查看更多>>摘要：? 2022 Elsevier B.V.Porous carbon nanotubes with unique structure is an ideal electrode material for supercapacitors. However, the synthesis of porous carbon nanotubes requires expensive catalysts such as heavy metals or heavy metal salts, which limits their wider application. To solve the problem, a one-step high-temperature potassium chloride-catalyzed strategy is proposed to directly grow porous carbon nanotubes. Magnesium reacts with carbon dioxide to form carbon as the carbon source and magnesium oxide that can form porosity of carbon nanotubes. Low-cost and recyclable potassium chloride can replaced expensive heavy metals or heavy metal salts to catalyze the growth of porous carbon nanotubes. The obtained porous carbon nanotube (CC-KCl-700) show great advantages in structure and delivers excellent electrochemical properties and its specific capacitance reaches up to 334.4 F g?1. After 10,000 cycles at 10 A g?1, the capacitance of the CC-KCl-700 still reaches to 230 F g?1. Beside, the assembled symmetric supercapacitor with a high energy density and great rate performance can successfully provide energy for devices.
查看更多>>摘要：? 2022 Elsevier B.V.Mn4+-doped oxide phosphors with bright red emission show promising application potential in plant cultivation lighting. However, finding suitable oxide hosts for Mn4+ ions incorporation is still a challenge. Herein, an efficient deep-red-emitting SrKYTeO6:Mn4+ phosphor was achieved through the co-substitution of [K+?Y3+] for [Sr2+?Ca2+] in non-luminous Sr2CaTeO6:Mn4+ for the first time. Crystal structure analysis reveals that the new SrKYTeO6 compound is isostructural to Sr2CaTeO6, which belongs to the monoclinic P21/n (14) space group. Upon 338 nm excitation, the SrKYTeO6:Mn4+ phosphor exhibits a deep-red emission band peaking at 680 nm, resulting from the 2Eg → 4A2 g transition of Mn4+ ion. The concentration of Mn4+ ion in SrKYTeO6 is optimized to be 0.4 mol%, and color purity and internal quantum efficiency (IQE) of this phosphor reach as high as 98.5% and 44.3%, respectively. The phosphor also possesses good thermal stability with the emission intensity at 423 K maintaining 56% of the initial value at 298 K. These superior luminescent properties could be attributed to the change of local crystal environment induced by distorting the internal [TeO6] octahedra. This work not only acquires an efficient SrKYTeO6:Mn4+ phosphor for application in plant cultivation lighting but also offers a replicable strategy for further exploring novel Mn4+-doped perovskite phosphors.
查看更多>>摘要：? 2022The severe shuttle effect of polysulfides in lithium-sulfur (Li-S) batteries leads to rapid performance deterioration. Herein, a functional separator composed of TiO2@surface-modified carbon nanotubes composite on polypropylene (PP) separator (donated as TiO2@SCNT/PP) is developed toward the effective blocking of polysulfide shuttle. The as-assembled Li-S batteries using this functional separator with the strongly polar TiO2 and highly conductive CNTs demonstrated considerably enhanced reversible capacity, cycling performance and reaction kinetics. The corresponding simple sulfur cathode with 70 wt% elemental sulfur powders exhibits a high initial discharge capacity of 1103.9 mAh g?1, a high capacity of 848.0 mAh g?1 after 200 cycles at 0.5 C, and a capacity decay of only 0.066% per cycle over 900 cycles. Moreover, a high reversible capacity of 746.5 mAh g?1 is maintained after 300 cycles at 1 C. In contrast, the low reversible capacity of 218.5 mAh g?1 at 0.5 C is obtained without the use of the TiO2@SCNT/PP.
查看更多>>摘要：? 2022 Elsevier B.V.The g-C3N4/rGO/ZnO-Ag (GCRZA) composite photocatalyst (PC) prepared by the facile hydrothermal method was effectively studied. The structural, morphological and optical, properties of as-synthesized materials were characterized by various characterization techniques. Photocatalytic activity of the as-prepared composite was examined using rhodamine B and methylene blue mixed (RhB+MB) aqueous dye under UV–visible light irradiation for 100 min. The GCRZA composite displayed a better photocatalytic performance against MB dye (90.04%) and RhB dye (83.45%) degradation performance. Moreover, the GCRZA composite PCs exhibited higher photocatalytic activity than pristine g-C3N4. The ultimate photocatalytic property was attained by implementating of g-C3N4/rGO in ZnO-Ag heterostructure, which could effectively decrease the optical bandgap and high visible-light absorption ability with suppressed e?/h+ recombination rate. After the five consecutive photocatalytic recycles, the GCRZA composite PC showed good stability without structural changes. Furthermore, the IC50 values showed that GCRZA nanocomposite (NC) has a higher cytotoxicity effect than g-C3N4/ZnO-Ag, g-C3N4/rGO and g-C3N4 against both HeLa and MCF-7 cell lines. As a result, this combination of nanocomposite has proven to exhibit higher photocatalytic and anticancer activity. Eventually, it may prove to be an effective tool for eradicating dye pollution from wastewater, and a way to prevent cancer mediated diseases in the cosmetics and pharmaceutical industries.
查看更多>>摘要：? 2022 Elsevier B.V.Metal-organic framework (MOF) derived composite is one of the most promising lightweight electromagnetic wave (EMW) absorbers. However, it is still a significant challenge to raise its effective absorbing bandwidth (EAB) for enhancing the EMW absorbing performance. Herein, a novel Co/C composite derived from Co-MOF with a large saturation magnetization was fabricated via a solvothermal reaction and a subsequent annealing process. The resultant Co/C composite shows prominent EMW absorbing performance. The EAB of the Co/C composite obtained at 700 °C reaches an ultra-wide bandwidth of 6.9 GHz at 2.5 mm which is much higher than that of most other MOF-derived composites. The excellent EMW absorbing performance is mainly attributed to the perfect impedance matching, caused by the synergetic effect of dielectric loss and magnetic loss. Hence, this work provides a simple method for the synthesis of MOF-derived Co/C composites with prominent EMW absorbing ability.
查看更多>>摘要：? 2022 Elsevier B.V.The atomic site occupancy of alloying elements in the ZrCo2 and HfCo2 based Laves phases formed in the Co-9Al-9W-2Zr and Co-9Al-9W-2Hf alloys was experimentally determined by the combined techniques of energy-dispersive X-ray spectroscopy mapping with atomic resolution and the atom location by channeling enhanced microanalysis (ALCHEMI) method. The results show that both Al and W occupy the Zr site in the C15 and the Hf site in the C36 crystal structure. The atomic locations of Al and W were further confirmed by comparing calculated inelastic cross-sections with experimental ALCHEMI results. Using the determined atomic site occupancies of alloying elements, special quasirandom structure solid solution models with 192 atoms were constructed and employed in first-principles calculations. It is found theoretically that the energy of formation of the C15 structure is always lower than that of the C36 structure at 0 K in both ZrCo2 and HfCo2 phases, no matter whether Al and W are incorporated or not. However, further ab initio molecular dynamics simulations suggest that lattice vibration at finite temperature contributes significantly to the phase stability, stabilizing the C36 structure compared to the C15 type for the (Hf, Al, W)Co2 phase at finite temperature, which fits well with the experimental findings.
查看更多>>摘要：? 2022 Elsevier B.V.Antimony-based materials with low platform and high theoretical capacity have been considered as a promising candidate of anode material for economical and high-performance potassium ion batteries (PIBs) in the recent decades. Unfortunately, they are still affected by the sluggish kinetics and poor cycle stability, meanwhile, the large radius of the K+ ion leads to the aggregation of particles. Herein, we developed an in-situ perfusing method to construct Sb nanoparticles into the hierarchical porous N-doped carbon (HPNC) microspheres restriction structure, which was proved to be a reasonable and efficient way to enhance the electrochemical properties. Meanwhile, it was acknowledged that electrolyte optimization (KPF6 and KFSI) exerted significant influence on greatly enhancing the electrochemical performance. With the hierarchical porous structure and the electrolyte composition design, Sb@HPNC exhibits an outstanding reversible capacity of up to 507 mA h g?1 at a current density of 0.1 A g?1 over 100 cycles and excellent long-cycle stability of 262 mA h g?1 at 1.0 A g?1 over 700 cycles. We expect this work could offer a reference for the development and exploration of advanced alloy-type electrodes for PIBs.
查看更多>>摘要：? 2022 Elsevier B.V.As a typical two-dimensional layered material, MoS2 has attracted extensive attention owing to its abundant reserves, adjustable electronic structure, and excellent chemical stability. Although MoS2 has unsaturated edge sites with high catalytic activity similar to that of Pt-based materials, its catalytic activity is greatly limited by the high proportion of electrochemically inactive MoS2 basal planes because MoS2 base atoms occupy most of the MoS2 surface and bind with H atoms weakly. In this study, g-C3N4/Fe3O4/MoS2 composite electrocatalysts were synthesized by the growth of MoS2 nanosheets on Fe3O4 sites supported on g-C3N4 substrates. According to our results, the Fe3O4 sites caused MoS2 to form highly dispersed nanosheets and prevented their agglomeration; this realized the high exposure of the catalyst active sites, redistribution of surface charge, and optimization of hydrogen adsorption kinetics and stability. In addition, the performance of the electrocatalytic hydrogen evolution reaction of MoS2 was improved.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, the construction of host referred binding energy (HRBE) diagram and vacuum referred binding energy (VRBE) diagram is described in detail. The energy gap of Zn4B6O13 is calculated by diffuse reflectance spectroscopy and the energy level positions of Eu3+ in VRBE are determined by the charge transfer (CT) band of Zn4B6O13 doped Eu3+ to construct a complete lanthanide ions VRBE diagram. According to the constructed VRBE of Zn4B6O13 system, novel long-afterglow phosphors Zn4B6O13:Mn2+ co-doped with Ln3+ (Ln = Sm, Yb, Eu) is designed and synthesized successfully. The influence of B2O3 contents on the crystal structure and luminescence of the Mn2+ doped zinc borate phosphors were analyzed by XRD and emission spectra. Photoluminescence excitation and emission spectra, persistent luminescence spectra and afterglow decay curve indicate that the doping of lanthanide ions Sm3+ and Yb3+ prolonged the afterglow duration of green emission of Mn2+ effectively. The fitting results of persistent luminescence spectra is consistent with the fast decay process of afterglow decay curve. The energy level depths of Sm3+ and Yb3+ traps obtained by thermoluminescence analysis are 0.49 eV and 1.12 eV respectively, which are in good agreement with the results calculated by VRBE. The energy level position of Sm3+ and Yb3+ below the conduction band (CB) are suitable trap depth, which can store and release electrons continuously. However, that of Eu3+ is too deep to enhance the afterglow. According to the VRBE theory, the mechanism of the electron trap is satisfactorily explained, which is important to the subsequent research of system design and mechanism explanation of lanthanide ions doped long afterglow materials.
查看更多>>摘要：? 2022 Elsevier B.V.A systematic study of the crystal and electronic structure of the intercalation compound AgxZrTe2 in the Ag concentration range of x = 0–0.37 has been performed. It was found that the Ag atoms occupy the sites in the interlayer gap that are tetrahedrally coordinated by the Te atoms. The chemical bond is provided by the Ag 4d/Te 5p hybridization. The comparison of the studied electronic structure with the available data on the electrochemical measurements of AgxZrTe2 in the temperature range of 200–400 °C indicates the formation of covalent centers accompanied by the formation of the half-filled band of Ag 4d/Te 5p hybridized states. The shape of the phase diagram in the region of low Ag concentrations coincides with that observed for AgxTiTe2, in which the stability of the covalent centers is confirmed by the Ag 5s/Ti 3d hybridization. This indicates the universal character of the influence of the localized or extended states of conduction electrons on the phase diagram of intercalation compounds.
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