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1.
J Colloid Interface Sci ; 675: 870-882, 2024 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-39002237

RESUMEN

Microstructural engineering is regarded as a promising option for fabricating high-performance carbon anodes. Hence, a facile solvothermal-assisted low-temperature calcination strategy was employed to modulate the microstructure of semicoke-derived carbon anodes. Owing to the effective pseudo-graphite phase modulation, the modified carbon anode exhibited a significant increase in capacity, cycling stability and ion kinetics in both lithium-ion batteries and sodium-ion batteries. Kinetic analysis and in-situ X-ray diffraction confirmed the "adsorption and intercalation" energy storage mechanism of the obtained carbon electrodes. In addition, by investigating the energy storage mechanism, we found that increasing the pseudo-graphite phase proportion played different roles in lithium and sodium ions storage. For lithium-ion storage, the pseudo-graphitic phase preferentially promotes lithium-ion transport kinetics. Conversely, during sodium-ion storage, this particular structure markedly augments the embedding capacity of sodium. Theoretical calculations demonstrate that different patterns of variation in the activation energy with the carbon layer spacing of lithium/sodium intercalation compounds lead to differences in performance enhancement. This study not only offers a low-cost approach for preparing carbon anodes enriched with a pseudo-graphitic phase, but also provides new insight into the discrepancy between lithium ion and sodium ion storage.

2.
Front Microbiol ; 15: 1390030, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38887709

RESUMEN

Introduction: Aspergillus cristatus is a homothallic fungus that is used in the natural fermentation process of Chinese Fuzhuan tea and has been linked to the production of bioactive components. However, not much is known about the variations present in the fungus. To understand the variation of the dominant microorganism, A. cristatus, within dark tea, the present study investigated the genetic and morphological diversity of 70 A. cristatus collected across six provinces of China. Methods: Expressed sequence tags-simple sequence repeats (EST-SSR) loci for A. cristatus were identified and corresponding primers were developed. Subsequently, 15 specimens were selected for PCR amplification. Results: The phylogenetic tree obtained revealed four distinct clusters with a genetic similarity coefficient of 0.983, corresponding to previously identified morphological groups. Five strains (A1, A11, B1, D1, and JH1805) with considerable differences in EST-SSR results were selected for further physiological variation investigation. Microstructural examinations revealed no apparent differentiation among the representative strains. However, colony morphology under a range of culture media varied substantially between strains, as did the extracellular enzymatic activity (cellulase, pectinase, protease, and polyphenol oxidase); the data indicate that there are differences in physiological metabolic capacity among A. cristatus strains. Discussion: Notably, JH1805, B1, and A11 exhibited higher enzymatic activity, indicating their potential application in the production of genetically improved strains. The findings provide valuable insights into species identification, genetic diversity determination, and marker-assisted breeding strategies for A. cristatus.

3.
Adv Mater ; 36(26): e2401249, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38529803

RESUMEN

Increasing closed pore volume in hard carbon is considered to be the most effective way to enhance the electrochemical performance in sodium-ion batteries. However, there is a lack of systematic insights into the formation mechanisms of closed pores at molecular level. In this study, a regulation strategy of closed pores via adjustment of the content of free radicals is reported. Sufficient free radicals are exposed by part delignification of bamboo, which is related to the formation of well-developed carbon layers and rich closed pores. In addition, excessive free radicals from nearly total delignification lead to more reactive sites during pyrolysis, which competes for limited precursor debris to form smaller microcrystals and therefore compact the material. The optimal sample delivers a large closed pore volume of 0.203 cm3 g-1, which leads to a high reversible capacity of 350 mAh g-1 at 20 mA g-1 and enhanced Na+ transfer kinetics. This work provides insights into the formation mechanisms of closed pores at molecular level, enabling rational design of hard carbon pore structures.

4.
J Colloid Interface Sci ; 661: 436-449, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38306751

RESUMEN

Hyper cross-linked polymers (HCPs), as a key precursor of hard carbon (HC) anode materials, stand out because of their capacity for molecular-scale structural design and comparatively straightforward preparation techniques, which are not seen in other porous materials synthesized procedure. A novel synthesis method of HCPs is developed in this paper, which is through the incorporation of functional macromolecules, the structural control and heteroatom doping of the product has been achieved, thus augmenting its electrochemical performance in batteries. In this work, carbonized tetraphenylporphyrin zinc (TPP-Zn) doped HCP-based hard carbon (CTHCP) with stable structure was prepared by Friedel-Crafts reaction and carbonization by using naphthalene and trace TPP-Zn as monomers, dimethoxybenzene (DMB) as crosslinking agent and FeCl3 as catalyst. The introduction of TPP-Zn, a functional macromolecule with unique two-dimensional structure, realized the pore structure regulation and N doping of the raw carbonized HCP-based hard carbon (CHCP). The results showed that CTHCP had higher mesoporous volume, N content and wider layer spacing than CHCP. In addition, CTHCP anode exhibited excellent Li+/Na+ storage performance, initial reversible capacity, rate performance and long cycle life. More amount of N-containing (N-5) active sites and mesoporous content in CTHCP anode was the main reason for the improvement of Na+ storage effect. While the increased interlayer spacing had a greater effect on the lithium storage capacity. This study uncovered the design rules of HC anode materials suitable for Li+/Na+ batteries and provided a new idea for the preparation of high-performance HC anode materials.

5.
Phys Rev Lett ; 132(3): 035102, 2024 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-38307060

RESUMEN

We report the first experimental observation on the reduction of backward scatterings by an instantaneous broadband laser with 0.6% bandwidth in conditions of interest for inertial confinement fusion at the low-coherence Kunwu laser facility. The backscatter of stimulated Brillouin scattering (SBS) was robustly reduced by half at intensities of 1-5×10^{14} W/cm^{2} with the 0.53-µm broadband laser in comparison with the monochromatic laser. As SBS dominates energy loss of laser-plasma interactions, the reduction of that demonstrates the enhancement of laser-target coupling by the use of broadband laser. The mitigation of filamentation leads to the reduction of stimulated Raman backscattering at low intensities. In addition, the three-halves harmonic emission was reduced with the broadband laser as well.

6.
ACS Appl Mater Interfaces ; 15(47): 54386-54396, 2023 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-37972078

RESUMEN

Although supercapacitors with acetonitrile-based electrolytes (AN-based SCs) have realized high-voltage (3.0 V) applications by manufacturers, gas generation at high voltages is a critical issue. Also, the exact origins and evolution mechanisms of gas generation during SC aging at 3.0 V still lack a whole landscape. In this work, floating tests under realistic working conditions are conducted by 22450-type cylindrical cells with an AN-based commercial electrolyte. Comprehensive insights into the origins and evolution mechanisms of gas species at 2.7 and 3.0 V are acquired, which involves multiple side reactions related to the electrode, current collector, and electrolyte. Both experimental evidence and density functional theory calculations demonstrate that the primary reasons for gas generation are residual water and oxygen-containing functional groups, especially hydroxyl and carboxyl. More importantly, additional types of gas (such as CO2, NH3, and alkenes) can only be detected at a higher voltage of 3.0 V rather than 2.7 V after failure, suggesting that these gas species can be regarded as the failure signatures at 3.0 V. This breakthrough analysis will provide fundamental guidance for failure evaluation and designing AN-based SCs with extended lifetime at 3.0 V.

7.
Nat Commun ; 14(1): 5782, 2023 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-37723172

RESUMEN

In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43-50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6-4.0 kJ at an intensity of 1.8 × 1015 W/cm2, in the hemispherical and planar targets the boosted HD pressures reach 3.8-4.0 and 3.5-3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.

8.
RSC Adv ; 13(9): 6075-6086, 2023 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-36814883

RESUMEN

The state-of-the-art graphite foams (GFs) are afflicted by large bulk density and low thermal conductivity, restricting their practical application. To alleviate the above problem, herein, an issue-oriented scheme, i.e., an in situ titanium (Ti) assisted catalytic graphitization strategy was proposed by using AR mesophase pitch (ARMP) as a precursor. In a typical preparation process, the mixture of Ti and ARMP underwent a pressurized foam, carbonization, and graphitization procedure successively to obtain GFs. The results showed that the Ti content played an important role in the development of the graphitic microcrystal structure due to the catalytic graphitization of Ti. According to the XRD analysis and molecular dynamics (MD) simulation, we confirmed that Ti promoted graphitization mainly by the generation of TiC during the high-temperature graphitization. The GFs obtained with 11 wt% Ti exhibited the most perfect graphitic crystal structure, with the highest graphitization degree. Thanks to the improved graphitization degree, the thermal conductivity of GFs increased with the added amount of Ti increasing from 0 to 11 wt%. The highest thermal conductivity of 60.8 W m-1 K-1 and the low bulk density of 0.36 g cm-3 could be achieved when the addition amount of Ti was 11 wt%. Meanwhile, apart from the optimization of thermal conductivity and bulk density, the compressive strength was also enhanced as the amount of Ti increased from 0 to 15 wt%. Our work provided a facile and scalable approach to preparing GFs with low density and high thermal conductivity.

9.
Open Life Sci ; 18(1): 20220573, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36820207

RESUMEN

The composition and diversity of microbial communities are of considerable significance to the quality development of Camellia sinensis (Fuzhuan tea). In this study, we examined differences in the bacterial community structures of loose, lightly-pressed, hand-made, and machine-pressed Fuzhuan teas and raw dark tea. We observed notable differences in the bacterial communities of the five groups, where there were only 51 consensus sequences. ASV/OTU Venn diagram, Chao1, Ace, Simpson indices, and dilution curve analyses consistently revealed that machine-pressed tea exhibited the highest bacterial diversity. Taxonomically, Actinobacteria, Firmicutes, Proteobacteria, and Cyanobacteria were the dominant bacterial phyla in each group, whereas Corynebacterium, Methylobacterium, and Bifidobacterium were the dominant genera. Our findings revealed significant differences in the bacterial community structures of different Fuzhuan tea products derived from the same raw material, with bacterial diversity rising with increased product compaction.

10.
Sci Total Environ ; 869: 161791, 2023 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-36707003

RESUMEN

Although the repaid development of China's apple industry heavily depends on excessive fertilizer-water-pesticide (FWP) inputs, little information is available that systematically evaluates environmental impacts, mitigation potential, and economical benefits of apple production systems in China. In this study, life cycle assessment (LCA) was conducted to elucidate environmental risks and mitigation potentials of rain-fed and irrigated apple production systems on China's Loess Plateau based on survey data from 847 farmers, and economic benefits were analyzed simultaneously. Results showed that irrigated orchards caused more severe environmental risks associated with energy depletion (ED), global warming potential (GWP) and acidification potential (AP) than those in rain-fed orchards, whereas an opposite was true for eutrophication potential (EP), human toxicity potential (HTP), aquatic toxicity potential (ATP) and soil toxicity potential (STP). ED and GWP occurred primarily in the agricultural material stage, while AP, EP, HTP, ATP, and STP occurred mostly in the orchard management stage. Optimized FWP management can markedly mitigate environmental impacts in both irrigated and rain-fed orchard systems. Synthetic fertilizer, because of production and field-associated emissions, was the greatest contributor to environmental impacts of an apple production system. An environmental pollution index (EPI) that integrated environmental categories was highest in conventional irrigated orchards (0.946), followed by conventional rainfed orchards (0.857), and optimized irrigated orchards (0.459), and the lowest EPI was in optimized rainfed orchards (0.389). Economic analysis revealed that the benefits of rainfed orchards were higher than those of irrigated orchards because of higher apple prices and lower labor costs. Optimized FWP management sharply decreased input costs, thereby substantially increasing net income in irrigated and rain-fed apple orchards. Overall, severe environmental risk and large mitigation potential co-exist in rain-fed and irrigated apple orchards on China's Loess Plateau. Integrated soil-crop-market management potentially exhibited considerable environmental and economic advantages, thereby efficiently developing high-quality apple production.


Asunto(s)
Malus , Plaguicidas , Humanos , Fertilizantes , Ambiente , Suelo , Agricultura/métodos , Lluvia , China , Agua , Adenosina Trifosfato
11.
Sci Total Environ ; 854: 158790, 2023 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-36116642

RESUMEN

Evaluating soil aggregation and microbial activities within soil aggregates contributes to understanding carbon (C) and nitrogen (N) cycling. Here we examined soil aggregate distribution, C and N pools, and extracellular enzymatic activities (EEAs) in soil aggregates after 16-year mulching (CT, no mulch; RF, plastic-mulched ridges and straw-mulched furrows; SM, straw mulch) and N fertilization (0, 120, and 240 kg ha-1). RF and SM significantly increased macroaggregate formation and aggregate stability (MWD, mean weight diameter) but N rate did not. Mulching had similar effects on aggregate-associated SOC (soil organic C) and TN (total N), with the order SM > RF > CT in macroaggregates and macroaggregate-occluded microaggregates. N input significantly increased TN in most cases, whereas its effect on SOC was only significant in SM. Notably, the majority of SOC and TN was isolated in the macroaggregate-occluded silt and clay fractions. SOC, TN, microbial biomass C (MBC), and microbial biomass N (MBN) decreased as aggregate-size decreased, whereas C- and N-acquiring enzymes varied greatly across aggregate fractions. Mulching had greater effects than N-fertilization on soil C and N pools and EEAs, whilst SM performed more beneficial effects than RF on SOC, TN, MBC, MBN, and EEAs. MBC rather than SOC was associated with MWD in bulk soil, while significant relations between MWD and SOC were observed in macroaggregates and macroaggregate-occluded microaggregates. Partial least squares path modeling illustrated that soil aggregation was the most important factor affecting SOC and TN, followed by mulching and N addition. Regression analysis further revealed that α-glucosidase and leucine aminopeptidase were major variables mediating SOC and TN dynamics at the aggregate scale. This study highlights the importance of macroaggregate-occluded microaggregate fraction sensitively evaluating soil C and N dynamics, and straw mulch can effectively increase soil aggregation and stabilization of C and N in semiarid areas with infertile soils.


Asunto(s)
Carbono , Suelo , Carbono/análisis , Agricultura , Nitrógeno/análisis , Arcilla , China
12.
Nanomaterials (Basel) ; 12(22)2022 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-36432353

RESUMEN

Fast charging capability is highly desired for new generation lithium-ion batteries used in consumer-grade electronic devices and electric vehicles. However, currently used anodes suffer from sluggish ion kinetics due to limited interlayer distance. Herein, the coal-based semicoke was chosen as precursor to prepare cost-effective carbon anodes with high-rate performance through a facile pyrolytic strategy. The evolution of microstructure and its effect on electrochemical performance are entirely studied. The results show that large number of short-ordered defective structures are generated due to the occurrence of turbostatic-like structures when pyrolyzed at 900 °C, which are propitious to large interlayer distance and developed porous structure. High accessible surface area and large interlayer spacing with short-ordered defective domains endow the sample treated at 900 °C under argon (A900) with accelerated ion dynamics and enhanced ion adsorption dominated surface-induced capacitive processes. As a result, A900 delivers high capacity (331.1 mAh g-1 at 0.1 A g-1) and long life expectancy (94.8% after 1000 cycles at 1 A g-1) as well as good rate capability (153.2 mAh g-1 at 5 A g-1). This work opens a scalable avenue to fabricating cost-effective, high-rate, and long cycling life carbon anodes.

13.
ACS Appl Mater Interfaces ; 14(42): 47674-47684, 2022 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-36223510

RESUMEN

The development of potassium-ion batteries (PIBs) has been impeded by the lack of an appropriate carbon anode material that could accommodate K+ with a large ionic radius. Hard carbon with low cost and larger interlayer spacing is a promising anode material for PIBs. However, the impact of oxygen-containing functional groups in hard carbon (HC) is less reported. Herein, a hypercrosslinked polymer (HCLP) is prepared and used for the synthesis of microporous hard carbons with superior structural stability and abundant oxygen-containing functional groups and defects, in which the crosslinking agent provided copious oxygen atoms. It is found that a large number of C═O groups and micropores provide more storage sites for K+. The surface-controlled process is dominated by the reversible reaction of C═O + K+ + e- ↔ C-O-K, which directly increases the capacity contribution. The HCs obtained at 600 °C exhibit good cycling and rate performance with an initial specific capacity of about 254.3 mAh g-1 and the capacity retention of 83.2% after 200 cycles at 50 mA g-1. The capacity reached up to 121 mAh g-1 at 2 A g-1. A possible capacitive-adsorption mechanism is proposed by kinetic analysis. The redox reaction mechanism between C═O and K+ at the HC is clearly also revealed.

14.
J Colloid Interface Sci ; 605: 129-137, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34311307

RESUMEN

Lithium-sulfur (Li-S) batteries are greatly expected to be the favored alternatives in the next-generation energy-storage technologies due to their exceptional advantages. However, the shuttle effect and sluggish reaction kinetics of polysulfides largely hamper the practical success of Li-S batteries. Herein, a unique iron carbide (Fe3C) nanoparticles-embedded porous biomass-derived carbon (Fe3C-PBC) is reported as the excellent immobilizer and promoter for polysulfides regulation. Such a distinctive composite strongly couples the vast active sites of Fe3C nanoparticles and the conductive network of porous biomass-derived carbon. Therefore, Fe3C-PBC is endowed with outstanding adsorptivity and catalytic effect toward inhibiting the shuttle effect and facilitating the redox kinetics of polysulfides, demonstrated by the detailed experimental demonstrations and theoretical calculation. With these synergistic effects, the Fe3C-PBC/S electrode embraces a superb capacity retention of 82.7% at 2C over 500 cycles and an excellent areal capacity of 4.81 mAh cm-2 under the high-sulfur loading of 5.2 mg cm-2. This work will inspire the design of advanced hosts based on biomass materials for polysulfides regulation in pursuing the superior Li-S batteries.


Asunto(s)
Litio , Nanopartículas , Biomasa , Carbono , Compuestos Inorgánicos de Carbono , Compuestos de Hierro , Porosidad , Sulfuros , Azufre
15.
Small ; 18(4): e2105275, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34841653

RESUMEN

Soft carbon (SC) has become a promising anode for potassium ion batteries (PIBs) benefiting from its structural flexibility. However, the evolution of potassium storage behavior with the microstructure (the average size of the crystallites La and the average interlayer spacing a3 ) is still unclear, which hinders the understanding of the potassium storage mechanism. Herein, a series of soft carbon with different microstructures is prepared through pyrolysis of petroleum pitch. Based on the analysis of the relationship between electrochemical behavior and microstructure, an adsorption-insertion mechanism is proposed: the capacity in the voltage range of 0.45-1.1 V is originated from the adsorption of potassium ions on edge-defect sites whereas the capacity below 0.45 V is attributed to the insertion of potassium ions into interlayers. When La equals to 10.56 Å, SCs exhibit an adsorption-controlled mechanism. However, as La increases to 120.98 Å, the insertion process is dominant. With La increasing from 21.9 to 93.02 Å, SCs have two mixed behaviors. The initial insertion coefficients do not change until a3 decreases to 3.46 Å. These findings highlight the relation of potassium storage behavior with different microstructures and the adsorption-insertion mechanism can provide insights into the design of SC anodes for PIBs.


Asunto(s)
Carbono , Potasio , Adsorción , Suministros de Energía Eléctrica , Iones
16.
J Colloid Interface Sci ; 610: 418-426, 2022 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-34929512

RESUMEN

Lithium-sulfur (Li-S) batteries with the prominent advantages are greatly expected to be the attractive alternatives in the next-generation energy-storage systems. However, the practical success of Li-S batteries suffers from the shuttle effect and depressed redox kinetics of polysulfides. Herein, for the first time, InOOH nanoparticles are employed as a potent catalytic additive in sulfur electrode to overcome these issues. As demonstrated by the theoretical and experimental results, the strong interactions between the InOOH nanoparticles and sulfur species enable the effective adsorption of polysulfides. More significantly, InOOH nanoparticles not only effectively expedite the reduction of sulfur during the discharge process, but also dramatically accelerate the oxidation of Li2S during the charge process, presenting the marvelous bidirectional catalytic effects. Benefited from these distinctive superiorities, the cells with InOOH nanoparticles harvest an excellent capacity retention of 69.5% over 500 cycles at 2C and a commendable discharge capacity of 891 mAh g-1 under a high-sulfur loading of 5.0 mg cm-2. The detailed investigations in this work provide a novel insight to ameliorate the Li-S electrochemistry by the bidirectional catalyst for high-performance Li-S batteries.

17.
J Colloid Interface Sci ; 602: 504-512, 2021 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-34144304

RESUMEN

Developing effective and robust novel electrocatalysts for direct alcohol fuel cells has been gaining much attention. However, the widely used Pt catalyst suffers from limitations including the sluggish kinetics, severe CO poisoning, and catalyst lost caused by aggregation and Ostwald ripening during alcohol oxidation reaction. Herein, dendritic intermetallic PtSnBi nanoalloys were synthesized via a facile hydrothermal approach with high electrocatalytic performance and enhanced CO resistance for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) owing to the synergism of the chosen three elements and unique three-dimensional morphology. Specifically, the PtSnBi nanoalloys display 4.6 and 6.7 times higher of mass activity (7.02 A mg-1Pt) and specific activity (16.65 mA cm-2) toward MOR than those of commercial Pt/C, respectively. The mass activity of PtSnBi nanoalloys still retains 75.7% of the initial value after 800 cycles of stability test, superior to Pt/C (38.0%). The dual-functional effect of Sn, optimized electronic structure by the ligand effect, and unique atomic arrangement are responsible for the enhanced MOR activity and stability of PtSnBi nanoalloys. Furthermore, the PtSnBi nanoalloys with highlighted anti-CO poisoning capacity also improve the electrocatalytic performance toward EOR, indicating their great promise as broad energy electrocatalysts.

18.
Chem Sci ; 12(17): 6048-6058, 2021 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-33996000

RESUMEN

Electrocatalytic C-N coupling reaction by co-activation of both N2 and CO2 molecules under ambient conditions to synthesize valuable urea opens a new avenue for sustainable development, while the actual catalytic activity is limited by poor adsorption and coupling capability of gas molecules on the catalyst surface. Herein, theoretical calculation predicts that the well-developed built-in electric field in perovskite hetero-structured BiFeO3/BiVO4 hybrids can accelerate the local charge redistribution and thus promote the targeted adsorption and activation of inert N2 and CO2 molecules on the generated local electrophilic and nucleophilic regions. Thus, a BiFeO3/BiVO4 heterojunction is designed and synthesized, which delivers a urea yield rate of 4.94 mmol h-1 g-1 with a faradaic efficiency of 17.18% at -0.4 V vs. RHE in 0.1 M KHCO3, outperforming the highest values reported as far. The comprehensive analysis further confirms that the local charge redistribution in the heterojunction effectively suppresses CO poisoning and the formation of the endothermic *NNH intermediate, which thus guarantees the exothermic coupling of *N[double bond, length as m-dash]N* intermediates with the generated CO via C-N coupling reactions to form the urea precursor *NCON* intermediate. This work opens a new avenue for effective electrocatalytic C-N coupling under ambient conditions.

19.
Opt Lett ; 46(6): 1285-1288, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33720168

RESUMEN

Isolated attosecond pulses are useful to perform pump-probe experiments at a high temporal resolution, and provide a new tool for ultrafast metrology. However, it is still a challenging task to generate such pulses of high intensity, even for a few-cycle laser. Through particle-in-cell simulations, we show that it is possible to directly generate a giant isolated attosecond pulse in the transmission direction from relativistic laser-driven plasmas. Compared to attosecond pulse generation in the reflection direction, no further spectral filtering is needed. The underlying radiation mechanism is coherent synchrotron emission, and the transmitted isolated attosecond pulse can reach relativistic intensity. This provides a promising alternative to generate intense isolated attosecond pulses for ultrafast studies.

20.
Angew Chem Int Ed Engl ; 60(19): 10910-10918, 2021 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-33634560

RESUMEN

Electrocatalytic C-N bond coupling to convert CO2 and N2 molecules into urea under ambient conditions is a promising alternative to harsh industrial processes. However, the adsorption and activation of inert gas molecules and then the driving of the C-N coupling reaction is energetically challenging. Herein, novel Mott-Schottky Bi-BiVO4 heterostructures are described that realize a remarkable urea yield rate of 5.91 mmol h-1 g-1 and a Faradaic efficiency of 12.55 % at -0.4 V vs. RHE. Comprehensive analysis confirms the emerging space-charge region in the heterostructure interface not only facilitates the targeted adsorption and activation of CO2 and N2 molecules on the generated local nucleophilic and electrophilic regions, but also effectively suppresses CO poisoning and the formation of endothermic *NNH intermediates. This guarantees the desired exothermic coupling of *N=N* intermediates and generated CO to form the urea precursor, *NCON*.

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