably enhanced gas-sensing performance was mainly attributed to the heterostructure formation between ZnO and SnO2. The synthesized materials were also analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and X-ray photoelectron spectra to investigate the material distribution, grain size, and material quality of ZnO/SnO2 heterostructures. [ABSTRACT FROM AUTHOR]

Colloidal nanoplatelets (NPLs) have emerged as the last class of semiconductor nanocrystals for their potential optoelectronic applications. The heterostructures of these nanocrystals can achieve high photoluminescence quantum yield and enhanced photostability, along with color purity. Such advantages make them a promising candidate for solution-processable light-emitting diodes (LEDs). However, to date, blue-emitting CdSe nanoplatelets (NPLs) exhibit poor photoluminescence quantum yield and also typically suffer from a rolled-up morphology. To mitigate these problems in this work, we propose and demonstrate efficient alloyed 4 ML CdSe1–xSx nanoplatelets having a CdS crown with enhanced photoluminescence quantum yields (up to 60%) in the blue region (462–487 nm). We successfully used these NPLs as an electrically driven active emitter in the blue-emitting NPL-LEDs with a low turn-on voltage of ∼4 V. The Commission Internationale de L'Eclairage (CIE) coordinates of (0.23, 0.14) were obtained for these blue-emitting NPL-LEDs. These emitters could potentially open up the opportunity for full-color displays using these NPL-based blue LEDs in conjunction with the red and green ones. [ABSTRACT FROM AUTHOR]

Protein-mediated doping of ZnO with plasmonic nanoparticles offers control over surfaces, electronic states, carrier dynamics, and spectral fingerprints. Here, we report on ZnO-nano-Au bioinorganic heterostructures prepared using a chimeric polypeptide that combines most of the ZnO-binding sequence GLHVMHKVAPPR and the gold-binding AYSSGAPPMPPF sequence. The one-pot peptide-mediated synthesis was performed in the presence and absence of HAuCl4 to determine the impact of the peptide and metallic component on the structural and electronic properties of the ZnO assembly. Electron microscopy confirms that the chimera polypeptide promotes the synthesis of both spherical and nonspherical gold nanoparticles, which are properly embedded in ZnO. The optical absorption spectra describe a complex palette of plasmon modes, while the luminescence spectra show a dominant subset of near-infrared spectral fingerprints that suggest an increasing role of surfaces in carrier relaxation. Simulations using finite difference time-domain theory describe collective plasmon phenomena specific to gold nanoparticles embedded in ZnO. Furthermore, to confirm experimental data, theory suggests an interinclusion nanogold spacing of 10 nm or less. Flexibility of the primary sequence of the chimera in the synthesis of ZnO-nano-Au composites opens up possibilities for plasmon-modulated ZnO junctions with Ohmic contacts as sought in sensor technologies and for security applications. [ABSTRACT FROM AUTHOR]

Two-dimensional tungsten disulfide (WS2), as one of the widely concerned members of the transition metal dichalcogenides family, has been studied broadly by its outstanding photonic and electronic properties. Since all of the research works focus on size and the number of layers, the dendritic structure WS2 has been scarcely reported. In our study, we make use of atmospheric pressure chemical vapor deposition (APCVD) to control the synthesis of dendritic WS2/monolayer WS2 heterostructures on the SiO2/Si substrate. The stacking morphology of the heterostructure is verified by AFM, Raman, and PL spectra. The effects of growth times and carrier gas flux on the quasi-epitaxial growth of WS2 films with dendritic structures have been systematically studied. In addition, the transition between fractal, dendritic, and compact morphologies with the increase of the growth times (carrier gas flux) are more significant. The compact morphology and difference of contact potential between the adjacent dendritic structures are characterized by Kelvin probe force microscopy (KPFM). Moreover, the as-fabricated FET devices exhibit excellent electronic properties (on/off ratio, carrier mobility, photoresponsivity, and response time are about 106, 11.42 cm2 V–1S1–, 46.6 mA/W, and 105.5 μs, respectively). This study paves the way for the rational design of high-sensitivity fractal-enhanced phototransistor devices for industrial and commercial applications. [ABSTRACT FROM AUTHOR]

Understanding quantum transport through DNA-based heterostructures is a key to advancing the field of DNA nanoelectronics, where quantum interference would play a significant role. Electronic "barriers" and "wells" can be constructed in DNA using adenine–thymine (AT) and guanine–cytosine (GC) base pairs, respectively, as their ionization potentials differ significantly. We investigate the influence of the width of barriers and wells on hole transport. Density functional theory calculations are performed on energy-minimized DNA structures, followed by quantum transport calculations including decoherence. The device physics is probed by constructing a model Hamiltonian and selectively turning off long-range and interstrand interactions. Major outcomes of the study include the following: (1) DNA heterostructures complement the solid-state semiconductor counterparts; that is, conductance decreases sharply and marginally with an increase in barrier and well width, respectively; (2) quantum interference in DNA heterostructures is robust, as seen by clear peaks in the transmission resonance even with decoherence; (3) DNA conformation has a profound role in deciding the conductance of equivalent heterostructures; and (4) structural differences lead to closer HOMO energy levels and more delocalized states. As a result, transport can be efficient in some strands even with weaker π–π orbital overlap. [ABSTRACT FROM AUTHOR]

We examine the electronic structure of recently fabricated in-plane heterojunctions of zigzag graphene nanoribbons embedded in hexagonal boron nitride. We focus on hitherto unexplored interface configurations in which both edges of the nanoribbon are bonded to the same chemical species, either boron or nitrogen atoms. Using ab initio and mean-field Hubbard model calculations, we reveal the emergence of one-dimensional magnetic conducting channels at these interfaces. These channels originate from the energy shift of the magnetic interface states that is induced by charge transfer between the nanoribbon and hexagonal boron nitride. We further address the response of these heterojunctions to external electric and magnetic fields, demonstrating the tunability of energy and spin splittings in the electronic structure. Our findings establish that zigzag graphene nanoribbon/hexagonal boron nitride heterojunctions are a suitable platform for exploring and engineering spin transport in the atomically thin limit, with potential applications in integrated spintronic devices.

Engineering symmetry breaking in thermoelectric materials holds promise for achieving an optimal thermoelectric efficiency. van der Waals (vdW) layered transition metal dichalcogenides (TMDCs) provide critical opportunities for manipulating the intrinsic symmetry through in-plane symmetry breaking interlayer twists and out-of-plane symmetry breaking heterostructures. Herein, the symmetry-dependent thermoelectric properties of MoS 2 and MoSe 2 obtained via first-principles calculations are reported, yielding an advanced ZT of 2.96 at 700 K. The underlying mechanisms reveal that the in-plane symmetry breaking results in a lowest thermal conductivity of 1.96 W·m -1 ·K -1 . Additionally, the electric properties can be significantly modulated through band flattening and bandgap alteration, stemming directly from the modified interlayer electronic coupling strength owing to spatial repulsion effects. In addition, out-of-plane symmetry breaking induces band splitting, leading to a decrease in the degeneracy and complex band structures. Consequently, the power factor experiences a notable enhancement from ∼1.32 to 1.71 × 10 -2 W·m -1 ·K -2 , which is attributed to the intricate spatial configuration of charge densities and the resulting intensified intralayer electronic coupling. Upon simultaneous implementation of in-plane and out-of-plane symmetry breaking, the TMDCs exhibit an indirect bandgap to direct bandgap transition compared to the pristine structure. This work demonstrates an avenue for optimizing thermoelectric performance of TMDCs through the implementation of symmetry breaking.

Stimuli-responsive micro/nanoscale photonic barcodes show great capacity for encryption and anticounterfeiting technologies due to multiple authentications, yet their application is commonly restricted by invasive stimuli. Herein, we report noninvasive light-stimulated high-security photonic barcodes based on spatially assembled photoresponsive two-dimensional (2D) 1,3,5-benzenetribenzoate (BTB)@Ln-MOF host-guest heterostructures. The photoluminescence (PL) spectra information on BTB@Ln-MOF heterostructures could be precisely controlled by the different wavelengths of ultraviolet (UV) light trigger. By using the PL properties and 2D heterostructures as cryptographic primitives, spatially resolved smart photonic barcodes based on both spectral and graphical coding are realized in BTB@Ln-MOF host-guest materials. These results will pave an avenue for the development of smart stimuli-responsive photonic barcodes for anticounterfeiting applications.

Perovskites have great potential for optoelectronic applications due to their high photoluminescence quantum yield, large absorption coefficient, great defect tolerance, and adjustable band gap. Perovskite heterostructures may further enhance the performance of optoelectronic devices. So far, however, most of perovskite heterostructures are fabricated by mechanical stacking or spin coating, which could introduce a large number of defects or impurities at the heterointerface owing to the random stacking process. Herein, we report the epitaxial growth of CsPbBr 3 pyramids/CdS nanobelt heterostructures via a 2-step vapor deposition route. The CsPbBr 3 triangular pyramids are well aligned on the surface of CdS nanobelts with the epitaxial relationships of (0-22) CsPbBr 3 ||(1-20) CdS and (-211) CsPbBr 3 ||(002) CdS . Time-resolved photoluminescence results reveal that effective charge transfer occurred at the heterointerface, which can be attributed to the type-II band arrangement. Theoretical simulations reveal that the unique CsPbBr 3 pyramids/CdS nanobelt structure facilitates diminishing the reflection losses and enhancing the light absorption. The photodetector based on these CsPbBr 3 pyramids/CdS nanobelt heterostructures exhibited an ultrahigh photoswitching ratio of 2.14 × 10 5 , a high responsivity up to 4.07 × 10 4 A/W, a high detectivity reaching 1.36 × 10 13 Jones, fast photoresponses (τ rise = 472 μs and τ decay = 894 μs), low dark current, and suppressed hysteresis.

van der Waals heterostructures of two-dimensional materials have unveiled frontiers in condensed matter physics, unlocking unexplored possibilities in electronic and photonic device applications. However, the investigation of wide-gap, high-κ layered dielectrics for devices based on van der Waals structures has been relatively limited. In this work, we demonstrate an easily reproducible synthesis method for the rare-earth oxyhalide LaOBr, and we exfoliate it as a 2D layered material with a measured static dielectric constant of 9 and a wide bandgap of 5.3 eV. Furthermore, our research demonstrates that LaOBr can be used as a high-κ dielectric in van der Waals field-effect transistors with high performance and low interface defect concentrations. Additionally, it proves to be an attractive choice for electrical gating in excitonic devices based on 2D materials. Our work demonstrates the versatile realization and functionality of 2D systems with wide-gap and high-κ van der Waals dielectric environments.

The realization of sodium-ion devices with high-power density and long-cycle capability is challenging due to the difficulties of carrier diffusion and electrode fragmentation in transition metal selenide anodes. Herein, a Mo/W-based metal-organic framework is constructed by a one-step method through rational selection, after which MoWSe/C heterostructures with large angles are synthesized by a facile selenization/carbonization strategy. Through physical characterization and theoretical calculations, the synthesized MoWSe/C electrode delivers obvious structural advantages and excellent electrochemical performance in an ethylene glycol dimethyl ether electrolyte. Furthermore, the electrochemical vehicle mechanism of ions in the electrolyte is systematically revealed through comparative analyses. Resultantly, ether-based electrolytes advantageously construct stable solid electrolyte interfaces and avoid electrolyte decomposition. Based on the above benefits, the Na half-cell assembled with MoWSe/C electrodes demonstrated excellent rate capability and a high specific capacity of 347.3 mA h g -1 even after cycling 2000 cycles at 10 A g -1 . Meanwhile, the constructed sodium-ion capacitor maintains ∼80% capacity retention after 11,000 ultralong cycles at a high-power density of 3800 W kg -1 . The findings can broaden the mechanistic understanding of conversion anodes in different electrolytes and provide a reference for the structural design of anodes with high capacity, fast kinetics, and long-cycle stability.

Industrial emissions, environmental monitoring, and medical fields have put forward huge demands for high-performance and low power consumption sensors. Two-dimensional quasicrystal (2D QC) nanosheets of metallic multicomponent Al 70 Co 10 Fe 5 Ni 10 Cu 5 have emerged as a promising material for gas sensors due to their excellent catalytic and electronic properties. Herein, we demonstrate highly sensitive and selective NO 2 sensors developed by low-cost and scalable fabrication techniques using 2D QC nanosheets and α-Fe 2 O 3 nanoparticles. The sensitivity (Δ R / R %) of the optimal amount of 2D QC nanosheet-loaded α-Fe 2 O 3 sensor was 32%, which is significantly larger about 3.5 times than bare α-Fe 2 O 3 sensors for 1 ppm of NO 2 at 150 °C operating temperature. The sensors exhibited p-type conduction, and resistance was reduced when exposed to NO 2 , an oxidizing gas. The enhanced sensing characteristics are a result of the formation of nanoheterojunctions between 2D QC and α-Fe 2 O 3 , which improved the charge transport and provided a large sensing signal. In addition, the heterojunction sensor demonstrated excellent NO 2 selectivity over other oxidizing and reducing gases. Furthermore, density functional theory calculation examines the adsorption energy and charge transfer between NO 2 molecules on the α-Fe 2 O 3 (110) and QC/α-Fe 2 O 3 (110) heterostructure surfaces, which coincides well with the experimental results.

Metal halide perovskite (MHP) structures that exhibit polarized photoluminescence (PL) have attracted significant interest in fabricating light field regulation elements for display, imaging, and information storage applications. We report a three-dimensional direct lithography of heterostructures for controllable polarized PL inside glass by laser-induced localized temperature engineering. The heterostructures consisted of oriented periodic structures (OPSs) and MHP nanocrystals, and the mechanism for hierarchical distribution of heterostructures was illustrated. The patterning of heterostructures for manipulable polarized PL can be used for information encryption, wave-plate, and polarized micro-LEDs.

The realization of next-generation transition-metal dichalcogenide based nanoscale devices demands stringent control over coherent in-plane heterostructures of atomically thin monolayers with exceptional properties. In this paper, we report atmospheric-pressure chemical vapor deposition growth of large-domain, coherent polymorphic in-plane heterostructures of monolayer WS2 on a SiO2/Si substrate with intriguing optical and electronic properties. The formation of in-plane heterostructures with 1H and 1T polymorphs was extensively analyzed using a variety of spectroscopic as well as microscopic techniques, along with lifetime luminescence imaging. High-angle annular dark-field scanning transmission electron microscopy revealed coexistence of the heterophases in monolayer WS2 heterostructures. Back-gated photoconductivity measurements in nanoscale field-effect-transistor device geometry and the rational design of a WS2 heterostructure pattern demonstrate optoelectronic applications. [ABSTRACT FROM AUTHOR]

Highly effective utilization of solar light is very important for water treatment via photocatalysis. To achieve this goal, we designed and synthesized an efficient full-spectrum-response photocatalyst based on MoSe2/TiO2 nanofibers. Ultrathin MoSe2 nanosheets with controllable size and density were evenly grown on electrospun TiO2 nanofibers by a simple solvothermal method. Under full spectrum irradiation, the photocatalytic reaction rates of MoSe2/TiO2 nanofibers for the removal of rhodamine B, tetracycline hydrochloride and K2Cr2O7 aqueous solutions were 7.7, 9.0, and 7.6 times higher than pure MoSe2, and were 2.4, 1.4, and 38 times higher than pure TiO2, respectively. The loading amounts of MoSe2 nanosheets have strong effects on their performance. All ultraviolet, visible, and near-infrared light collected by the heterostructures can be well converted to strong oxidizing •O2– and •OH and reducing electrons, which are useful active species for removing water pollutants of organics or reducible metal ions. The uniform interface contact and hierarchical heterostructure improved their charge separation and transfer properties, whereas their ultralong one-dimensional and nanofibrous network structure ensured their excellent reusable property. This work presents a new vision in designing full-spectrum-response photocatalysts with efficient and reusable properties. [ABSTRACT FROM AUTHOR]

High-entropy oxides (HEOs) have gained significant interest in recent years due to their unique structural characteristics and potential to tailor functional properties. However, the electronic structure of the HEOs currently remains vastly unknown. In this work, combining magnetometry measurements, scanning transmission electron microscopy, and element-specific X-ray absorption spectroscopy, the electronic structure and magnetic properties of the perovskite-HEO La(Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 epitaxial thin films are systemically studied. It is found that enhanced magnetic frustration emerges from competing exchange interactions of the five transition-metal cations with energetically favorable half-filled/full-filled electron configurations, resulting in an unprecedented large vertical exchange bias effect in the single-crystalline films. Furthermore, our findings demonstrate that the La(Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 layer with a thickness down to 1 nm can be used as a pinning layer and strongly coupled with a ferromagnetic La 0.7 Sr 0.3 MnO 3 layer, leading to a notable exchange bias and coercivity enhancement in a cooling field as small as 5 Oe. Our studies not only provide invaluable insight into the electronic structure of HEOs but also pave the way for a new era of large bias materials for spintronics devices.

Two-dimensional (2D) van der Waals heterostructures based on various 2D transition metal dichalcogenides are widely used in photodetection applications. However, their response time and photoresponsivity are limited, posing a challenge for their applications in high-sensitivity photodetection. Surface charge transfer doping (SCTD) has emerged as a novel doping approach for low-dimensional materials with high specific surface area and attracted considerable attention, as it is simple and effective, does not damage the lattice, and considers various types of dopants. Herein, we prepare p-i-n junction-based photodetectors via the SCTD of WSe 2 /ReS 2 heterojunctions using p-type dopant F 4 -TCNQ molecules, where doped WSe 2 serves as a p-type semiconductor, undoped WSe 2 acts as an intrinsic layer, and ReS 2 functions as an n-type semiconductor. The surface-charge-transfer-doped WSe 2 /ReS 2 heterojunction leads to a reduction in the Schottky barrier and an increase in the built-in electric field compared with the as-fabricated heterojunction. In the photovoltaic mode and under 785 nm laser illumination, the photodiode exhibits an increase in responsivity from 0.08 to 0.29 A/W, specific detectivity from 1.89 × 10 12 to 8.02 × 10 12 Jones, and the external quantum efficiency from 12.67 to 46.29%. Additionally, the p-i-n structure expands the depletion region width, resulting in a photovoltaic response time of 7.56/6.48 μs and a -3 dB cutoff frequency of over 85 kHz, an order of magnitude faster than the pristine response time. Herein, we derive an effective and simple scheme for designing high-performance, low-power optoelectronic devices based on 2D van der Waals heterostructures.

Developing a respiratory analysis disease diagnosis platform for the H 2 S biomarker has great significance for the real-time detection of various diseases. However, achieving highly sensitive and rapid detection of H 2 S gas at the parts per billion level at low temperatures is one of the most critical challenges for developing portable exhaled gas sensors. Herein, Cu 2 O-multiwalled carbon nanotube (MWCNT) heterostructures with excellent gas sensitivity to H 2 S at room temperature and a lower temperature were successfully synthesized by a facile two-dimensional (2D) electrodeposition in situ assembly method. The combination of Cu 2 O and MWCNTs via the principle of optimal conductance growth not only reduced the initial resistance of the material but also provided an ideal interfacial barrier structure. Compared to the response of the pure Cu 2 O sensor, that of the Cu 2 O-MWCNT sensor to 1 ppm of H 2 S increased nearly 800 times at room temperature, and the response time decreased by more than 500 s. In addition to the excellent sensitivity with detection limits as low as 1 ppb, the Cu 2 O-MWCNT sensor was extremely selective with low-temperature adaptability. The sensor had a response value of 80.6 to 0.1 ppm of H 2 S at -10 °C, which is difficult to achieve with sensors based on oxygen adsorption/desorption mechanisms. The sensor was used for the detection of real oral exhaled breath, confirming its feasibility as a real-time disease monitoring sensor. The Cu 2 O-MWCNT heterostructures maximized the advantages of the individual components and laid the experimental foundation for future applications of highly sensitive portable breath analysis platforms for monitoring H 2 S.

In this report, we investigate the room-temperature gas sensing performance of heterostructure transition metal dichalcogenide (MoSe 2 /MoS 2 , WS 2 /MoS 2 , and WSe 2 /MoS 2 ) thin films grown over a silicon substrate using a pulse laser deposition technique. The sensing response of the aforementioned sensors to a low concentration range of NO 2 , NH 3 , H 2 , CO, and H 2 S gases in air has been assessed at room temperature. The obtained results reveal that the heterojunctions of metal dichalcogenide show a drastic change in gas sensing performance compared to the monolayer thin films at room temperature. Nevertheless, the WSe 2 /MoS 2 -based sensor was found to have an excellent selectivity toward NO 2 gas with a particularly high sensitivity of 10 ppb. The sensing behavior is explained on the basis of a change in electrical resistance as well as carrier localization prospects. Favorably, by developing a heterojunction of diselenide and disulfide nanomaterials, one may find a simple way of improving the sensing capabilities of gas sensors at room temperature.

Synthetic materials and heterostructures obtained by the controlled stacking of exfoliated monolayers are emerging as attractive functional materials owing to their highly tunable properties. We present a detailed scanning tunneling microscopy and spectroscopy study of single layer MoS 2 -on-gold heterostructures as a function of the twist angle. We find that their electronic properties are determined by the hybridization of the constituent layers and are modulated at the moiré period. The hybridization depends on the layer alignment, and the modulation amplitude vanishes with increasing twist angle. We explain our observations in terms of a hybridization between the nearest sulfur and gold atoms, which becomes spatially more homogeneous and weaker as the moiré periodicity decreases with increasing twist angle, unveiling the possibility of tunable hybridization of electronic states via twist angle engineering.

Currently, severe shuttle effects and sluggish conversion kinetics are the main obstacles to the advancement of lithium-sulfur (Li-S) batteries. Modification of the battery separator by a catalyst is a promising approach to tackle these problems, but simultaneously obtaining rich catalytic active sites, high conductivity, and remarkable stability remains a great challenge. Herein, a flower-like MXene/MoS 2 /SnS@C heterostructure as the functional intercalation of Li-S batteries was prepared for accelerating the synergistic adsorption-electrocatalysis of sulfur conversion. The MXene skeleton constructs a three-dimensional conductive network that anchors polysulfides and enhances charge transfer. Meanwhile, the MoS 2 /SnS has rich active sites for accelerating polysulfide conversion, leading to excellent electrochemical performances. A battery with MXene/MoS 2 /SnS@C displays an extraordinary capacity of 836.1 mAh g -1 over 200 cycles at 0.5C and demonstrates a remarkable cycling stability with a capacity attenuation of approximately 0.051% per cycle during 1000 cycles at 2C. When the sulfur loading reaches 5.1 mg cm -2 , the capacity still maintains 722.4 mAh g -1 over 50 cycles. This research proposes a novel strategy to design stable catalysts for Li-S batteries with an extended lifespan.

Heterogeneous composite ZnS/SnS 2 is designed to meet various requirements for alkali metal-ion batteries. The composite is prepared using an electrostatic spinning method and encapsulated in N-doped carbon fibers after high-temperature vulcanization. The special structure of the composite provides a dependable interconnection and fast conductive network for alkali metal ions. The conductive carbon network shortens the diffusion path and greatly improves the migration efficiency of the alkali metal ions in the electrode. As expected, when the current density is 0.1 A g -1 , the ZnS/SnS 2 @NCNFs maintain a high discharge capacity of more than 1437.5, 1321.2, and 861.6 mA h g -1 for lithium-ion, sodium-ion, and potassium-ion batteries, respectively. What is more, a full cell using a prelithiated composite anode and a LiFePO 4 cathode is tested and shows excellent electrochemical performance. This work provides new perspectives for the development of novel anodes that can efficiently store alkali metal ions, as well as for the fine-structure design of materials.

The concept of integrating diverse functional 2D materials into a heterostructure provides platforms for exploring physics that cannot be accessed in a single 2D material. Here, physically mixing two 2D materials, MXene and MoS 2 , followed by freeze-drying is utilized to successfully fabricate a 3D MoS 2 /MXene van der Waals heterostructure aerogel. The low-temperature synthetic approach effectively suppresses significant oxidation of the Ti 3 C 2 T x MXene and results in a hierarchical and freestanding 3D heterostructure composed of high-quality MoS 2 and MXene nanosheets. Functionalization of MXene with a MoS 2 catalytic layer substantially improves sensitivity and long-term stability toward detection of NO 2 gas, and computational studies are coupled with experimental results to elucidate that the mechanism behind enhancements in the gas-sensing properties is effective inhibition of HNO 2 formation on the MXene surface, due to the presence of MoS 2 . Overall, this study has a great potential for expansion of applicability to other classes of two-dimensional materials as a general synthesis method, to be applied in future fields of catalysis and electronics.

Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) can be easily synthesized on SiO2/Si substrates by chemical vapor deposition (CVD). However, for practical applications, those 2D crystals usually need to be retrieved and placed onto target substrates. Hence, a robust and effective transfer process is required. Currently, the most widely used approach for transferring CVD- grown TMDs involves the spin-coating of a poly-(methyl methacrylate) (PMMA) support layer, followed by the wet etching of the SiO2 layer in hot NaOH. This transfer process often causes substantial accumulation of polymer residues as well as severe structural damage of TMDs induced during the etching of substrates at elevated temperatures. In this work, we present an alternative approach for the transfer of CVD-grown TMDs that can address the issues mentioned above. In this process, we replaced PMMA with cellulose acetate (CA) as a support layer and used buffered oxide etch (BOE) as an effective room-temperature etchant for SiO2. The CA-transferred TMDs exhibit well-preserved structural integrity and unaltered optical properties as well as largely improved microscale and nanoscale cleanliness with reduced wrinkles and cracks. Furthermore, we integrated our CA-transfer method with a deterministic positioning system that allowed microprecision transfer of the TMD layers. For example, a WS2-MoS2 vertical heterojunction with an electronically coupled and uniform interface was successfully created. The CA-transfer technique developed in this work represents a cleaner alternative to the PMMA-transfer method, thus permitting atomic resolution characterizations and the implementation of novel applications of CVD-grown TMDs and their heterostructures. [ABSTRACT FROM AUTHOR]

Over the last decades, there has been considerable interest in the synthesis of one-dimensional (1D) metal oxide nanostructures that can be used in gas sensor devices. Heterostructures, obtained by a combination of different semiconductor nanomaterials with different band energies, have been extensively studied in order to enhance their gas-sensing performance. In this context, our present study focuses on the investigation of chemiresistive- sensing capabilities of a combination of TiO2 nanoparticles and V2O5 nanowires obtained via hydrothermal treatment of the peroxo- metal complex. The formation of V2O5/TiO2 heterostructures was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. This study also proposes an efficient approach to produce 1D V2O5/TiO2 heterostructures with a good range of detection (0.09-1.25 ppm) and remarkable ozone-sensing properties related to repeatability and selectivity. [ABSTRACT FROM AUTHOR]

Semiconductor nanowires have attracted extensive interest as one of the best-defined classes of nanoscale building blocks for the bottom-up assembly of functional electronic and optoelectronic devices over the past two decades. The article provides a comprehensive review of the continuing efforts in exploring semiconductor nanowires for the assembly of functional nanoscale electronics and macroelectronics. Specifically, we start with a brief overview of the synthetic control of various semiconductor nanowires and nanowire heterostructures with precisely controlled physical dimension, chemical composition, heterostructure interface, and electronic properties to define the material foundation for nanowire electronics. We then summarize a series of assembly strategies developed for creating well-ordered nanowire arrays with controlled spatial position, orientation, and density, which are essential for constructing increasingly complex electronic devices and circuits from synthetic semiconductor nanowires. Next, we review the fundamental electronic properties and various single nanowire transistor concepts. Combining the designable electronic properties and controllable assembly approaches, we then discuss a series of nanoscale devices and integrated circuits assembled from nanowire building blocks, as well as a unique design of solution-processable nanowire thin-film transistors for high-performance large-area flexible electronics. Last, we conclude with a brief perspective on the standing challenges and future opportunities. [ABSTRACT FROM AUTHOR]

The field of thermoelectric research has undergone a renaissance and boom in the past two and a half decades, largely fueled by the prospect of engineering electronic and phononic properties in nanostructures, among which semiconductor nanowires (NWs) have served both as an important platform to investigate fundamental thermoelectric transport phenomena and as a promising route for high thermoelectric performance for diverse applications. In this Review, we provide a comprehensive look at various aspects of thermoelectrics of NWs. We start with a brief introduction of basic thermoelectric phenomena, followed by synthetic methods for thermoelectric NWs and a summary of their thermoelectric figures of merit (ZT). We then focus our discussion on charge and heat transport, which dictate thermoelectric power factor and thermal conductivity, respectively. For charge transport, we cover the basic principles governing the power factor and then review several strategies using NWs to enhance it, including earlier theoretical and experimental work on quantum confinement effects and semimetal-to-semiconductor transition, surface engineering and complex heterostructures to enhance the carrier mobility and power factor, and the recent emergence of topological insulator NWs. For phonon transport, we broadly categorize the work on thermal conductivity of NWs into five different effects: classic size effect, acoustic softening, surface roughness, complex NW morphology, and dimensional crossover. Finally, we discuss the integration of NWs for device applications for thermoelectric power generation and cooling. We conclude our review with some outlooks for future research. [ABSTRACT FROM AUTHOR]