查看更多>>摘要：? 2022 Elsevier B.V.Isoelectronic heavy elemental substitutions are generally preferred for enhancing the phonon scattering in a material without deteriorating its electrical transport. In this work, we demonstrate the efficacy and contrasting role of bismuth, an isoelectronic substitute of antimony, for enhancing the thermoelectric transport in structurally ordered cubic VFeSb half-Heusler. Despite its limited solubility, Bi-substitution at Sb-site, was found to be effective in enhancing the electrical power factor near room temperature. Alongside, synergistic lowering of lattice thermal conductivity was observed due to point defect scattering of phonons by Bi-induced mass and strain fluctuations. The electronic transport properties of nominal compositions and effects of Bi-doping induced disorder were evaluated using the Korringa–Kohn–Rostoker method with a coherent potential approximation (KKR-CPA). A highest thermoelectric figure-of-merit (zT) ~0.22 at 478 K was attained with improved weighted mobility and quality factor for optimally doped VFeSb0.98Bi0.02 half-Heusler alloy making them prospective compositions for near room temperature thermoelectric applications.
查看更多>>摘要：? 2022 Elsevier B.V.Co3O4 is an excellent catalyst for the thermal decomposition of ammonium perchlorate (AP) due to its spinel structure and more Co3+ as catalytically active sites. In this work, MCo2O4 (M=Fe, Cu, Ni and Zn) with different Co species substituted with transition metal ion were prepared using triblock copolymer F127 as soft template by simple solvothermal and subsequent heat treatment. The porous MCo2O4 samples have higher Co3+ / Co2+ ratio than Co3O4, and exhibits better catalytic performance for thermal decomposition of AP. Especially with the addition of FeCo2O4, the high decomposition temperature (HDT) of AP decreases by an amazing 196.25 °C, showing the most excellent catalytic performance. The activation energy (Ea) decreases from 290.19 kJ·mol?1 for pure AP to 203.05 kJ·mol?1, while the reaction rate (k) increases from 0.499 s?1 to 1.699 s?1. Based on the electron transfer theory, the catalytic mechanism and active site of porous MCo2O4 series cobaltate materials are discussed. The results show that the porous FeCo2O4 not only has highest specific surface, but also has the highest Co3+/ Co2+ ratio, which suggest that the Co3+ on octahedral coordination sites is known as the catalytic active site for AP thermal decomposition.
查看更多>>摘要：? 2022 Elsevier B.V.Delafossite structure CuFeO2 has attracted researchers’ interest because of its narrow band gap, high stability, low cost and easy availability. However, due to the low efficiency of internal photoinduced charge separation, there is still a gap between its performance and practical application. Herein, a 2D on 2D CuFeO2/Co-LDH heterojunction was prepared by in situ growth method with enhanced charge separation efficiency resulted from the interfacial built-in electric field. Electrochemical and spectroscopic characterization were carried out which illustrated the energy band structure of heterojunction indicating the photoinduced electrons transfer from Co-LDH to CuFeO2. By fine-tuning the amount of precursor, we found that CuFeO2/Co-LDH-3 heterojunction showed the highest photocurrent of 6.07 μA/cm?2, which presented optimal performance of photocatalytic selective oxidation of benzyl alcohol with the average conversion and selectivity of 84.33%, and 98.48%, respectively. This work proposes a preparation method of novel 2D on 2D CuFeO2/Co-LDH heterojunction, which promotes the development of the heterojunction photocatalysts.’
查看更多>>摘要：? 2022 Elsevier B.V.Lithium tetraborate is one of the tissue equivalent material that has been modified with numerous dopant/codopant to improve its Thermoluminescence and Optical stimulated Luminescence properties. Lithium tetraborate doped with Aluminum is being investigated for Optical stimulated Luminescence dosimetry in this paper. Polycrystalline nano-phosphor samples were synthesized using two step solid state reaction method with optimized concentration of Aluminum equals to 2% (by wt.). Formation of the same and its morphology was confirmed using X-ray Diffractometry and Transmission Electron Microscopy. The various dosimetric properties of the obtained phosphor along with related Optical stimulated Luminescence kinetic parameters have been studied. The phosphor exhibits good linearity for gamma radiation in the range of 0.1–500 Gy with other properties such as low fading, satisfactory reusability & reproducibility and minimum detectable dose of 0.05 Gy. In this paper we have also explored the Temperature-Assisted Optical stimulated Luminescence properties of the obtained phosphor in the range of 25 ?C to 200 ?C and the optimized temperature corresponding to the maximum Optical stimulated Luminescence intensity was found to be 125 ?C with activation energy equals to 0.108 ± 0.02 eV. The studied nanophosphor has also shown linear response with dose gamma (1–200 Gy) and beta (0.05–3 Gy) at 125 ?C.
查看更多>>摘要：? 2022 The AuthorsThe increase in the consumption of pharmaceutical compounds has caused the increment of their presence in different body waters. β-blockers are one of the most dangerous even at low concentrations (ng L?1). Anodic oxidation with a boron-doped diamond (BDD) anode presents good results to remove these compounds. However, since this anode is expensive, some cheaper materials are under study. In this work, Sb-doped SnO2 ceramic anodes (BCE) coated with Zn or Cd ferrites, in order to provide photocatalytic properties, have been applied to the degradation of the Atenolol (ATL) β-blocker. Increasing the applied current increased ATL degradation and mineralization but caused a decrease in mineralization current efficiency (MCE) and an increase in energy consumption (ETOC). Additionally, light irradiation enhanced the ATL mineralization rate between 10% and 20% for both ferrites, although this increase was higher for the cadmium ferrite one. Finally, when the ferrites were compared with BDD and BCE anodes, the oxidizing power of the different anodic materials can be ordered as follows BDD> Cd-Fe> Zn-Fe> BCE. Therefore, both ferrites improved the BCE performance but only the cadmium one appeared as an alternative to the BDD, especially for MCE and ETOC, reaching values of 15% and 0.5 kWh gTOC?1, respectively.
查看更多>>摘要：? 2022 Elsevier B.V.For Sc-containing Al-Li alloys, Al3Sc precipitates exhibited inhomogeneous distribution due to limited solid solubility, segregation and sluggish diffusion of Sc. Laser rapid melting (LRM) with its merit of increasing the solubility of alloying elements during solidification represents a pivotal technique for exploring new alloy compositions. In this study, microstructure evolution and aging precipitation behavior of a novel Al-Li-Cu-Mg-Ag-Sc alloy fabricated by LRM were investigated during a systematically optimized T6 heat treatment. No primary Al3Sc particles were formed during the rapid solidification, but coherent Al3Sc nanoparticles were precipitated in the subsequent cooling process. Maximum hardness of 202 HV was achieved after aging at 175 °C/18 h due to combined precipitation strengthening of the Al3Sc, δ', Al3(Li, Sc) and T1 phases. Coherent Al3Sc was concerned with a sequence of atomic displacement modulations that led to varying degrees of {002}Al planar collapse, while interfacial dislocations were emitted from the interface of Al3Sc with coherency lost. The existing Al3Sc phases were available to be acted as nucleation sites for δ′ and T1 to form composite phases. These results can provide indispensable information for compositional design of novel Al-Li alloy specifically for laser additive manufacturing.
查看更多>>摘要：? 2022 Elsevier B.V.Ag2S-ZnS (AZ) heterostructures with tunable aspect ratio (AR) and band structure were successfully synthesized by site-selective doping of metal ions. TEM and XPS results showed that by doping Cu, Mn and Cd ions in AZ heterostructures (Cu: AZ, Mn: AZ and Cd: AZ), respectively, the morphology of AZ heterostructures changed from tadpole-shape (Cu: AZ with AR of 1.2) to matchstick-shape (Cd: AZ with AR of 3.9) due to the selective doping of Cu ions in Ag2S head and Cd ions in ZnS tail as well as the doping of Mn ions both in Ag2S head and ZnS tail (Mn: AZ with AR of 2.7). All the UV-Vis spectra of doped AZ showed Urbach tail absorption, suggesting the existence of midgap-states created by metal ion dopants, which was confirmed by PL results. Cd: AZ with the largest AR values and Cd-doping induced midgap states showed the highest photocatalytic H2-production rate of 1443.55 μmol h?1 g?1. The catalytic activity of the Cd: AZ can be ascribed to the synergistic effect of midgap states and aspect ratio-dependent charge transfer, which all originate from the site-selective doping of metal ions. This investigation demonstrates a facile way to manipulate the charge carrier dynamics of semiconductor heterostructures by synergistic effects through simultaneously tuning and optimizing the electronic and morphological structures.
查看更多>>摘要：? 2022 Elsevier B.V.Nonlinear optical (NLO) crystals, have attracted intense attentions in many related fields. Herein, we report a noncentrosymmetric (NCS)-centrosymmetric (CS) structure correlation between two semiorganic nitrates: C6H14N2(NO3)3·H3O (1,4-diazoniabicyclo-octane oxonium trinitrates, DHN) vs C6H14N2(NO3)2 (1,4-diazoniabicyclo-octane dinitrates, DN). Our single crystal data confirm the DHN structure as previously reported and we find that DHN changes to DN by heating at 125 °C for 5 h. In addition, the comprehensive NLO optical properties of DHN are studied: large birefringence (obv.: 0.110 at 589.3 nm), laser damage threshold (obv.: 2.5 × KDP), a phase matching behavior with the maximum intensity of 1.60 × KDP. Our first-principles calculations suggest that the NO3? anions contribute mainly to the band gap and to the second-harmonic generation (SHG). In addition, we reveal the detonation properties of DHN that are comparable to TNT: density (ρ) = 1.67 vs 1.65 g cm?3; detonation velocity (D) = 7.09 vs 6.66 km s?1; and detonation pressure (P) = 23.3 vs 21.3 GPa.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, we report on the Czochralski growth and optical characterization of Pr:LGSB as a new nonlinear optical (NLO) and laser crystal. Single crystals of Pr:LGSB were grown by the Czochralski method, for the first time to the best of our knowledge, from the starting melt compositions La0.656Pr0.022Gd0.572Sc2.75(BO3)4 and La0.651Pr0.027Gd0.572Sc2.75(BO3)4. The crystal growth parameters were optimized and two Pr:LGSB crystals with good optical quality were obtained. The chemical compositions of the grown crystals were determined to be La0.750Pr0.020Gd0.450Sc2.780(BO3)4 and La0.743Pr0.025Gd0.452Sc2.780(BO3)4 corresponding to a Pr3+ ions concentration in the crystals of 2.0 at% and 2.5 at%, respectively. The spectroscopic properties were investigated and the obtained results show that the 2.5 at% Pr:LGSB is a promising laser crystal emitting in the orange spectral range at ~ 603 nm. The refractive indices were measured and the phase-matching curves for type I and type II SHG were determined. The walk-off angle, the external angular acceptance, and the nonlinear coefficient d11 for type I SHG of 603 nm fundamental wavelength were also evaluated. This work shows that the 2.5 at% Pr:LGSB crystal could be a new promising candidate for obtaining laser sources in the UV range (~ 301.5 nm) in SFD configuration.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, a nanosheet-assembled core-shell structure composite of Co-Ni-S@CoNi-LDH was prepared on Ni foam via hydrothermal synthesis, in which Co-Ni-S nanowires as cores were assembled with the shell of CoNi-LDH nanosheets. The combination of the high conductivity of Co-Ni-S, the high specific surface area of CoNi-LDH and the multivalent state of Ni and Co provided more active sites, short and effective ion transport paths, and great synergy, which played significant roles in the excellent performance of Co-Ni-S@CoNi-LDH. Meanwhile, the nanosheet-assembled core-shell structure improved the overall stability. Based on the characterisation and the performance measurements, the Co-Ni-S@CoNi-LDH electrode showed an excellent electrochemical performance. The Co-Ni-S@CoNi-LDH electrode acquired a specific capacitance of 2414 F/g at a 1 A/g current density and a high cycle stability with an 89.7% retention after 3000 cycles. The assembled hybrid supercapacitor Co-Ni-S@CoNi-LDH//AC delivered a high energy density of 59.11 Wh kg?1 at an 855.43 W kg?1 power density, as well as an excellent rate performance of 81% after 5000 cycles at a 5 A/g current density, showing good potential for practical applications.
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