查看更多>>摘要：? 2022 Elsevier B.V.The development of the heterostructures of one-dimensional (1D) and two-dimensional (2D) semiconductors is a prospective strategy to design an efficient photoanode for photoelectrochemical (PEC) water splitting. In this study, we report the controllable growth and beneficial heterojunction effects of vertically-aligned 2D MoS2 nanosheets (NSs) on 1D WO3 nanorods (NRs) for efficient PEC water-splitting reactivity. MoS2 NSs were decorated on WO3 NRs by metal–organic chemical vapor deposition. In comparison with pristine WO3 NRs, vertical MoS2 NSs-decorated WO3 NRs possessed an enlarged surface area, improved light absorption performance, and appropriately organized the staggered heterojunction of MoS2/WO3 for promoting the PEC reaction. PEC performance was considerably affected by the size of vertical MoS2 NSs. MoS2/WO3 structure with appropriate MoS2 NS size showed a 72% enhancement in PEC performance compared with pristine WO3. These results provide a valuable strategy for constructing staggered heterojunctions and introducing morphology control for beneficial PEC applications.
查看更多>>摘要：? 2022 Elsevier B.V.The exploration of suitable anode materials to overcome key issues of electrode volume fluctuation and sluggish electronic/ionic transport dynamics caused by the large radius of sodium/potassium ions is an urgent need for energy storage. Herein, a heterogenetic nickel-iron selenide containing vacancies and schottky junctions within N-graphene porous matrix to realize external and internal charge transport is constructed via a one-pot in-situ carbonization and selenization route. In the composite, the iron selenide possessing metallic property acts as the conductor incorporated with nickel selenide semiconductor for constructing schottky junctions and vacancies to induce internal charge transfer and transport of the active material, and the N-graphene not only enhance the interparticle conductivity by bridging the selenides, but also relieve the volume fluctuation and keep integrity without agglomeration of nanocrystals. Profiting from the synergistic effect, the material exhibits boosted electrochemical properties for sodium (264 mA h g?1 after 1000 cycles at 1.0 A g?1) and potassium (115 mA h g?1 after 500 cycles at 0.5 A g?1) storage. And the thorough understanding of electrochemical mechanism on the raised performance is explicitly interpreted by combining ex-situ characterization results and density functional theoretical calculations.
查看更多>>摘要：? 2022 Elsevier B.V.High thermal stability and quantum efficiency are the two very significant factors for phosphors when concerning all kinds of related applications. Therefore, it is still main research topics as long as referencing to the luminescence phosphors. It is well known that deep trap and large band gap are beneficial to excellent thermal stability. In this work, a series of Na2BaCa1-xSrx(PO4)2:0.03Eu2+ phosphors have been prepared by traditional solid state reaction. When the Sr2+ content increases, the emission intensity exhibits a blue shift phenomenon with the highest peak around 448 nm caused by the varied centroid shift (εc) and the crystal field splitting (εcfs). The thermal stability of Na2BaCa0.2Sr0.8(PO4)2:0.03Eu2+ phosphor still approaches to 100.3% of that room temperature at 150 °C, while the external and internal quantum efficiency are greatly enhanced from 19.92% to 62.53%. It is due to the effect of the cation disorder by introducing the high level of Sr ion, which create the deep trap and broaden the bandgap, resulting in the anti-thermal quenching behavior and enhanced quantum efficiency. Moreover, Rietveld refinements, microstructure, decay curves and thermoluminescence are also adopted to shed light on related mechanism of luminous performance. Furthermore, a pc-WLED device has been fabricated through Na2BaCa0.2Sr0.8(PO4)2:0.03Eu2+ blue phosphor mixed with commercial yellow phosphor (SrSi2O2N2:Eu2+) and red phosphor (Sr2Si5N8:Eu2+), which performs a color temperature of 4721 K with a high color rendering index of Ra = 91.9. In view of zero thermal quenching and favorable quantum efficiency, this new phosphor is a prospect candidate for blue phosphors in WLED application. Further, the work provides a new method and reference for the great enhancement of thermal stability and quantum efficiency of luminescence materials.
查看更多>>摘要：? 2022 Elsevier B.V.The development of high-efficiency and cheap electrocatalysts for hydrogen evolution reactions (HER) is of great importance for the electrochemical production of hydrogen. In this study, self-supported CoMoS on carbon nanofiber (CoMoS@CNF) catalysts were prepared through a one-step hydrothermal method using carbonized, electrospun polyacrylonitrile–dopamine (DA) polymeric fibers. The –OH group on DA was utilized to immobilize 1,2,3,4-Butanetetracarboxylic acid on the surface of the modified fiber, which consequently captured Co and Mo ions. Self-supported CoMoS nanosheet and nanosphere clusters grew on the surface of the CNF. The core–shell and layered nanosheet stacked structures created abundant accessible active sites, convenient ion diffusion pathways, and opened channels for the rapid release of the evolved H2. Density functional theory calculations showed that the heterojunctions constructed from CoS2 and Mo2S3 had low free energies for the adsorption of hydrogen. The prepared CoMoS@CNF electrode required a low overpotential (105.2 mV) to reach 10 mV cm?2 in 1 M KOH and showed no deterioration in the electrochemical performance even after 20 h of continuous operation at a 10 mV overpotential. The excellent activity and stability of the self-supported CoMoS@CNF electrocatalysts toward HER in alkaline medium is possibly due to its advantageous electronic and geometrical structure.
查看更多>>摘要：? 2022 Elsevier B.V.0.79ZnAl2O4-0.21TiO2 microwave dielectric ceramics are ideal materials for preparing 5 G lens antennas. However, conventional processing methods are difficult to meet the requirements of microwave devices for high precision and designed complicated structures. Additive manufacturing technologies provide opportunities for the fabrication of these devices. Herein, we fabricated 0.79ZnAl2O4-0.21TiO2 ceramics by digital light processing (DLP). The slurry with 2 wt% dispersant content showed favorable dispersion effect and stability. The optimal penetration depth of 44.64 μm and critical energy dose of 3.04 mJ/cm2 were obtained. After sintering, the 0.79ZnAl2O4-0.21TiO2 ceramic only kept ZnAl2O4 phase and TiO2 phase. The relative density could reach 95.29%, which is comparable to that of dry-pressed sample. With the increase of sintering temperature, dielectric constant (εr) and quality factor (Q×f) of 0.79ZnAl2O4-0.21TiO2 ceramic increased first and then decreased. The sintered ceramic at 1550 °C exhibited excellent microwave dielectric properties (εr = 11.55, Q×f = 62,266 GHz, τf = ?0.64 ppm/°C). The results indicate that DLP is a promising technology to fabricate high-performance microwave dielectric ceramics with complex structures.
查看更多>>摘要：? 2022 Elsevier B.V.Inspired by biological mechanoreceptors, we present a flexible artificial mechanoreceptor (FAM) based on high-performance VO2 insulator-metal transition (IMT) memristor with the functions of sensing, spikes coding and information fusion for the anthropomorphic neurorobotics. The flexible VO2 IMT memristors with the structure of Ti/Pt/VO2/Pt via-hole show bi-directional threshold switching performance, good endurance (>2 ×109) and excellent flexibility (>103 bending cycles). The FAM comprised of three receptors (flexible pressure sensors) and one flexible VO2 IMT memristor is able to detect, code and fuse the pressure information from different receptors into spike trains similar to the biological SA-Ⅰ mechanoreceptors, laying the foundation for the flexible electronic skin of anthropomorphic neurorobotics in the future.
查看更多>>摘要：? 2022 Elsevier B.V.Materials with structural hierarchy have drawn great attenuation due to their fascinating physical and mechanical properties given by the unique microstructures. In this study, hierarchical SiC fiber aerogel was successfully developed via a simple method by using carbonized silk fiber mat as a template and subsequent in-situ growth of SiC nanowires array through carbothermal reduction at high temperature. The formation mechanisms of hierarchical SiC fiber aerogel based on a vapor-solid-liquid process were discussed. Owing to the highly porous structure supported by SiC nanowires, the aerogel could show an ultralight density of 0.04 g/cm3 and a compression fatigue resistance of 10 cycles at 40% strain with small and stable energy loss coefficients. The electromagnetic (EM) investigation suggests that the aerogel could serve as a wideband microwave attenuator with a minimal reflection loss (RL) of ? 68 dB and a maximum effective attenuation bandwidth (EAB, RL<?10 dB) of 7.2 GHz when embedded in silicone matrix at 10 wt% loading ratio. Additionally, the hierarchical SiC fiber aerogel reveals remarkably low thermal conductivity of 0.027 W/m·K, suggesting enormous potential for thermal insulation.
查看更多>>摘要：? 2022 Elsevier B.V.Focusing on the special electrical conductivity and corrosion resistance of Ti4O7, this work proposes for the first time to reduce TiO2 film grown in situ on Ti substrate in a high-temperature tube furnace by using Ti/TiO2 mixed powder as reducing agent to obtain Ti4O7 surface coating. By characterization, the surface of the coated sample is identified as a Ti4O7 coating, with a partially unconverted TiO2 present at the interface between the Ti substrate and the Ti4O7 surface coating. The electrochemical, water contact angle and surface contact resistance tests show that the Ti4O7 surface coating provides superior protection to the Ti bipolar plate in the simulated proton exchange membrane fuel cell cathode environment, and simultaneously improving the electrical conductivity and water contact angle of the sample.
查看更多>>摘要：? 2022 Elsevier B.V.Three-dimensional (3D) β-In2S3 offers photocatalytic advantages by virtue of its strong and broadband optical absorption resulting from its large effective surface area and a high density of sulfur vacancies. However, the use of surfactants and reducing agents complicates the synthesis process and causes undesirable agglomeration while forming the 3D structures, degrading the photocatalytic efficiency of 3D In2S3. Here we have prepared the surfactant-free In2S3 nanoflowers by the thermal assembly of two-dimensional (2D) In2S3 nanosheets and achieved a substantial enhancement of the optical absorption and the tunable bandgap narrowing. We show that owing to the intrinsic structure of our In2S3 nanoflowers that preserves the unit geometry of 2D In2S3 nanosheets, the rate of photocatalytic performance was enhanced by 200% just by the post-annealing process. The facile method used to prepare In2S3 nanoflowers expedites the practical application of 3D In2S3 for energy and environmental purposes.
查看更多>>摘要：? 2022The contradictory between thermal stability and operation speed has traditionally been the restriction to apply phase change memory (PCM) in the harsh condition. For providing a feasible solution, in this paper, Ru-modification is introduced to boost the data retention of Sb2Te3 without sacrificing the operation speed over the conventional Ge2Sb2Te5 compound. The both experimental and simulation results indicate that Ru locates at the grain boundary to inhibit the formation of large grains. Several performance of the device was enhanced, including: ultra-high 10-year data retention above 200 °C, lower Reset voltage about 1.9 V at 100 ns pulse width and a fast operation speed of 6 ns. Refined grains and smaller density change contributed to the reduced voltage and increased endurance. These findings demonstrated that PCM based Ru doped Sb2Te3 will be a potential application in high performance memories.
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