查看更多>>摘要：The influence of novel Cd-Ni co-substituted BiFeO3 (BFO) on structural, magnetic, optical and photocatalytic properties of nanoparticles were studied. Samples were prepared using tartaric acid modified sol-gel technique. Doping-induced structural distortion from rhombohedral to orthorhombic phase was confirmed by XRD and Raman results. The crystallite size decreases from 16.49 to 11.23 nm with increasing the dopant concentration. Morphological studies using HR-SEM revealed that the average particle size decreased significantly from 91.90 to 53.52 nm. EDX studies were used to validate the sample elemental analysis. Furthermore, the effective co-substitution of Cd-Ni into the bismuth ferrite lattice improved the saturation magnetization from 0.096 emu/g to 2.420 emu/g. The XPS confirmed the dominance of the Fe3+ oxidation state. The optical bandgap of BFO nanoparticles could be tuned by Cd-Ni co-doping from 2.06 eV to 1.75 eV. Also, Bi1-xCdxFe1-xNixO3 (BCFNO-6) sample demonstrated the best Methylene blue (MB) and Rhodamine B (RhB) degradation activity under UV-visible irradiation. (C) 2021 Elsevier B.V. All rights reserved.
Martinson, K. D.Belyak, V. E.Sakhno, D. D.Ivanov, A. A....
11页
查看更多>>摘要：Wide practical application and increasing functional requirements for high-frequency ceramics lead to the active search for novel multicomponent ferrites and their synthesis technique. In this paper, a solution-combustion-assisted approach was proposed and realized for the successful production of ultra-magnetically soft LiZnTiMn-ferrite ceramics with advanced electromagnetic performance. Preceramic nanopowders of Li0.28Zn0.16Ti0.41Mn0.10Fe2.05O4 with spinel structure were synthesized via glycine-nitrate combustion at variable Ox/Red ratios (phi = 0.5, 1.0 and 1.5) followed by stabilizing quenching (600 degrees C, 2 h) and vibrating mill grinding. LiZnTiMn-ferrite-based fine ceramics were produced then using PVA binding (1 wt%), isostatic pressing (400 MPa) and Bi2O3-assisted (0.3 wt%) isothermal sintering (980 degrees C, 8 h) techniques. As result, a series of LiZnTiMn-ferrite ceramic samples were obtained and their structure was examined in detail using XRD, SEM, EDXS, AAS and ASA methods. It was shown that the Ox/Red ratio of the initial reaction solution is an efficient parameter affecting both crystallite size (26-38 nm) /crystallinity degree (up to 91%) of pre ceramic LiZnTiMn-ferrite powders and grain size (2.7-9.8 mu m) / grain size distribution of resulting fine ceramics. Based on the results of vibration magnetometry it was found that ceramics samples possess the ultra-magnetically soft behavior with H-c = 0.61-0.89 Oe, M-r = 3.62-5.13 emu/g and M-s = 67.23-78.70 emu/g depending on the initial Ox/Red ratio. Besides, results of resonator analysis (100 Hz 1000 kHz) demonstrate that the dielectric constant of the samples strongly depends on the average grain size and reaches its maximum value (similar to 6.4 10-4) at 100 Hz for the stoichiometric Ox/Red ratio (phi = 1.0) of reagents, wherein the linewidths of ferromagnetic resonance and resonance of spin waves practically unchanged and are in ranges of 327-344 and 1.43-1.45 Oe, respectively. Thus, it was found that the solution combustion synthesis, adapted for fine ceramics production, provides controlling morphological and structural parameters of the pre-ceramic powders through Ox/Red ratio of initial reagents and as consequence, allows variable magnetic and dielectric characteristics of the resulting ceramic products. Developed ceramic materials can be promising for use as a basis for modern radio-electronic devices of both civil and military use. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The introduction of conductive interlayer is an effective strategy to improve the sulfur utilization and restrict the migration of polysulfides for high-performance Li-S battery. Herein, a multifunctional CNT based interlayer was obtained by a simple polyelectrolyte (PDDA-TFSI) modified method. Due to the electro-positivity of PDDA-TFSI and the electronic coupling between CNT and PDDA-TFSI, the CNT/PDDA-TFSI inter layer exhibits a strong adsorption and effective catalysis towards polysulfides. Furthermore, the continuous CNT network ensures the successful electron transport during the charge-discharge process. As expected, the electrochemical properties of Li-S battery can be promoted significantly with the assistance of CNT/ PDDA-TFSI interlayer. Even after 300 cycles, the CNT/PDDA-TFSI interlayer-based Li-S battery also delivers a higher capacity retention of 79.2%, proceeding Li-S batteries with and without CNT interlayer. This work proves that CNT/PDDA-TFSI film as a multifunctional interlayer has a promising application in advanced Li-S battery. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this paper, the ZIF-8/ZnO mixture was sintered at high temperature to prepare C-ZnO composite nano particles with excellent photocatalytic degradation ability under ultraviolet light, and then blended with PVDF to fabricate PVDF composite membrane with capabilities of photocatalytic degradation of methylene blue(MB) via solution phase conversion. The results show that the photocatalytic performance of the prepared C-ZnO composite particles was the best when the ZIF-8/ZnO mass ratio was 1:2, and the photocatalytic degradation efficiency of the PVDF composite film prepared was as high as 95.02% when the composite particle content was 15%. The photocatalytic activity of C-ZnO composite material benefits from the synergy between the two. Moreover, the efficiency of photodegradation of MB remained above 90% after the composite membrane was subjected to five cycles of experiments, which solved the problem that the traditional photocatalyst was difficult to recycle. In addition, it is found that O-2(-) plays a major role in the photocatalytic degradation of MB through free radical capture experiments. All in all, the PVDF composite membrane containing C-ZnO composite particles has a foreseeable potential in the field of photocatalytic printing and dyeing wastewater in the future. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, CuCo2O4/CuO composite microspheres were easily prepared by an initial solvothermal method with a post annealing treatment of precursor in air. The microstructures and electrochemical performances of the electrode materials annealed at 400, 500, and 600 degrees C were investigated in details. It was revealed that the composite microspheres obtained at the annealing temperature of 400 degrees C (CuCo2O4/CuO-40 0) exhibited the best electrochemical properties including a high specific capacity of 279.36 C g(-1) at 1 A g(-1) and a good rate performance with 77.21% capacity retention at 10 A g(-1). In contrast, the CuCo2O4/CuO composite annealed at 500 and 600 degrees C delivered specific capacity of 254.94 C g(-1) and 224.93 C g(-1), respectively. A hybrid supercapacitor (HSC) was assembled with CuCo2O4/CuO composite as cathode and activated carbon (AC) as anode, and the CuCo2O4/CuO-400//AC HSC possessed superior performance such as an energy density of 19.18 W h kg(-1) at 770.41 W kg(-1) as well as 84.36% capacity preservation over 5000 cycles at 5 A g(-1). The present synthetic method is convenient and cost-effective, and can be extended to the preparation of other cobalt-based binary transition metal oxides with excellent electrochemical properties for energy storage and conversion. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：BiVO4 is one of the substrates that have received wide attention from researchers for photoelectrochemical (PEC) water oxidation due to its narrow band gap and sufficiently upbeat valence band. In this study, Mn-FeOOH cocatalyst was synthesized on the BiVO4 photoanode by a chemical bath deposition method at room temperature. As water oxidation cocatalyst, FeOOH could oxidize H2O to O-2 kinetically easier. Furthermore, the Mn element mixing increases the active sites, leading to a faster charge transfer rate by decreasing the kinetics barrier, and it can act as a passivation layer to suppress electron-hole recombination. The results show that the photocurrent density of Mn-FeOOH/BiVO4 is 1.4 mA cm(-2) (1.23 VRHE), which is 2.3 folds that of the bare BiVO4 electrode (0.6 mA cm(-2)), and the onset potential is also negatively shifted by 130 mV and provides a new idea for the design of photoelectrodes. (C) 2021 Elsevier B.V. All rights reserved.
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