查看更多>>摘要：? 2022 Elsevier B.V.The increasing demand for flexible electronics encourages the innovative and functional designs of electrode materials with high performance and compressibility. In this work, we report a compressible supercapacitor electrode which is prepared by coating electrically active NiO/MnO2/carbon nanotube (CNT) composite onto a sponge. A cube of sugar was used as the template to obtain the sponge through infiltration and cross-linking of polydimethylsiloxane (PDMS). NiO/MnO2/CNT was deposited on the PDMS sponge to generate substantial amount of interface, resulting in a specific capacitance of 23 F/g at 0.1 A /g in a three-electrode system and 1.32 F/g at 0.5 mA in a symmetric supercapacitor. The proposed system exhibits excellent cycling stability with capacitance retention over 10.000 cycles. The strong adhesion of the binary metal oxides and carbon material onto the porous nonconductive sponge enables mechanical stability under compression-release cycles. Our study indicates that this electrode is a promising candidate for applications in flexible electronics. Furthermore, this research might guide the development of flexible, high-performance, and low-cost electrodes, which will be useful in wearable energy storage systems.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, we theoretically study the influence, at finite temperature, of the intermediate valence on the local moment formation and the magnetic hyperfine field at a Ce impurity diluted in RZn (R = Gd, Tb, Dy). The temperature dependence of the local magnetic moments and related hyperfine magnetic interaction is calculated by a functional integral approach in the static approximation, thereby extracting the 4f Ce valence at the range of temperature T ≤ TC (TC = critical temperature). Our self-consistent calculation shows that the intermediate valence model, focusing on the temperature dependence, explains the experimentally observed magnetic hyperfine fields at Ce impurity in these compounds, in particular exhibiting the two regimes of the magnetic hyperfine fields (and local magnetic moments) with temperature.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, the multilayer magnetic-carbon composites were precisely constructed by the Particle Swarm Optimization algorithm to achieve an ultra-broadband electromagnetic wave absorbing (EMA) performance. Composite with different content of magnetic Fe3S4 hollow microspheres and carbon nanotubes were prepared as absorbing fillers to obtain four basic monolayer EMA materials. Based on their different electromagnetic parameters, various multilayer structures were designed and further simulated via the finite element method. In a series of designed EMA materials with intense absorption and broad bandwidth, a 2-layer model with 3.8 mm thickness was selected as an optimal structure, owning to its excellent simulation EMA property with a minimum reflection loss of ?40 dB and an extended qualified bandwidth value of 11.7 GHz. According to the designed structural parameters, the 2-layer composite was successfully prepared and the measured results were in good agreement with the simulated properties, confirming the accuracy of the multilayer optimization. The FEM simulation analysis revealed that the high EMA performance of the multilayer composites is attributed to the enhancement of the electromagnetic loss capability as well as the improvement of broadband impedance matching between the material surface and air.
查看更多>>摘要：? 2022 Elsevier B.V.The ternary Bi2MoO6-Bi2O3-Ag3PO4 photocatalysts were fabricated via hydrothermal and precipitation methods. Various characterizations proved that the Bi2O3 nanodots and spherical Ag3PO4 particles were embedded on Bi2MoO6 nanoflakes to form the ternary heterojunction. Compared to single Bi2O3, Bi2MoO6 and the binary Bi2MoO6-Bi2O3, the ternary composites at optimum Ag3PO4 content possess a significantly high visible-light degradation rate of tetracycline which is 3.2, 4.3 and 1.9 fold that of Bi2MoO6, Bi2O3 and Bi2MoO6-Bi2O3, respectively. The enhanced photocatalytic performance is attributed to the formation of ternary heterojunction that could greatly promote the transfer and separation of photo-generated carriers and extend the visible-light response range. The superoxide radical (·O2?) played a key role in the photocatalytic process and the photocatalytic mechanism of the ternary n-n-p heterojunctions were proposed. This work could offer a new insight in manufacturing ternary photocatalysts for the degradation of tetracycline under visible light irradiation.
查看更多>>摘要：? 2022 Elsevier B.V.Manganese-based materials have been considered as promising electrode materials for aqueous zinc-ion batteries (ZIBs). However, the development of manganese-based materials is seriously restricted by their low electrical conductivity and sluggish reaction kinetics. In the present work, ultrathin birnessite-type δ-MnO2 nanosheets branched onto N-doped carbon nanotubes grown on carbon cloth substrate (CC/NCNTs/δ-MnO2) have been rational synthesized as a binder-free cathode electrode for aqueous ZIBs. The CC/NCNTs/δ-MnO2 cathode possesses the desired merits including high electrical conductivity, large specific surface area, abundant active sites, fast ion diffusion, good structural stability and free of any polymer binders. When evaluated as a binder-free cathode electrode for aqueous ZIBs, the CC/NCNTs/δ-MnO2 exhibits high areal capacity and energy density of 1.95 mAh cm?2 and 2.56 mWh cm?2 at a current density of 0.4 mA cm?2, respectively, as well as decent rate capability and cycling stability. This work could provide an effective method to construct high-performance binder-free cathode electrodes for aqueous ZIBs.
查看更多>>摘要：? 2022 Elsevier B.V.Mixed Ni-Mn ferrite spinel nanoparticles embedded in SiO2 matrix were prepared by sol-gel method, followed by annealing at 300 and 1000 °C. The thermal analysis and Fourier transform infrared spectroscopy confirmed the formation of Ni-, Mn- and Co- malonate precursors and their decomposition to ferrites. The X-ray diffraction data showed the presence of poorly crystallized Ni-Mn ferrite at 300 °C and of Ni-Mn ferrite accompanied by α-Fe2O3, cristobalite, quartz and Fe2SiO4. at 1000 °C. The transmission electron microscopy revealed spherical shape ferrite particles of 19–46 nm diameter, that increase with the increase of Ni content and annealing temperature. For the samples with low Ni content, the pores are larger, their size reaching 100 ?, while for the samples with high Ni content the pores are smaller, their size being lower than 50 ?. The specific surface area increases with the increase of Ni content up to 0.7/0.3 Ni/Mn ratio and after remains constant. The isotherms were used to calculate the rate constants for the decomposition of malonate precursors to ferrites and the activation energy for each ferrite. The samples show a broad response in both UV and visible range, with the maximum in visible domain. Ni0.5Mn0.5Fe2O4 sample shows the best sonophotocatalytic activity against Rhodamine B solution under visible light irradiation. The prepared Ni-Mn ferrites may have potential application for water and wastewater decontamination.
查看更多>>摘要：? 2022 Elsevier B.V.The martensitic transformation behaviors, magnetic properties, crystal structures, and entropy change (ΔS) of Ni50?xCoxMn50?ySny alloys were systematically investigated. Samples were prepared by induction melting, followed by solution heat treatment at 1273 K for 1 day and quenching. A magnetic phase diagram with a broad range of compositions was established, from which a series of alloys with varying Co concentrations was selected, such that their martensitic transformation starting temperatures (TMss) were near room temperature. The thermal and magnetic-field hystereses of these samples were systematically investigated, and a clear composition dependence was observed. The dissipation energy (Edis), which governs the transformation hysteresis, was found to be smaller for alloys with x = 5–8 than for those with x = 0–3. This behavior was found to originate from the difference in crystal structures of the martensite phases, i.e., the crystal structures of the martensite phases are 4O and 6M for x = 0–3 and x = 5–8, respectively. Moreover, the geometric compatibility between the parent and martensite phases was found to be the direct cause of the difference in dissipation energy in Ni–Co–Mn–Sn alloys.
查看更多>>摘要：? 2022 Elsevier B.V.Graphene-based microwave absorption materials have been profoundly and extensively investigated because of their excellent properties and is potential absorbing material. However, graphene-based absorbing materials about low-frequency remain to be researched and developed. Here we obtain that Reduced Graphene Oxide (RGO) modified with magnetic xNi/yNiO nanoparticles by a simple hydrothermal method, which presents a large reflection loss (RL) in S-band. The electromagnetic parameters, attenuation constants and impedance matching of xNi/yNiO/RGO composite were analyzed to determine the appropriate ratio of magnetic xNi/yNiO nanoparticles and GO. The maximum RL can reach ?46.5 dB with a thickness of 3.6 mm at 3.57 GHz with a loading wax ratio of 15 wt%. The probability of falling on EAB is maximized to cover 94.5% of the S-band. Notably, the RL and efficient absorption bandwidth (EAB) of xNi/yNiO/RGO composite material can be adjusted according to the quarter wavelength matching theory. All the results indicate that xNi/yNiO/RGO composite has a great potential of low frequency absorbing material for low frequency absorbing material research on practical.
查看更多>>摘要：? 2022 Elsevier B.V.Zinc oxide (ZnO) nanoparticles are superior photocatalysts for pollutant degradation due to their stability, low hazard, and high photosensitivity. The morphology of this material is one of the key factors influencing the performance of pollutant degradation. In fact, studies on the effects of different ZnO morphologies on thiophene desulfurization via photocatalysis process are limited. Thus, this study focuses on the performance of different ZnO morphologies for thiophene desulfurization. Nine ZnO nanoparticles were synthesized and categorized into two groups, namely flower-like and non-flower-like ZnO. Flower-like ZnO included flakes, clusters, rods, and needles, while the non-flower-like ZnO comprised nanoballs, short-nanorods, nanocubes, and nanoporous. The physical properties of all ZnO morphologies were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier-transform infrared (FTIR), and compared with commercial ZnO. From the findings, flower-like ZnO flakes showed the highest performance in thiophene desulfurization (30%). High pH and turbidity reduction in the permeate confirmed that the thiophene compound in the solution was highly degraded after treatment. Moreover, all ZnO morphologies applied to pseudo-second-order models due to higher linear regression (R2) values. Greater thiophene desulfurization was indicated by the highest Ce value of ZnO flakes (909.09 mg/g). The optimum conditions for thiophene desulfurization were at pH 7 and 0.05 g/L ZnO flakes loading for 90 min contact time.
查看更多>>摘要：? 2022 Elsevier B.V.For the first time, Fe3O4-based high-entropy spinel oxides are studied for the electrochemical production of hydrogen peroxide. Among those investigated substances, (Fe0.2Zn0.2Co0.2Ni0.2Cu0.2) Fe2O4 shows significantly enhanced 2e-ORR electrocatalytic property. The H2O2 selectivity is found to range from 69.48% to 85.78% under a wide potential window of 0.2 ~ 0.65 V with excellent durability up to 24 h. The improved performance is attributed to the high concentration of oxygen vacancies on the material surface and the multicomponent co-interaction in the high-entropy oxide. We believe this finding will broaden the application of high-entropy spinel oxide catalysts for viable electrochemical production of H2O2.
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