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Efficiency and Quality Issues in the Production of Black Phosphorus by Mechanochemical Synthesis: A Multi-Technique Approach
摘要： Black phosphorus (BP) is a two-dimensional material potentially of great interest for applications in the fields of energy, sensing, and microelectronics. One of the most interesting methods to obtain BP is the conversion from red phosphorus (RP) by means of high-energy mechanochemical synthesis. To date, however, this synthesis process was not well characterized. In this work, starting from the mathematical model of energy transfer during the ball milling process, we investigate the effects on RP → BP conversion of three experimental parameters, the rotation speed, the milling time, and the weight ratio between the spheres and the milled material (BtPw ratio). The efficiency of the conversion process was verified by solid-state NMR, Raman spectroscopy, and X-ray diffraction. Whereas the first two parameters have a minor importance, the BtPw ratio plays a primary role in the RP → BP conversion. Yields approaching 100% can be obtained also with short milling times (15 min) and adequate rotation speed (e.g., 500 r.p.m.), provided that the BtPw ratio >40:1 is used. These results confirm the energy sustainability of the mechanochemical synthesis approach.
关键词： diffraction,solid-state NMR,anode,post-lithium ion batteries,Raman,mechanochemical synthesis
更新于2025-11-21 11:18:25
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Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage
摘要： Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.
关键词： dealloying,anode,lithium ion batteries,nanoporous,germanium
更新于2025-09-23 15:23:52
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - High performance x-ray source using point-typed CNT field emitter
摘要： The high performance cold cathode x-ray source was fabricated by using the point-typed CNT field emitter. The cold cathode x-ray source consists of the CNT point emitter, the metal mesh gate electrode, the metal hole focusing lens and the tungsten target anode electrode. To fabricate x-ray source, such components were mounted in a SUS vacuum chamber. The fabricated CNT x-ray source showed a good resolution of x-ray images at a low anode current and at a low anode voltage, and also indicated stable operation. We evaluated x-ray images according to the tube voltage and the tube current, respectively.
关键词： point-typed field emitter,carbon nanotube field emitter,metal mesh gate electrode,x-ray image,cold cathode x-ray source,tungsten anode electrode
更新于2025-09-23 15:21:21
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rGO based photo-anode in dye-sensitized solar cells (DSSC) and its photovoltaic characteristics
摘要： On the attempt to increase transport properties of the photo-anode in DSSC, we synthesized rGO powder from graphite bar (commercially available) using modified Hummer’s method. The SEM-EDS results had confirmed the attachment of the rGO layer to the FTO substrate. For DSSC cells, we made two cells configuration, the first one was stacking layers of rGO and TiO2 resulting configuration of TiO2/rGO/ TiO2 (A2) and rGO/TiO2/rGO (A3), where rGO was deposited by spin coating and TiO2 was deposited by a screen printing technique. The second one, the rGO powder was mixed with TiO2 paste with several ratios in weight, namely TiO2:rGO 40:1 (B1), 40:2 (B2), and 40:8 (B3) and then deposited on the FTO substrate by screen printing. The reference cell was assigned as A1 (TiO2 only). From the conductivity measurement using the four-probe method, the utilization of rGO layer increased the conductivity of photo-anode layer, namely (1.37, 2.9 and 6.3)x10-2 Ω-1cm-1 for A1 to A3 and (1.5, 2.5, and 3.7)x10-2 Ω-1cm-1 for B1 to B3. From the photovoltaic measurement, we found that the efficiency of the DSSC cell firstly increased with the insertion of rGO layer, from 1.8% (A1) to 4.59% (A2), and decreased to 3.22%, as the conductivity increased in A3. While for the composite of TiO2:rGO, the efficiency of the cell reduced with the increased amount of rGO, from 3.45% (B1) to 2.9% and 1.9% for B2 and B3. We found that the reduction of photovoltaic performance was affected by two main factors, specifically, direct contact between rGO and redox species in the electrolyte, which induced recombination process, and conductivity of the photo-anode layer. To fully achieve the advantage of rGO utilization in photo-anode, once must be considered was the use of protection layer on top of the rGO layer to avoid direct contact between the rGO/electrolyte interface.
关键词： photovoltaic,rGO,efficiency,photo-anode,DSSC,conductivity
更新于2025-09-23 15:21:01
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Formation of Si Hollow Structures as Promising Anode Materials through Reduction of Silica in AlCl <sub/>3</sub> –NaCl Molten Salt
摘要： Hollow nanostructures are attractive for energy storage and conversion, drug delivery, and catalysis applications. Although these hollow nanostructures of compounds can be generated through the processes involving the well-established Kirkendall effect or ion exchange method, a similar process for the synthesis of the pure-substance one (e.g., Si) remains elusive. Inspired by the above two methods, we introduce a continuous ultrathin carbon layer on the silica nano/microstructures (St?ber spheres, diatom frustules, sphere in sphere) as the stable reaction interface. With the layer as the diffusion mediator of the reactants, silica structures are successfully reduced into their porous silicon hollow counterparts with metal Al powder in AlCl3?NaCl molten salt. The structures are composed of silicon nanocrystallites with sizes of 15?25 nm. The formation mechanism can be explained as an etching?reduction/nucleation?growth process. When used as the anode material, the silicon hollow structure from diatom frustules delivers specific capacities of 2179, 1988, 1798, 1505, 1240, and 974 mA h g?1 at 0.5, 1, 2, 4, 6, and 8 A g?1, respectively. After being prelithiated, it retains 80% of the initial capacity after 1100 cycles at 8 A g?1. This work provides a general way to synthesize versatile silicon hollow structures for high-performance lithium ion batteries due to the existence of ample silica reactants and can be extended to the synthesis of hollow structures of other materials.
关键词： carbon interface,hollow structures,silicon,molten salt,anode
更新于2025-09-23 15:21:01
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One-pot Hydrothermal Synthesis of ZnO Microspheres/Graphene Hybrid and its Electrochemical Performance
摘要： In this paper, the ZnO microspheres/graphene hybrids were successfully prepared from zinc acetate and GO aqueous solution by a facile one-pot hydrothermal method without any surfactant. The as-synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermogravimetric (TGA) analysis, nitrogen adsorption/desorption isotherms and pore size distribution. When evaluated as anode material for lithium ion batteries, it delivered a high initial discharge capacity of 1150 mAh g-1 and exhibited excellent rate performance at different current densities.
关键词： anode materials,ZnO microspheres/graphene hybrid,one-pot hydrothermal,lithium ion batteries
更新于2025-09-23 15:21:01
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Mechanistic Origin of the High Performance of Yolk@Shell Bi2S3@N-Doped Carbon Nanowire Electrodes
摘要： High-performance lithium-ion batteries are commonly built with the heterogeneous composite electrodes that combine multiple active components for serving various electrochemical and structural functions. Engineering these heterogeneous composite electrodes toward drastically improved battery performance is hinged on a fundamental understanding of the mechanisms of multiple active components and their synergy or tradeoff effects. Herein, we report a rational design, fabrication, and understanding of yolk@shell Bi2S3@N-doped mesoporous carbon (C) composite anode, consisting of a Bi2S3 nanowire (NW) core within a hollow space surrounded by a thin shell of N-doped mesoporous C. This composite anode exhibits desirable rate performance and long cycle stability (700 cycles, 501 mAhg-1 at 1.0 Ag-1, 85% capacity retention). By in-situ transmission electron microscopy (TEM), X-ray diffraction, and NMR experiments and computational modeling, we elucidate the dominant mechanisms of the phase transformation, structural evolution, and lithiation kinetics of the Bi2S3@C NW anode. Our combined in-situ TEM experiments and finite-element simulations reveal that the hollow space between the Bi2S3-NW core and carbon shell can effectively accommodate the lithiation-induced expansion of Bi2S3-NWs without cracking C shells. This work demonstrates an effective strategy of engineering the yolk@shell-architectured anodes and also sheds light onto harnessing the complex multistep reactions in metal sulfides to enable high-performance lithium-ion batteries.
关键词： multiple computational modeling,lithiation mechanism,in-situ experiments,yolk@shell composite anode,lithium-ion battery
更新于2025-09-23 15:21:01
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The Effect of Ir Content on the Stability of Ti/IrO <sub/>2</sub> -SnO <sub/>2</sub> -Sb <sub/>2</sub> O <sub/>5</sub> Electrodes for O <sub/>2</sub> Evolution
摘要： Ternary IrO2-SnO2-Sb2O5 is among the best electrocatalysts for O2 evolution. Its compositions, especially its Ir content, have significant impacts on the electrochemical stability, activity, and cost of the electrode. In this paper, the effects of Ir content on the electrochemical stability and activity of the Ti/IrO2-SnO2-Sb2O5 electrodes were investigated. Experimental results show that the electrochemical stability initially increased with nominal Ir content until 10 mol%. From 10–30 mol%, the effect of Ir composition gives insignificant difference. Further increase in Ir content beyond 30 mol% resulted in a decrease in the electrochemical stability. The performance of the electrode depends on all the steps it was made with about 15 % variation observed at Ir content of 20 mol%, where the longest average accelerated service life was found to be 1063 h under the conditions of anodic current density of 10 000 A/m2 in 3 mol/L H2SO4 electrolyte at 70 oC. The study on electrode degradation and failure mechanism reveals that the development of cracks or pores in the coating surface, the loss of Sb and Ir contents, and crystalline structure change of the coating during the life test facilitated the deactivation of the electrode. Moreover, the non-conductive TiO2 interlayer formation was found to be responsible for the peeling of the coating layer, leading to the failure of Ti/IrO2 -SnO2-Sb2O5, especially with high Ir content (> 30 mol% in nominal).
关键词： metal oxide anode,electrochemical process,DSA,electrode stability
更新于2025-09-23 15:21:01
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Controllable nitrogen doping and specific surface from freestanding TiO2@carbon nanofibers as anodes for lithium ion battery
摘要： Further modification of carbon and transition metal composites has become a hot spot in the preparation of anode materials for lithium ion battery, including various morphologies, nitrogen doping and porous introduction. However, the synergistic effect of specific surface area and nitrogen doping content of composite materials on the electrochemical performance as anode materials for lithium ion batteries has not been revealed. In this paper, the carbon nanofibers loaded with titanium dioxide are fabricated via electrospinning method followed by calcination process with simple addition admixture of diisopropyl azodiformate in precursor solution. The pores are introduced into the composite with controllable nitrogen doping and surface area simultaneously. The specific capacity of titanium dioxide @carbon nanofibers has been increased from 192.2 mAh g?1 to 336 mAh g?1 due to the increased nitrogen content of the composite from 7.18% to 10.21%, and elevated specific surface area from 67.23 to 111.15 m2 g?1, which can endow the composite superior conductivity and more active sites. The capacity contribution of the total specific capacity has decreased from 60.8% to 44.7% compared with original sample, proving that increasing diffusion controlled Faradaic Li-ion insertion origins from nitrogen doping.
关键词： Lithium battery,Porous carbon nanofibers,Nitrogen doping,Anode
更新于2025-09-23 15:19:57
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Ultrasensitive Field‐Effect Biosensors Enabled by the Unique Electronic Properties of Graphene
摘要： Using Li metal-free anodes for lithium-ion oxygen and lithium-ion sulfur batteries is considered as a promising solution to resolve the hazard of Li metal anode. Although Si anode exhibits high capacity and low electrochemical potential, it cannot match with oxygen (or sulfur) cathode, because both lack cycleable lithium ions. In this work, a free-standing and fibrous Si/C anode is prepared by electrospinning and its simple but effective lithiation is proposed. When assembling the cells, the free-standing Si/C anode was put between mass-controlled lithium metal foil and separator, and then the Si/C anode could be lithiated after adding electrolytes. By optimizing a LiFSI based ether electrolyte, the Si/C anode could achieve good cycleablity comparable to that in carbonate electrolytes. The lithiated SieO2 cells exhibit better cycling stability than the lithium oxygen cells with gel polymer electrolye. Moreover, because both Si anode and S@pPAN cathode are compatible with carbonate electrolytes, exceptional cycling performance has been achieved for the lithiated SieS cells. This simple method could pave the way to commercial applications of lithium-ion oxygen and lithium-ion sulfur batteries.
关键词： Lithium-sulfur battery,Lithium-oxygen battery,LieSi alloy anode,In-situ lithiation,Fibrous Si/C anode
更新于2025-09-19 17:13:59