查看更多>>摘要：? 2022 Elsevier B.V.Morphology design is one effective strategy for improving the rate capability and cycling stability of Fe2O3 anode material for lithium-ion batteries. Herein, a kind of dendritic Fe2O3 architecture was prepared through a hydrothermal route in which glycine molecules guide crystal growth and turn into carbon in the final composite. The special coralloid Fe2O3/NC composite integrates the structure advantages of porous and low-dimensional regular electrode materials. The mutually supportive architecture provides more space to exchange ions with electrolyte and accommodate mechanical stress to suppress volume change, and improves better electron conductivity compared to isolated particles. The Fe2O3/NC delivers 837.6 mAh g?1 at 10 A g?1 and maintains 788 mAh g?1 after a long-term life of 1000 cycles. One more discovery is that the dendritic Fe2O3 architecture grows into needle-like crystals driven by electrode reaction revolved to ion migration and crystal regeneration.
查看更多>>摘要：? 2022 Elsevier B.V.Aqueous zinc-ion hybrid capacitors (ZIHCs) based on a multivalent ion-storage mechanism are attracting increasing attention owing to their inherent safety and low-cost. However, their unsatisfactory energy density and durability have so far limited their practical application. Herein, iron-doped α-manganese dioxide was grown on carbon cloth (FMO/CC) via a facile method to obtaied an aqueous ZIHC cathode. The important role of the iron dopant in modulating the microstructure and assistingg ion diffusion as well as suppressing the overpotential for the hydrogen evolution reaction at the FMO/CC cathode was demonstrated by experimental results and theoretical calculations. Moreover, characterization by ex situ XPS revealed that the Mn4+/Mn3+ and Fe3+/Fe2+ redox couples were involved in the Zn2+ storage mechanism. As a result, the FMO/CC cathode displayed electrochemical performance with a capacity of 288 mAh g?1 at a current density of 1 A g?1, an increased operating voltage range of 1.4 V, and cycling stability with only 15 % capacity loss over 10,000 cycles at 10 A g?1. Moreover, the obtained ZIHC based on an FMO/CC cathode and an activated carbon anode exhibited an energy density of 47 Wh kg?1 and a power density of 995 W kg?1, as well as 72 % capacity retention after 5000 cycles. The excellent electrochemical performances of the FMO/CC cathode demonstrate great potential applications in Zn2+ energy storage devices.
查看更多>>摘要：? 2022Electrocatalytic water splitting is a vastly reliable method for hydrogen production. Nonetheless, its wide practical application urgently requires the development of highly active and stable bifunctional electrocatalysts with self-supported structures. This paper reports on a novel, simple way to fabricate an efficient cobalt/cobalt selenide (CS) catalytic electrode with a unique 3-D finger-like structure. More specifically, porous Co substrate was fabricated by a phase-inversion tape-casting and sintering method, followed by one-step selenization in Ar atmosphere. The resultant CS electrode manifested superior catalytic performance in both HER and OER (hydrogen and oxygen evolution reaction, respectively) that took place in an alkaline medium, with low overpotential and high long-term stability. Furthermore, the electrolysis test for overall water splitting was successfully performed by assembling the CS electrodes as both anode and cathode. The excellent electrocatalytic performance is ascribed to the high conductivity of the Co substrate, the distinctive finger-like structure, and the numerous in-situ developed heterojunctions, which suitably adjust the electronic structure and decrease the energy barrier of water splitting. Moreover, the density function theory (DFT) calculations revealed that the heterojunction enhances the density of the state near the Fermi level and optimize the kinetics of HER and OER processes. As a result, the hydrogen adsorption free energy (ΔGH*) is close to zero, and the energy barrier of the rate-determining step of OER is low due to the heterojunction formed.
查看更多>>摘要：? 2022In the present work, WO3/Ag2S heterojunction was fabricated to achieve an improved photoelectrochemical (PEC) water splitting performance. To prepare the working electrodes, a two-step method was adopted which includes, a thin film of WO3 deposited using DC sputtering and well-separated Ag2S nanorods fabricated by glancing angle deposition. The PEC response was studied for bare WO3, Ag2S, and WO3/Ag2S heterojunction. The as-prepared WO3/Ag2S heterojunction samples revealed higher absorption as well as a higher photocurrent density of 2.40 mA/cm2 (at 1 V Ag/AgCl) as compared to bare WO3 thin film (0.34 mA/cm2). The enhancement in the photocurrent density of WO3/Ag2S electrodes could be ascribed to the formation of the type-II heterojunction between WO3 and Ag2S which effectively separates and transfers the charge carriers at the interface. In addition, increased trapping of light due to vertically tilted Ag2S nanorods structures results in effective absorption of light. Furthermore, electrochemical impedance spectra measurements showed that WO3/Ag2S samples have lower charge transfer resistance at the semiconductor electrolyte interface with high flat band potential. This work provides a deeper insight into the role of the interface formed between WO3 and Ag2S for the photoelectrochemical water splitting response.
查看更多>>摘要：? 2022 Elsevier B.V.Bimetallic hollow nanostructures are of interest for high-performance nanocatalysis and achieving a higher utilization efficiency of noble metals. This paper reports the synthesis of Ag-Pd bimetallic hollow nano-hexagon with outer sizes of about 27 nm and wall thicknesses of 3–5 nm by galvanic replacement reaction (GRR) coupled with a co-reduction method using Ag nanospheres as sacrificial templates. Cetyltrimethylammonium bromide (CTAB) exhibited a double effect on controlling morphologies. First, it acted as the capping agent to mediate the rate of dissolution and deposition on different planes by selectively absorption, and second, it provided Br- ion with ability to promote the GRR. The compositions and structures of Ag-Pd bimetals could be finely tuned by changing the amount of palladium chloride acid (H2PdCl4) while maintaining the volume of Ag seed templates unaltered. By comparing the TOF rate of 4-nitrophenol reduction reaction over different samples of Ag-Pd bimetals as the catalyst, we conclude that hollow bimetallic nano-hexagons with the composition of AgPd0.61 exhibited the highest catalytic activity due to the high surface areas, synergy effect between the two metals, and {100} exposure facets.
查看更多>>摘要：? 2022 Elsevier B.V.As an attractive cathode material, the layered sodium chromium oxide NaCrO2 (NCO) can provide a reversible capacity of around 120 mAh g?1 between 2.0 and 3.6 V, which corresponds to about 0.5 Na per formula is extracted/inserted. However, irreversible phase transition happens in NaxCrO2 when x is less than 0.4 and the potential is exceeding 3.6 V vs. Na+/Na. To improve its high-potential structural stability, Nb5+ is introduced to Cr3+ site by a sol-gel method successfully in this study. The influences of Nb5+ doping on the crystal structure and electrochemical properties are explored. As a result, a more stable structure as well as a higher ionic conductivity are achieved in Na0.94Cr0.97Nb0.03O2 (NCO-Nb3), exhibiting better rate performance and cycling stability between 2.0 and 3.6 V and 2.0–3.7 V. When elevating the charging cut-off voltage to 3.8 V, 4.0 V, 4.4 V, the initial coulombic efficiencies of NCO-Nb3 are still significantly higher than those of pristine NCO.
查看更多>>摘要：? 2022 Elsevier B.V.Lithium metal has garnered increasing attention, and is considered to be the most promising anode material for the next-generation rechargeable batteries with higher energy density such as lithium-sulfur, lithium-air and solid-state batteries. However, several serious challenges limit the commercial application of lithium metal batteries, including uncontrolled lithium dendrite growth, inherent volume expansion, and low Coulombic efficiency. Here, a nitrogen-doped porous nanofiber scaffold decorated with FeNi alloy nanoparticles with high lithophilicity is proposed by the electrospinning technique. The porous structure and the doping of FeNi alloy can expose more lithium nucleation active sites, and effectively reduce the nucleation overpotential of lithium metal to guide the uniform deposition of lithium. The porous structure formed by the sublimation of polymethyl methacrylate can effectively relieve the volume expansion and structural stress during the cycling process. As a result, excellent cycle stability and outstanding rate performance are observed in the tests of symmetric cells, highlighting the feasibility of the designed bimetallic doped carbon fiber scaffold for developing high-performance lithium metal anodes. The present work provides new strategies to solve the formation of lithium dendrites and brings new inspiration for the design and construction of high-efficiency lithium anodes and other secondary batteries anodes.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, LiNi1/3Co1/3Mn1/3O2/Li2FeSiO4/C composite materials were successfully synthesized using the sol-gel method by incorporating carbon derived from the carbonization of citric acid to improve the inherently poor electronic conduction. The material space group was R-3 m, and it did not include any other heterotic peaks. Energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) confirmed the successful formation of a composite material comprising C, Li2FeSiO4 (LFS), and LiNi1/3Co1/3Mn1/3O2 (LNCMO). The initial specific discharge capacity of the LNCMO? 3 composite was 156.4 mAh/g. The capacity retention of LNCMO after 100 cycles was 43.48%, whereas that of LNCMO? 3 was 44.88%. The superior conductivity and chemical stability of the LFS/C layer enhanced the electrochemical performance by improving electron and ion transfer and preventing the attack of electrolytes.
查看更多>>摘要：? 2022 Elsevier B.V.The present lays emphasis on the effect of varying degrees of undercooling on the microstructure development of the Fe50Cu50 alloy system. A sufficiently high undercooling (>100 °C) was achieved using the aerodynamic levitation (ADL) technique whereas a W-wire holding method in the same ADL setups was employed to attain relatively low undercooling (87 °C) during solidification. In addition, solidification experiments were also performed without any undercooling in this alloy system. Thus, the effect of a wide range of undercooling on the phase separation and microstructural development of the Fe-Cu system was systematically investigated in this work. In a substantially undercooled ADL sample, a complete phase-separated micrograph was obtained, but in other situations, a discontinuous network of Cu in interconnected Fe dendritic areas was detected as determined by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) of the sample cross-section confirms that the phases present at the end of the solidification process are α-Fe and Cu, regardless of the degree of undercooling. In the instance of the ADL sample, the entrapment of Cu droplets in the inter-connected Fe dendritic area due to a combination of high undercooling and centrifugal force was detected using X-ray tomography, and the orientation distribution of the samples was determined using Electron Backscatter Diffraction (EBSD).
查看更多>>摘要：? 2022 Elsevier B.V.The fabrication of electronic devices based on zinc oxide (ZnO) for various applications requires a stable and reproducible p-type nanostructure. Herein, a stable atomic layer deposition process is established, and N and F codoped p-type ZnO (NFZO) thin films are deposited on silicon, glass, and polyethylene terephthalate substrates, and Hall effect measurements demonstrate the p-type conductivity with a resistivity of 0.208 Ω?cm, a carrier concentration of 1.84 × 1018 cm–3 and a mobility of 16.27 cm2?V–1?s–1. In addition, the I-V characteristics of a homogeneous and coherent p-n junction consisting of the p-type NFZO and a previously-developed n-type ZnO clearly demonstrate the rectifying nature. Moreover, the potential application of the fabricated light-emitting device in optoelectronics is demonstrated by electroluminescence analysis, with significant emission in the blue region. Finally, the piezoelectric screening effect that compromises the output performance of the piezoelectric nanogenerator is prevented by using the as-developed p-type NFZO.
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