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1.
《Ceramics International》2020,46(5):5811-5820
Nano-porous carbon materials derived from various natural plants are fabricated by a facile, cost-effective and efficient approach. The influence of well-dispersed intrinsic elements in different precursors and chemical activation process under different temperatures on the morphology, surface chemistry, textural structures and electrochemical performance have been studied and analysed in detail. These as-prepared nano-porous carbons possess high accessible surface area (685.75–3143.9 m2 g−1), well-developed microporosity and high content of naturally-derived heteroatom functionalities (16.43 wt%). When applied as electrode materials for supercapacitors in a three-electrode system with 6 M KOH, the obtained nano-porous carbons derived from lotus leaves at 700oC possess a high specific capacitance of 343.1 F g−1 at 0.5 A g−1 and a capacitance retention of 96.2% after 10000 cycles at 5 A g−1. The assembled symmetrical supercapacitor presents a high energy density of 24.4 Wh kg−1 at a power density of 224.6 W kg−1 in Na2SO4 gel electrolyte. This work provides guiding function for unified and large-scale utilization of agricultural biomass waste. The obtained sustainable activated carbon products can be used in diverse applications.  相似文献   

2.
Crystallized anthaxanthin was prepared through the cleaning crystallization method and the stabilities during thermal, lighting, and pH treatment, and antioxidant activities in vitro were evaluated. The structural characterizations of astaxanthin crystal were verified by 1H, 13C NMR, and XRD analysis. The stability data showed that the astaxanthin crystal was more sensitive to heat, light, and pH compared to oleoresin. The sucrose had no outstanding influence on the astaxanthin crystal, while the stability of astaxanthin oleoresin slightly increased with the increase of sugar concentration. The XRD and nuclear magnetic resonance spectra elucidated that the astaxanthin crystal was all trans structure. The astaxanthin crystal showed the dominant 1,1′-diphenyl-2-picrylhydrazyl (IC50 18.65 μmol L−1), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt˙+(21.1 μmol L−1), •OH (IC50 49.46 μmol L−1) and ferric reducing antioxidant power (IC50 81.60 μmol L−1) activities. The investigated results would be helpful for improving the development of astaxanthin crystal in food products.  相似文献   

3.
Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na+ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS2 nanoparticles encapsulated in biphase TiO2 shell (FeS2@TiO2), is developed towards the improvement of sodium storage. The diphase TiO2 coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS2 caused by the Na+ insertion. The FeS2 core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS2@TiO2 nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g−1 at 0.2 A·g−1 after 300 cycles, 374.9 mA·h·g−1 at 5.0 A·g−1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g−1 at 10 A·g−1). Furthermore, the synthesized FeS2@TiO2 demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na+ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.  相似文献   

4.
《Ceramics International》2023,49(10):15793-15801
The degradation of the cobalt-zinc oxide structure and its poor conductivity during the charge and discharge limit their further applications for lithium ion storage. Herein, ZnCo2O4@carbon nanofiber composite with nano-fibrous structure is obtained by electrospinning, annealing in argon and low-temperature oxidation to effectively overcome the above issue. The active sites of ZnCo2O4 are evenly dispersed inside the carbon nanofibers, which can effectively avoid its aggregation and improve electrical conductivity. Additionally, the stable nanofibrous structure can maintain structural stability. The composite exhibits superior lithium ion storage capacity when being served as anode electrode. The ZnCo2O4@carbon nanofiber electrode possesses a high capacity of 1071 mA h g−1 at 0.1 A g−1. Besides, the electrode shows an outstanding rate capability of 505 mA h g−1 at 3 A g−1 and maintain 714 mA h g−1 after 250 cycles when current density is adjusted to 0.2 A g−1 again. Additionally, the electrode has an outstanding long-cycle performance, which remains a capacity of 447.165 mA h g−1 at 0.5 A g−1 after 500 cycles and 421.477 mA h g−1 at 1 A g−1 after 518 cycles. This result demonstrates that ZnCo2O4@carbon nanofiber composite has potential application prospects in the fields of advanced energy storage.  相似文献   

5.
《Ceramics International》2019,45(16):19799-19807
Na2MnPO4F has drawn worldwide attention as cathode materials for sodium-ion batteries with great promise due to its high theoretical capacity (124 mAh g−1) and working voltage plateau (3.6 V). Unfortunately, its electrochemical performances are largely limited by the intrinsic low electron conductivity and sluggish diffusion of Na+. Herein, a reduced graphite oxide nanosheets and nano-carbon co-modified Na2MnPO4F nanocomposite is prepared via a simple hydrothermal method. And the composite possesses a three-dimensional “pellets-on-sheets” structure, in which core-shell structured nanoparticles (Na2MnPO4F nanoparticles coated by carbon coating layers) are uniformly anchored on the surface of well-dispersed reduced graphite oxide nanosheets. Such unique structure is favorable for fast Na+ and electron transports and supplies sufficient active sites for Na+ insertion. As the cathode of sodium-ion battery, the as-prepared dual carbon-modified Na2MnPO4F composite exhibits a super discharge capacity of 122 mAh g−1 at 0.05 C and high rate-performance (42 mAh g−1 at 2 C) as well as long cycle performance (77% capacity retention after 200 cycles at 0.1 C). Meanwhile, it presents two obvious potential platforms of about 3.7 V and 3.5 V during the charge and discharge process, respectively, revealing its potential applications in high energy density batteries.  相似文献   

6.
《Ceramics International》2017,43(16):13710-13716
Development of novel electrode materials with high energy and power densities for lithium-ion batteries (LIBs) is the key to meet the demands of electric vehicles. Transition metal oxides that can react with large amounts of Li+ for electrochemical energy storage are considered promising anode materials for LIBs. In this work, NiCo2O4 nanosheets and nanocones on Ni foam have been synthesized via general hydrothermal growth and low-temperature annealing treatment. They exhibit high rate capacities and good cyclic performance as LIB anodes owing to their architecture design, which reduces ion and electron transport distance, expands the electrode–electrolyte contact, increases the structural stability, and buffers volume change during cycles. Notably, NiCo2O4 nanosheets deliver an initial capacity of 2239 mAh g−1 and a rate capacity of 964 mAh g−1 at current densities of 100 and 5000 mA g−1, respectively. The corresponding values of nanocones are 1912 and 714 mAh g−1. Hence, the as-synthesized NiCo2O4 nanosheets and nanocones, which are carbon-free and binder-free with higher energy densities and stronger connections between active materials and current collectors for better stability, are promising for use in advanced anodes for high-performance LIBs.  相似文献   

7.
《Ceramics International》2023,49(12):19737-19745
With the development of the energy industry, electrochemical energy storage technology is increasingly involved in developing innovations in the field. The materials of the electrode have a significant influence on the performance of energy storage devices. For this purpose, two-dimensional MXene with excellent electrical conductivity, mechanical strength, and a variety of possible surface-active terminations are attracting much attention. In the present work, S-decorated d-Mo2CTx (d-Mo2CTx--S) is designed. The first-principles calculations reveal that it may possess good energy storage characteristics. Due to the decoration with S, unique morphology and structure are obtained, conferring stability, optimized Li+ storage, improved charge transport, and lithium-ion adsorption capabilities. Compared with d-Mo2CTx, d-Mo2CTx--S exhibits higher discharge capacity (623 mAh g−1 at 1 A g−1) as lithium-ion electrode material and higher specific capacitance (561 F g−1 at 1 A g−1). As a supercapacitor, the material also shows excellent cyclic stability (20,000 charge-discharge cycles). This work may inspire the exploration of other MXene and new surface functionalization methods to improve the performance of MXene as electrode materials for new energy devices.  相似文献   

8.
《Chemical engineering science》1986,41(12):3141-3153
Kinetic results of the preceeding paper are used to formulate the most probable reaction mechanisms for the peroxide-induced and aerobic coupling of aqueous thiols. Parameters in the proposed mechanisms are evaluated for n-propylthiol using the results of independent measurements. A remarkably good agreement is achieved between the model and experimental results.The peroxide reaction, which is not affected by either copper ion or radical scavengers, is shown to be a nucleophilic substitution (SN 2) reaction which proceeds by a two-step mechanism as follows: RS + H2O2
RSOH + OH rate-determining RS + RSOH → RSSR + OH In the reaction the thiolate anion acts as the nucleophile while hydrogen peroxide and the transient sulfenic acid, RSOH, function as electrophiles.The most plausible mechanism for the copper-catalyzed, aerobic coupling reaction is as follows: Cu+ (RSSR)2+ + RS
(RSSR)Cu+ (RS) + RSSR (RSSR)Cu+ (RS) + RS
(RSSR)Cu+ (RS)2 (RSSR)Cu+ (RS)2 + O2
Cu+(RSSR)2+ + HO2 rate-determining RS + H2O2
RSOH + OH rate-determining RS + RSOH → RSSR + OH For the n-propylthiol substrate, the pertinent parameters in the mechanism are 1n (K1) = −11,000 K/T + 33.6, where K1 is dimensionless, 1n (K2) = 4270 K/T −10.5, where K2 is in 1/mol, 1n (k2) = 30.0 − 5260 K/T, and 1n (k2) = 26.8 − 6190 K/T, where k1 and k2 are in 1/(mol min).  相似文献   

9.
《Ceramics International》2020,46(17):26705-26714
Oxide + salt composites can be used in CO2 and NOx separation membranes, where high oxide-ion conductivity is crucial to improve performance. Pursuing this goal, the stability of three different bismuth oxide-based electrolytes (Cu + V, Y and Yb-doped) against molten alkali carbonates (Li, Na, K) or nitrates (Na, K) was tested firing them in the 450–550 °C temperature range, and with endurance tests up to 100 h. A well-known ceria-based composite was used as reference (CGO - Ce0.9Gd0.1O1.95). Oxides and composites were studied by X-ray diffraction, scanning electron microscopy and impedance spectroscopy (in air, 140–650 °C temperature range). Bi2Cu0.10V0.90O5.35 easily reacts with molten salts. Bi0.75Y0.25O1.5 and Bi0.75Yb0.25O1.5 have higher stability against molten carbonates and complete stability against molten nitrates. The Y-doped oxide stability against the molten carbonates was enhanced changing the molten salt composition (Y2O3 additions) and using lower firing temperatures. Above all, composites based on Y or Yb-doped Bi2O3 with molten alkali nitrates showed impressive 6× or 3× higher electrical conductivity at 290 °C, in air (4.88 × 10−2 and 2.41 × 10−2 S cm−1, respectively) than CGO-based composites (7.72 × 10−3 S cm−1), qualifying as promising materials for NOx separation membranes.  相似文献   

10.
L ‐Cysteine increased gold‐cyanide biosorption by protonated Bacillus subtilis, Penicillium chrysogenum and Sargassum fluitans biomass. At pH 2, the maximum Au uptakes were 20.5 µmol g−1, 14.2 µmol g−1 and 4.7 µmol g−1 of Au, respectively, approximately 148–250% of the biosorption performance in the absence of cysteine. Au biosorption mainly involved anionic AuCN2 species adsorbed by ionizable functional groups on cysteine‐loaded biomass carrying a positive charge when protonated [(biomass–cysteine–H+)–(AuCN2)]. Deposited gold could be eluted from Au‐loaded biomass at pH 3–5. The elution efficiencies were higher than 92% at pH 5.0 with the Solid‐to‐Liquid ratio, S/L, = 4. Increasing solution ionic strength (NaNO)3 decreased Au uptake. FTIR analyses indicated that the main functional groups involved in gold biosorption in the presence of L ‐cysteine are probably N‐, S‐ and O‐containing groups. The present results confirm that certain waste microbial biomaterials are capable of effectively removing and concentrating gold from solutions containing residual cyanide if applied under appropriate conditions. © 2000 Society of Chemical Industry  相似文献   

11.
《Ceramics International》2023,49(10):15451-15458
Layered manganese oxide represents one most potential cathode for sodium-ion batteries thanks to high theoretical specific capacity, low cost and environmental friendliness. Nevertheless, its surface structure degrades owing to the hydration reaction when being stored in the humid air. Herein, Na0.67Mn0.92Cu0.04Fe0.04O2 (NMCFO) cathode material is functionalized by tetradecylphosphonic acid (TPA) on the surface to enhance the air stability. It is demonstrated that the TPA protection layer could improve the surface hydrophobicity, and further inhibit the hydration reaction to produce residual alkali, effectively maintaining modified material’s crystal structure and electrochemical performance. After 28 days of placement in the humid air, the modified material delivers a specific capacity of 94.0 mAh g−1 at 5C, and exhibits a capacity retention of 92.22% after 100 cycles at 1C. In summary, we provide an effective pathway to protect layered manganese oxide and other moisture-sensitive materials without sacrificing cell performance.  相似文献   

12.
Three kinds of novel carboxyl modification tubular carbon nanofibers (CMTCFs) and MnO2 composites materials (CMTCFs/MnO2) are prepared by combining hyper-crosslinking, liquid phase oxidation and hydrothermal technology. The complex morphology and crystal phase of MnO2 in CMTCFs/MnO2 are effectively regulated by adjusting the hydrothermal reaction time. The δ-MnO2 nanosheet-wrapped CMTCFs (CMTCFs@MNS) are used as anode and compared with the other two CMTCFs/MnO2. Electrochemical analysis shows that CMTCFs@MNS electrode exhibits a large reversible capacity of 1497.1 mAh g−1 after 300 cycles at 1000 mA g−1 and a long cycling reversible capacity of 400.8 mAh g−1 can be maintained after 1000 cycles at 10 000 mA g−1. CMTCFs@MNS manifests an average reversible capacity of 256.32 mAh g−1 at 10 000 mA g−1 after twelve changes in current density. In addition, the structural superiority of CMTCFs@MNS electrode is clarified by characterizing the microscopic morphology and crystal phase of the electrode after electrochemical performance test.  相似文献   

13.
《Ceramics International》2019,45(15):18462-18470
Herein, porous NiMoO4@C nanowire is purposefully synthesized using oleic acid as carbon source, and further evaluated as high performance anode material for Li-ion batteries (LIBs). Compared with the pure NiMoO4, porous NiMoO4@C nanowire exhibits high reversible charge/discharge specific capacity, excellent cycle stability and preeminent rate capability. A stable reversible lithium storage capacity of 975 mAh g−1 can still be maintained after 100 cycles at 200 mA g−1. When the current density decreases back from 3000 mA g−1 to 100 mA g−1, a high discharge specific capacity of 884 mAh g−1 is recovered. The porous structure and carbon layers can enhance the electronic transmission and structural stability, shorten the path lengths for ion and electron transport, and provide a mechanical buffer space to accommodate the volume expansion/contraction during the repeated Li+ insertion/extraction processes. All the results highlight that the porous NiMoO4@C nanowire composite would be a promising candidate for high performance anode material of LIBs owing to its excellent electrochemical properties.  相似文献   

14.
《Ceramics International》2017,43(3):3218-3223
In this work, the nanosized porous MnCo2O4 microspheres were synthesized by a hydrothermal method and their electrochemical behaviors were investigated based on a carbon supported composite air electrode for rechargeable sodium-air batteries. Under dry air test condition, the MnCo2O4/C air electrode demonstrated a stable working voltage of around 2.1 V vs. Na+/Na and a high initial discharge capacity of 7709.4 mA h g−1, based on the active material mass, at a current density of 0.1 mA cm−2. By a limit on the depth of discharge, the cell exhibited a specific capacity of 1000 mA h g−1 with a high cycling stability up to 130 cycles. The considerable electrocatalytic activity suggests that the as-proposed MnCo2O4 is a highly efficient catalyst as air electrode for rechargeable sodium-air batteries.  相似文献   

15.
Designing defect-rich MoS2/C architectures with three-dimensional (3D) porous frame effectively improve the electrochemical performance of lithium-ion batteries (LIBs) owing to the improved conductivity and decreased diffusion distance of Li+ ions for lithium storage. Herein, we report a reliable morphology engineering method combining with tunable defects to synthesize defect-rich MoS2 nanosheets with a few layers entrapped carbon sheath, forming a 3D porous conductive network architecture. The defect-rich MoS2 nanosheets with expanded interlayers can provide a shortened ion diffusion path, and realize the 3D Li+ diffusion with faster kinetics. A 3D conductive interconnected carbon network is able to improve interparticle conductivity, concurrently maintaining the structural integrity. Benefiting from these intriguing features, the as-prepared MoS2/C architectures exhibit excellent electrochemical performance: a high reversible capacity of 1163 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles and a high rate capability of 800 mAh g−1 at 5 A g−1. Defect content in MoS2/C architectures can be obtained by changing H2 concentration. Compared with the counterparts with few defects, the defect-rich MoS2/C architectures show improved electrochemical stability with a superior cycle life, illustrating a highly reversible capacity of 751 mAh g−1 at 0.5 A g−1 after 500 cycles.  相似文献   

16.
Factors affecting silver biosorption by Saccharomyces cerevisiae biomass, obtained as a waste product from industry, were examined. Maximum removal of silver from solution was achieved within 5 min. Increasing the concentration of biomass in experimental flasks from 1 to 8 mg cm−3 decreased both silver accumulation, from 224·7 to 89·5 μmol Ag g−1 dry wt, and associated H+ ion release, from 109·4 to 31·7 μmol H+ g−1 dry wt. The presence of 1·0 mol dm−3 cadmium or methionine decreased silver biosorption by 40% and 93% respectively. Boiling in 100 mmol dm−3 NaOH or 10 mmol dm−3 sodium dodecyl sulphate decreased silver biosorption by 54% and 25% respectively. A temperature increase from 4°C to 55°C decreased silver biosorption by 9%. The metabolic state of the yeast had no effect on silver biosorption. Decreasing the pH of the silver solution caused a reduction in metal removal by the biomass.  相似文献   

17.
Currently, coupling noble metal species with rare‐earth cations (REI) in amorphous materials has attracted persistent attention, owing to the significant rise in the emission intensity and nonlinear optical response, which allow various potential applications in photoelectric fields. However, the primary investigations are focused on Au‐ and Ag‐doped systems, and there are few systematic reports concerning the interaction between REI and the different oxidation states of copper so far. Herein, we demonstrated the evolution of copper oxidation valences from Cu2+ to Cu+, and then to Cu0 (Cu NPs), and the corresponding effects on Tb3+ emissions in borate glasses were systematically investigated by modifying glass structure and Sn2+/Si codoping. With increasing the ratio of B2O3 to Li2O, enhancement of reduction efficiency of Cu2+ to Cu+ was observed. Impressively, the ns2‐type Sn2+ emission centers not only generate efficient sensitizers for Tb3+ but also lead to efficient reduction in Cu2+ to Cu+. Based on absorption/transmittance, photoluminescence excitation/emission, and time‐resolved decay spectra, the interplay mechanisms between Tb3+ and the different valences of copper were discussed in detail.  相似文献   

18.
Thin Cu2Sb films have been prepared by heat-treating Sb films, electrodeposited on Cu substrates. The influence of the electrodeposition conditions and the heat-treatment period on composition and morphology of the films were investigated (SEM and XRD) and the obtained films were tested as anode materials for Li-ion batteries. The Cu2Sb material showed a stable capacity of 290 mAh g−1 (close to the theoretical capacity of 323 mAh g−1) during more than 60 cycles. The presence of 9-11% (w/w) Sb2O3 in the electrodeposited films resulted in smaller particles but also slowed down formation of Cu2Sb during the heat-treatment step. The presence of Sb2O3 was found to decrease the cycling stability although structural reversibility of Cu2Sb was obtained both with and without Sb2O3. Longer heat-treatments of pure Sb films resulted in the formation of Cu9Sb2 which was shown to be reduced at a lower potential than Cu2Sb. The Cu9Sb2 was converted to Cu2Sb during repeated cycling and the capacity of the latter Cu2Sb material was found to be 230 mAh g−1. While reduction of the materials was complicated by simultaneous formation of an SEI layer, three plateaus could be identified during the oxidation of Li3Sb, indicating the presence of three separate one-electron oxidation reactions.  相似文献   

19.
《Ceramics International》2023,49(19):31891-31897
Layered materials exhibit competitively low thermal conductivity along the out-of-plane direction. The solution process is a promising method for preparing stacked structures. However, the thermal stability of the layered materials is poor after processing in solution, thus hindering their applications at high temperatures. One of the solutions to improve the thermal stability of layered structures is to expand the interlayer distance by inserting large-size metal ions. In this work, we studied the thermal properties of Cs+ intercalated layered niobate obtained by the ion-exchanged process. The layered structure of the Cs+ intercalated layered niobate survives after thermal treatment even at 1200 °C. The room temperature thermal conductivity of as prepared stacked Cs–HCa2Nb3O10 is as low as 0.11 W m−1 k−1. Upon thermal annealing, the thermal conductivity increases. After annealing at 1200 °C, the value is 0.90 W m−1 k−1. The finding suggests Cs+ intercalated layered niobate is a promising material for high-temperature insulation applications.  相似文献   

20.
《Ceramics International》2020,46(17):27010-27020
In this work, hierarchical flower-like Li1.2Ni0.13Co0.13Mn0.54O2 (LNCM) with exposed {010} planes assembled and double-sphere Li1.2Ni0.13Co0.13Mn0.54O2 without {010} planes as a comparison were successfully synthesized via a simple solvothermal method. The diffusion of Li+ could be enhanced in the flower-like LNCM with exposed {010} active planes, and the cathode exhibits a superior electrochemical performance especially in long-term cycling stability even at high current densities. The initial discharge capacity of this sample is 274 mA h g−1 at 0.1C (25 mA g−1), with corresponding initial coulombic efficiencies of 77%. Especially, the capacity retention reaches up to 98% at 1250 mA g−1 current density after 100 cycles. By comparing with other LNCM materials reported recently, our optimal cathode has a pretty outstanding electrochemical performance, which is promising for the next generation lithium ion batteries.  相似文献   

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