Tailor-made porous nanotube arrays are of great technological interest for the development of high-performance optical and electrochemical energy storage devices. Herein, we report facile successive ...electro-deposition (ED) methods to fabricate three-dimensional (3D) hierarchical porous NiO nanotube arrays on nickel foam with the help of ZnO nanorod template. The obtained hierarchical porous NiO nanotubes have a diameter of ∼170 nm and consist of interconnected branch nanoflakes of ∼10 nm. The resulting NiO nanotube arrays are well characterized as positive electrode materials for supercapacitor application by cyclic voltammetry (CV) and galvanostatic charge/discharge measurements. Due to the unique architecture, the NiO nanotube arrays exhibit a high capacitance of 675 F g−1 at the 2 A g−1 and 569 F g−1 at 40 A g−1, respectively, as well as good cycling stability. The proposed synthesis method is expected for fabrication of other nanotube arrays for applications in solar cells, gas sensors and Li ion batteries.
Hierarchical porous NiO nanotube arrays are prepared via facile successive electro-deposition methods and show superior supercapacitor performance with high capacitance. Display omitted
•Construct a hierarchical porous NiO nanotube array.•Porous nanotube array shows high pseudo-capacitive properties.•Porous nanotube array structure is favorable for fast ion and electron transfer.
SrFeO x (SFO x ) compounds exhibit ionic conduction and oxygen-related phase transformation, having potential applications in solid oxide fuel cells, smart windows, and memristive devices. The phase ...transformation in SFO x typically requires a thermal annealing process under various pressure conditions, hindering their practical applications. Here, we have achieved a reversible phase transition from brownmillerite (BM) to perovskite (PV) in SrFeO2.5 (SFO2.5) films through ionic liquid (IL) gating. The real-time phase transformation is imaged using in situ high-resolution transmission electron microscopy. The magnetic transition in SFO2.5 is identified by fabricating an assisted La0.7Sr0.3MnO3 (LSMO) bottom layer. The IL-gating-converted PV phase of a SrFeO3−δ (SFO3−δ) layer shows a ferromagnetic-like behavior but applies a huge pinning effect on LSMO magnetic moments, which consequently leads to a prominent exchange bias phenomenon, suggesting an uncompensated helical magnetic structure of SFO3−δ. On the other hand, the suppression of both magnetic and exchange coupling signals for a BM-phased SFO2.5 layer elucidates its fully compensated G-type antiferromagnetic nature. We also demonstrated that the phase transition by IL gating is an effective pathway to tune the resistive switching parameters, such as set, reset, and high/low-resistance ratio in SFO2.5-based resistive random-access memory devices.
Co(OH)2 nanocone arrays are prepared by a facile hydrothermal synthesis method. The Co(OH)2 nanocones are single crystalline in nature and have an average diameter of about 200 nm. The ...pseudocapacitive behavior of the Co(OH)2 nanocone arrays is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2 M KOH. As cathode for supercapacitor, the Co(OH)2 nanocone arrays exhibit a capacitance of 562 F g−1 at 2 A g−1 as well as rather good cycling stability. The enhanced supercapacitor performances are due to the porous array architecture providing fast ion and electron transfer, large reaction surface area and good strain accommodation.
► β-Co(OH)2 nanocone arrays are prepared by a hydrothermal synthesis method. ► β-Co(OH)2 nanocone arrays with high capacitance for supercapacitors application. ► 1D nanocone arrays structure keeps structure stable with good strain accommodation.
Microstructural aspects have fundamental influences on the fatigue crack characteristics of materials. In this paper, effects of inclusions, grain boundaries (GBs) and grain orientations on the ...fatigue crack initiation and propagation behavior in a 2524-T3 aluminum alloy have been investigated using in-situ scanning electron microscope (SEM) fatigue testing and electron back scattering diffraction (EBSD). The results show that, potential fatigue cracks tend to nucleate along coarse and closely spaced inclusion particles or high-angle GBs. Coarse inclusion particles drastically accelerate local crack growth rates. A model of series crack growing stages is given based on the observation of initiation and growth of cracks at the inclusion region. GBs serve to impede the crack tip from propagation and cause large angle crack deflections, which greatly affects local crack propagation behaviors. In addition, fatigue crack shows a strong tendency to propagate transgranularly grains with high Schmid factors (SFs) and avoid grains with low SFs.
The evolution of morphologies, orientation relationships (ORs), and twinning behaviours of the T-phase in Al-Cu-Mg-Mn alloys were investigated, during homogenisation at 485 °C for times ranging from ...0.5 to 1000 h, by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Results shows that the T-phase takes on a rod-like shape elongated uniformly parallel to the 〈010〉Al direction. Four different shape categories of cross-sections of the T-phase (T-CSs) and three different types of ORs between the T-phase and Al matrix were identified. The T-CS has a clear relationship with the ORs of the T-phase. When the T-CS is a parallelogram (P) shape, the OR of the T-phase is OR-II, and an irregular-polygon (IP) shape, the ORs of the T-phase contain both OR-I and OR-II, while a shell (S) or decagon (D) shaped T-phases have all three ORs. During homogenisation, the P-shaped CS is gradually transformed to the IP-shape, followed by transformation to the S- or D-shapes. Anti-phase boundaries (APBs) along {101}T planes exist extensively in the T-phase, especially for that with a P-shaped CS. With the increase of homogenisation time, the number of APBs in the T-phase decreases and that of its T-twins increases.
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•Four different shape categories of cross-sections of T-phase were identified.•There are three orientation relationships between the T-phase and Al matrix.•The T-cross-section shape relates to its orientation relationship with the matrix.•Homogenisation decreases anti-phase boundaries in the T-phase and increases T-twins.
Printed flexible electronics have emerged as versatile functional components of wearable intelligent devices that bridge the digital information networks with biointerfaces. Recent endeavors in plant ...wearable sensors provide real‐time and in situ insights to study phenotyping traits of crops, whereas monitoring of ethylene, the fundamental phytohormone, remains challenging due to the lack of flexible and scalable manufacturing of plant wearable ethylene sensors. Here the all‐MXene‐printed flexible radio frequency (RF) resonators are presented as plant wearable sensors for wireless ethylene detection. The facile formation of additive‐free MXene ink enables rapid, scalable manufacturing of printed electronics, demonstrating decent printing resolution (2.5% variation), ≈30000 S m−1 conductivity and mechanical robustness. Incorporation of MXene‐reduced palladium nanoparticles (MXene@PdNPs) facilitates 1.16% ethylene response at 1 ppm with 0.084 ppm limit of detection. The wireless sensor tags are attached on plant organ surfaces for in situ and continuously profiling of plant ethylene emission to inform the key transition of plant biochemistry, potentially extending the application of printed MXene electronics to enable real‐time plant hormone monitoring for precision agriculture and food industrial management.
The all‐MXene‐printed radio frequency (RF) resonators are developed to detect plant ethylene emission in situ and wirelessly. Basing on screen printable additive‐free MXene ink, flexible MXene electronics and uniform palladium nanoparticles are fabricated for selective and sensitive ethylene detection, shedding light on scalable manufacturing of plant wearable devices for precision agriculture and food industry.
Porous Co(OH)2/Ni composite nanoflake array is prepared by combing hydrothermal synthesis and electrodeposition methods. The as-prepared Co(OH)2/Ni composite nanoflake array exhibits a highly porous ...array structure composed of free-standing nanoflakes with thicknesses of 35–40nm. The pseudocapacitive behavior of the Co(OH)2/Ni composite nanoflake array is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2M KOH. As cathode material for supercapacitor, the porous Co(OH)2/Ni composite nanoflake array exhibits weaker polarization, higher electrochemical activity and better cycling performance as compared to the unmodified Co(OH)2 nanoflake array. The Co(OH)2/Ni composite nanoflake array shows specific capacitances of 1310Fg−1 at 1Ag−1 and 1148Fg−1 at 40Ag−1, much higher than those of the unmodified Co(OH)2 nanoflake array (1017Fg−1 at 1Ag−1 and 775Fg−1 at 40Ag−1). The enhancement of supercapacitor properties is due to the introduction Ni in the composite array, which improves the electric conductivity of the film electrode with fast reaction kinetics.
Abstract
Four ultraluminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the
z
∼ 2 ULIRG population. The ...objects were originally selected at 24
μ
m and have strong polycyclic aromatic hydrocarbon emission features observed with Spitzer/Infrared Spectrometer. The four objects have similar stellar masses of ∼10
11
M
⊙
but otherwise are quite diverse. One is an isolated disk galaxy, but it has an active nucleus as shown by X-ray observations and by a bright point-source nucleus. Two others are merging pairs with mass ratios of 6–7:1. One has active nuclei in both components, while the other has only one active nucleus: the one in the less-massive neighbor, not the ULIRG. The fourth object is clumpy and irregular and is probably a merger, but there is no sign of an active nucleus. The intrinsic spectral energy distributions for the four active galactic nuclei in these systems are typical of type-2 QSOs. This study is consistent with the idea that even if internal processes can produce large luminosities at
z
∼ 2, galaxy merging may still be necessary for the most luminous objects. The diversity of these four initial examples suggests that large samples will be needed to understand the
z
∼ 2 ULIRG population.
By controlling local substrate temperature in a chemical vapor deposition system, we have successfully achieved spatial composition grading covering the complete composition range of ternary alloy ...CdSSe nanowires on a single substrate of 1.2 cm in length. Spatial photoluminescence scan along the substrate length shows peak wavelength changes continuously from ∼500 to ∼700 nm. Furthermore, we show that under strong optical pumping, every spot along the substrate length displays lasing behavior. Thus our nanowire chip provides a spatially continuously tunable laser with a superbroad wavelength tuning range, unmatched by any other available semiconductor-based technology.
Delafossite-structured CuAlO2 materials with and without vacancy defects were investigated comparatively using the first principle calculation method. The method based on the density functional ...theory, has been carried out to search the systems’ ground states and supplies the corresponding electronic properties. In the process of calculations, ultrasoft pseudo-potentials and PBE-GGA functionals are chosen for the atoms and exchange-correlation interactons between electrons, respectively. The geometry optimization shows the Al vacancy causes a larger lattice deformation than the vacancies of Cu and O atoms. The results of Mulliken charge also verify this conclusion. The calculations of vacancy formation energy and elastic constants indicate the Cu vacancy has the lowest formation energy, the highest Pugh ratio and the smallest Zener anisotropy factor, which means the introduction of Cu vacancy can improve the functional applications of Cu-based delafossites, e.g. p-type conductivity, ductility, etc.
