查看更多>>摘要：? 2022 Elsevier B.V.Electrochemical properties of spinel LiMn2O4 still suffer from notorious Mn dissolution and Jahn-Teller distortion. Herein, a series of LiAl0.1NixMn1.90-xO4 (x = 0–0.10) cathode materials were prepared via a facile solid-state combustion combined with elements doping and morphology controlling strategy. All as-prepared samples possess a good spinel structure without any impurity. Rietveld refinements results illuminate that Al,Ni co-doping gives rise to the shrinkage of MnO6 octahedron and expansion of LiO4 tetrahedron, thereby improving the structural stability and restraining the Jahn-Teller distortion of the LiMn2O4. The Al,Ni co-doped spinel LiMn2O4 exhibits truncated octahedral particles with well-developed crystal facets of (111), (110) and (100), in which (111) facets suppress the Mn dissolution, while (110) and (100) facets boost Li+ ions diffusion. Consequently, the truncated octahedral LiAl0.1Ni0.03Mn1.87O4 sample delivers high discharge capacity and long cycled stability. At relatively high current rates of 10 C, 15 C and 20 C, the initial discharge capacities of 100.2, 96.1 and 92.9 mAh/g are achieved, the corresponding capacity retention ratios are 82.4%, 79.0% and 74.9% after 1000 cycles, respectively. This work will lay a certain foundation for the development of high-performance lithium-ion batteries in the future.
查看更多>>摘要：? 2022 Elsevier B.V.The g-C3N4 (CN) microrods with superficial C, N dual vacancies were synthesized by facial thermal polymerization of melamine--cyanuric acid supramolecular (MCS) precursors under H2 flow. Compared with bulk g-C3N4 (BCN), the as-synthesized defective CN microrods with an increased specific surface area exhibit an enhanced photocatalytic performance with a kinetic constant (K) of ~0.19 min?1 for RhB degradation and an ~718.36 μmol g?1h?1 for H2O2 production rate, which are about~17-fold and ~3-fold higher than that of BCN, respectively. The C, N dual vacancies are very effective in reducing the bandgap and inhibiting carrier recombination. The pivotal active species in RhB degradation is determined to be·O2-, and the pathway of H2O2 production is confirmed as a sequential two-step single-electron reduction. The results have provided a great potential way to promote the practical application of CN for photocatalytic organic pollutant removal and H2O2 production.
查看更多>>摘要：? 2022 Elsevier B.V.The combination of high optical transparency and radiation shielding effectiveness of zinc sodium borate glasses by tungsten oxide additions has been investigated. We investigated glasses of a formula [xWO3–(25-x)-ZnO-20Na2O–55B2O3; where 0 ≤x ≤ 20, step= 5 mol. %], based on their structural, optical and radiation shielding properties. Actually, five different glass samples were synthesized using the melt quenching approach. The transmittance of all glass samples was measured via a spectrophotometer in the wavelength range from 300 to 1100 nm. The transmittance results confirmed the increased transparency of the investigated glasses with further WO3 additions. Moreover, the transmittance results indicated the absence of W5+, W4+, W3+ states; based on the absence of their absorption bands. Furthermore, these transmittance results revealed that the only oxidation state in the present glasses is the hexavalent tungsten (W6+) that belongs to the d° electronic configuration. The refractive index (n0) and nonlinear refractive index (n2) were determined and showed an increasing behavior with further WO3 doping. Also, the additions of WO3 resulted in an increasing behavior in the linear attenuation coefficient values with a decreasing one in the half-value layer of the current glasses. These outcomes declare that the current glasses are good candidates for radiation shielding purposes.
查看更多>>摘要：? 2022 Elsevier B.V.Tuning the morphology of the semiconductor heterojunction photocatalyst has attracted extensive attention for effective photocatalytic performance in the process of wastewater treatment. The combination of boron doped reduced graphene oxide (B-rGO) supported by Bismuth ferrite (BiFeO3) nanocomposite was fabricated via simple one-pot mild hydrothermal synthesis. Notably, the non-metal doping with reduced graphene oxide leads to an extra advantage in improving photophysical properties such as electrochemical impendence spectroscopy (EIS) and photocurrent measurements, which significantly increases the charge carrier recombination factor due to the density state value near to the Fermi energy level in the system. The intimate layer contact between the B-rGO and BiFeO3 nanocomposite is well established by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (UV-DRS), and Vibrating sample magnetometer (VSM). Furthermore, scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) provide clear evidence for decorating hierarchically layered nanocomposite. The superior performance of the developed nanocomposite degradation efficiency was revealed towards Tetracycline (TC), and Rhodamine B (RhB) was chosen as an ideal model pollutant. The degradation efficiency was achieved for TC (86.7%) and RhB (99.4%). Also, the developed photocatalyst exhibited excellent photostability after four consecutive stability cycles. Finally, the non-metal doping technology was found to demonstrate excellent potential features in the field of environmental wastewater and pharmaceutical water detoxication.
查看更多>>摘要：? 2022 Elsevier B.V.Er3+-doped Bi2O3 thin films were sputter-deposited on SiO2 substrates under various process conditions. After post annealing in an O2 atmosphere, near-infrared photoluminescence (PL) spectra from Er3+ ions in specific product oxides were observed. For sufficiently oxidized Bi2O3:Er films with Er contents less than 1.5 at%, α-Bi2O3:Er having a monoclinic structure nucleated with negligible intermixing of the elements across the interface. Its PL spectra exhibited Er3+ luminescence signals consisting of eight Stark splitting peaks. Deposition at temperatures higher than 400 °C and/or with high Er content produced a somewhat reduced Bi2O3 network. Post annealing triggered diffusion of Si into the film as well as diffusion of Bi and Er into the SiO2 substrate, creating Bi2O3 ?SiO2 ?Er2O3 compound oxides. The original film body crystallized into a δ-Bi2O3 structure, which was stabilized by the presence of a large amount of Er. The emission-active product at Er contents of 2 at% was Bi2O3:Er?SiO2 (Bi2SiO5:Er), which exhibited four-line emission spectra and the intensity was lower than that of α-Bi2O3:Er. For Er3+ contents higher than 4 at%, interdiffusion of Si and O atoms was enhanced and SiOx:Er domains were created in the Bi2O3:Er film. Intense and broad emission peaks at 1530 and 1560 nm were observed in the PL spectra. The emission-active species in the Bi2O3 ?SiO2 ?Er2O3 compound oxide will be either Er3+ doped in the strongly disordered δ-Bi2O3 lattice involving oxygen deficiencies or Er3+ attached to SiOx domains formed inside the δ-Bi2O3 network.
查看更多>>摘要：? 2022 Elsevier B.V.Microstructural evolution and mechanical properties of a Mg?8Zn?6Al?1Gd (wt%) alloy were thoroughly investigated in this work. The results indicate that the dominant intermetallic phases in the as-cast sample are ?-Al2Mg5Zn2, τ-Mg32(Al,Zn)49, i-Mg44Al15Zn41 and Al2Gd phases and almost free Gd was detected in the former three phases. After extrusion, the sample has a fully recrystallized microstructure with the average grain size being ~1.5 μm, and exhibits a weak rare earth texture. Additionally, fine particles were approximately homogeneously dispersed in the fine-grained structure. Most of them are quasicrystal phase (i-phase) but have no identical orientation relationship with Mg matrix regardless of whether they distribute at grain boundaries or inside grains. Finally, the as-extruded sample exhibits good strength-ductility balance in both tension and compression and simultaneously has a slight reverse tension/compression asymmetry. Microstructural observations indicate that the excellent mechanical performance of the studied alloy is highly related to its fine grains, weak RE texture, and numerous homogeneously distributed fine particles.
查看更多>>摘要：? 2022 Elsevier B.V.NiO and Co1.29Ni1.71O4 were generated in situ by oxidizing and calcining NiCo LDH (Layered Double Hydroxide) to erect an S-scheme heterojunction heterogeneous catalyst. After calcination, the lamellar structure of NiCo LDH becomes thinner and part of the lamellar porous, which can provide more active sites for hydrogen precipitation reaction. The amount of hydrogen released by the composite catalyst is 3 times that of NiCo LDH This in-situ generation method will allow NiO and Co1.29Ni1.71O4 to establish a close relationship, form a built-in electric field, and build an S-scheme heterojunction. NiO and Co1.29Ni1.71O4 have good band structure and band gap position matching. S-scheme heterojunction composite catalyst has the best light absorption intensity and photocurrent response, the smallest electronic impedance, and good electron and hole separation efficiency, thereby improving the performance of photocatalytic hydrogen evolution. It was confirmed by a large number of characterization studies.
查看更多>>摘要：? 2022 Elsevier B.V.Electrochemical conversion of CO2 into renewable fuel offers a promising approach to address the rising greenhouse gas accumulation in the atmosphere. The exploration of low-cost and efficient electrocatalysts with high selectivity is of great importance for development of electrochemical CO2 reduction (ECO2R). Here, we presented a CuNi alloy catalyst embedded in the N-doped carbon framework (CuNi/NC) derived from a metal-organic framework (Cu/Ni/Zn-MOF). The optimized Cu0.543Ni1/NC achieved high Faraday efficiency of CO (>90%) in the wide potential range of ? 0.3 V to ? 0.8 V. The maximum efficiency of CO was 99.7% at ? 0.6 V. This study provided a strategy to construct non-precious metal electrocatalysts with high CO selectivity in wide potential range.
查看更多>>摘要：? 2022 Elsevier B.V.Developing low-cost, efficient and sustainable utilization of visible light catalysts to eliminate antibiotic and heavy metals contaminants simultaneously remains a huge challenge. Herein, a unique CoO/Bi2WO6 p-n heterojunction was successfully synthesized by a facile and simple solvothermal method for simultaneous elimination of tetracycline and Cr(VI) under visible light irradiation. Benefiting from p-n heterojunction following Z-Scheme pathways, 30 wt% CoO/Bi2WO6 heterojunction displayed the best photocatalytic activity for tetracycline degradation (90.7%) and Cr(VI) reduction (57.5%) singly after 90 min reaction. The reaction rate constant for CoO/Bi2WO6 heterojunction towards tetracycline degradation and Cr(VI) reduction were 0.02607 min?1 and 0.00909 min?1, which are 4.23, 4.92 times of pure CoO and 3.46, 4.61 times of pure Bi2WO6, respectively. It is related to the formation of p-n heterojunction, which avoids the agglomeration induced inactivation, extends the spectral response and facilitates the separation and utilization of charge carriers. More interestingly, the higher photocatalytic efficiencies are achieved to simultaneously eliminate the mixed tetracycline and Cr(VI), which are 1.03 and 1.76 times that of single tetracycline and Cr(VI), respectively. Moreover, the 30 wt% CoO/Bi2WO6 heterojunction photocatalyst can be reused for ten cycles and exhibits satisfactory properties of stableness and reusability. Furthermore, the possible reaction pathway and photocatalytic mechanism for TC degradation and Cr(VI) reduction were revealed based on capturing experiments of active species, electron spin resonance and liquid chromatography mass spectrometry. These findings provide a great promise of CoO/Bi2WO6 p-n heterojunction photocatalyst in mixed contaminants remediation.
查看更多>>摘要：? 2022 Elsevier B.V.Core-sheath heterostructures composed of MnCo2O4 nanowires wrapped by nanosheets of NiCo-layered double hydroxide (NiCo-LDH) have been obtained on nickel foam (NF) substrate (MnCo2O4@NiCo-LDH/NF). In which, the MnCo2O4 nanowires play role as core structure, while interconnected NiCo-LDH nanosheets acts as the sheath material. The fabrication is achieved by coupling hydrothermal preparation with electrochemical deposition. This heterostructure combines the advantages of interconnection among NiCo-LDH nanosheets, the high conductivity of MnCo2O4, with excellent mechanical strength and 3D open structure of NF. Benefiting from the core-sheath heterostructures and the interaction among these multi-component, when the MnCo2O4@NiCo-LDH/NF composite is utilized as cathode material for supercapacitors, it delivers a superior specific capacitance of 4555.0 F g?1 at a current density of 1 A g?1 and maintains a capacitance of 78.7% after 5000 successive charging-discharging cycles using 6M KOH aqueous as electrolyte. In addition, the composite has been used as electrode for assembling the MnCo2O4@NiCo-LDH/NF//AC quasi-solid-state asymmetric supercapacitor (ASC) using active carbon (AC) as counter electrode. Such an ASC exhibits an outstanding energy density of 21.3 W h kg?1 at a power density of 160.0 W kg?1 and can light up the green LED indicator for more than 30 min, showing promising prospect for practical applications.
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