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1.
ACS Nano ; 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32101395

RESUMO

The aprotic lithium-oxygen (Li-O2) battery has triggered tremendous efforts for advanced energy storage due to the high energy density. However, realizing toroid-like Li2O2 deposition in low-donor-number (DN) solvents is still the intractable obstruction. Herein, a heterostructured NiS2/ZnIn2S4 is elaborately developed and investigated as a promising catalyst to regulate the Li2O2 deposition in low-DN solvents. The as-developed NiS2/ZnIn2S4 promotes interfacial electron transfer, regulates the adsorption energy of the reaction intermediates, and accelerates O-O bond cleavage, which are convincingly evidenced experimentally and theoretically. As a result, the toroid-like Li2O2 product is achieved in a Li-O2 battery with low-DN solvents via the solvation-mediated pathway, which demonstrates superb cyclability over 490 cycles and a high output capacity of 3682 mA h g-1. The interface engineering of heterostructure catalysts offers more possibilities for the realization of toroid-like Li2O2 in low-DN solvents, holding great promise in achieving practical applications of Li-O2 batteries as well as enlightening the material design in catalytic systems.

2.
Nutrients ; 12(1)2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31936037

RESUMO

Hyperlipidemia is associated with metabolic disorders, but the detailed mechanisms and related interventions remain largely unclear. As a functional food in Asian diets, Herba houttuyniae has been reported to have beneficial effects on health. The present research was to investigate the protective effects of Herba houttuyniae aqueous extract (HAE) on hyperlipidemia-induced liver and heart impairments and its potential mechanisms. Male C57BL/6J mice were administered with 200 or 400 mg/kg/day HAE for 9 days, followed by intraperitoneal injection with 0.5 g/kg poloxamer 407 to induce acute hyperlipidemia. HAE treatment significantly attenuated excessive serum lipids and tissue damage markers, prevented hepatic lipid deposition, improved cardiac remodeling, and ameliorated hepatic and cardiac oxidative stress induced by hyperlipidemia. More importantly, NF-E2 related factor (Nrf2)-mediated antioxidant and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α)-mediated mitochondrial biogenesis pathways as well as mitochondrial complex activities were downregulated in the hyperlipidemic mouse livers and hearts, which may be attributable to the loss of adenosine monophosphate (AMP)-activated protein kinase (AMPK) activity: all of these changes were reversed by HAE supplementation. Our findings link the AMPK/PGC-1α/Nrf2 cascade to hyperlipidemia-induced liver and heart impairments and demonstrate the protective effect of HAE as an AMPK activator in the prevention of hyperlipidemia-related diseases.

3.
Nat Commun ; 10(1): 4973, 2019 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-31672990

RESUMO

The growing demand for lithium batteries with higher energy densities requires new electrode chemistries. Lithium metal is a promising candidate as the anode material due to its high theoretical specific capacity, negative electrochemical potential and favorable density. However, during cycling, low and uneven lithium ion concentration on the surface of anode usually results in uncontrolled dendrite growth, especially at high current densities. Here we tackle this issue by using lithiophilic montmorillonite as an additive in the ether-based electrolyte to regulate the lithium ion concentration on the anode surface and thus facilitate the uniform lithium deposition. The lithiophilic montmorillonite demonstrates a pumping feature that improves the self-concentrating kinetics of the lithium ion and thus accelerates the lithium ion transfer at the deposition/electrolyte interface. The signal intensity of TFSI- shows negligible changes via in situ Raman tracking of the ion flux at the electrochemical interface, indicating homogeneous ion distribution, which can lead to a stable and uniform lithium deposition on the anode surface. Our study indicates that the interfacial engineering induced by the lithiophilic montmorillonite could be a promising strategy to optimize the lithium deposition for next-generation lithium metal batteries.

4.
Free Radic Biol Med ; 135: 251-260, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30878647

RESUMO

Accumulating evidence has elucidated that hyperlipidemia is closely associated with an increasing prevalence of CVDs (cardiovascular diseases) because of endothelial dysfunction. In the present study, we investigated the effect and mechanism of PU (Punicalagin), a major ellagitannin in pomegranate, on endothelial dysfunction both in vivo and in vitro. In vivo, PU significantly ameliorated hyperlipidemia-induced accumulation of serum triglyceride and cholesterol as well as endothelial and mitochondrial dysfunction of thoracic aorta. Intriguingly, the FoxO1 (forkhead box O1) pathway was activated, which may account for prevention of vascular dysfunction and mitochondrial loss via upregulating mitochondrial biogenesis. In line, through in vitro cell cultures, our study demonstrated that PU not only increased the total FoxO1 protein, but also enhanced its nuclear translocation. In addition, silencing of FoxO1 remarkably abolished the ability of PU to augment the mitochondrial biogenesis, eNOS (endothelial NO synthase) expression, and oxidative stress, implying the irreplaceable role of FoxO1 in regulating endothelial function in the presence of PU. Conversely, suppression of excessive ROS (reactive oxygen species) secured the PA (palmitate)-induced decrease of FoxO1 expression, implying that there was a cross-talk between FoxO1 pathway and ROS. Concomitantly, the inflammatory response in current study was primarily mediated via p38 MAPK/NF-κB signaling pathway besides of FoxO1 pathway. Taken together, our findings suggest that PU ameliorates endothelial dysfunction by activating FoxO1 pathway, a pivotal regulating switch of mitochondrial biogenesis.

5.
Chemistry ; 25(10): 2604-2609, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30537126

RESUMO

Si/SiOC composites are promising high-capacity anode materials for lithium-ion batteries since the SiOC matrix can effectively buffer the volumetric change of Si during cycling. However, a structure of Si nanoparticles (NPs) enwrapped by a continuous SiOC phase typically shows poor cyclic stability and low charge/discharge rate due to structure failure of bulk SiOC shells derived from carbon-rich organosilicon. To address this issue, in this work, an Si/SiOC nanocomposite with volume-change-buffering microstructure, in which Si NPs are uniformly dispersed in a matrix of SiOC nanospheres, has been synthesized. Our results show that the space between Si and SiOC NPs can accommodate the large volume change of Si during cycling and facilitate infiltration of the electrolyte. The nanostructured SiOC skeleton serves as both a mechanically robust buffer to alleviate the intrinsic expansion of Si and an effective electron conductor. The Si/SiOC NP composite displays significantly increased capacity and cyclic stability compared with pure SiOC, and delivers reversible capacities of around 800 mA h-1 g-1 at a current density of 100 mA g-1 (approximately 100 % capacity retention after 100 cycles) and around 600 mA h-1 g-1 at 500 mA g-1 (capacity retention about 80 % after 500 cycles).

6.
Adv Mater ; : e1804084, 2018 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-30141197

RESUMO

Fast lithium ion transport with a high current density is critical for thick sulfur cathodes, stemming mainly from the difficulties in creating effective lithium ion pathways in high sulfur content electrodes. To develop a high-rate cathode for lithium-sulfur (Li-S) batteries, extenuation of the lithium ion diffusion barrier in thick electrodes is potentially straightforward. Here, a phyllosilicate material with a large interlamellar distance is demonstrated in high-rate cathodes as high sulfur loading. The interlayer space (≈1.396 nm) incorporated into a low lithium ion diffusion barrier (0.155 eV) significantly facilitates lithium ion diffusion within the entire sulfur cathode, and gives rise to remarkable nearly sulfur loading-independent cell performances. When combined with 80% sulfur contents, the electrodes achieve a high capacity of 865 mAh g-1 at 1 mA cm-2 and a retention of 345 mAh g-1 at a high discharging/charging rate of 15 mA cm-2 , with a sulfur loading up to 4 mg. This strategy represents a major advance in high-rate Li-S batteries via the construction of fast ions transfer paths toward real-life applications, and contributes to the research community for the fundamental mechanism study of loading-independent electrode systems.

7.
Small ; 14(5)2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29226523

RESUMO

As anodes of Li-ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g-1 ) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu2 O/CuO/reduced graphene oxides (Cu2 O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single-step hydrothermal method. The Cu2 O/CuO/rGO anode exhibits remarkable cyclic and high-rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g-1 at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.

8.
ACS Nano ; 11(8): 8144-8152, 2017 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-28742326

RESUMO

Lithium-tellurium (Li-Te) batteries are attractive for energy storage owing to their high theoretical volumetric capacity of 2621 mAh cm-3. In this work, highly nanoporous cobalt and nitrogen codoped carbon polyhedra (C-Co-N) derived from a metal-organic framework (MOF) is synthesized and employed as tellurium host for Li-Te batteries. The Te@C-Co-N cathode with a high Te loading of 77.2 wt % exhibits record-breaking electrochemical performances including an ultrahigh initial capacity of 2615.2 mAh cm-3 approaching the theoretical capacity of Te (2621 mAh cm-3), a superior cycling stability with a high capacity retention of 93.6%, a ∼99% Columbic efficiency after 800 cycles as well as rate capacities of 2160, 1327.6, and 894.8 mAh cm-3 at 4, 10, and 20 C, respectively. The redox chemistry of tellurium is revealed by in operando Raman spectroscopic analysis and density functional theory simulations. The results illustrate that the performances are attributed to the highly conductive C-Co-N matrix with an advantageous structure of abundant micropores, which provides highly efficient channels for electron transfer and ionic diffusion as well as sufficient surface area to efficiently host tellurium while mitigating polytelluride dissolution and suppressing volume expansion.

9.
ACS Nano ; 10(12): 10981-10987, 2016 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-28024364

RESUMO

Owing to the high theoretical specific capacity (1166 mAh g-1), lithium sulfide (Li2S) has been considered as a promising cathode material for Li-S batteries. However, the polysulfide dissolution and low electronic conductivity of Li2S limit its further application in next-generation Li-S batteries. In this report, a nanoporous Li2S@C-Co-N cathode is synthesized by liquid infiltration-evaporation of ultrafine Li2S nanoparticles into graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) derived from metal-organic frameworks. The obtained Li2S@C-Co-N architecture remarkably immobilizes Li2S within the cathode structure through physical and chemical molecular interactions. Owing to the synergistic interactions between C-Co-N and Li2S nanoparticles, the Li2S@C-Co-N composite delivers a reversible capacity of 1155.3 (99.1% of theoretical value) at the initial cycle and 929.6 mAh g-1 after 300 cycles, with nearly 100% Coulombic efficiency and a capacity fading of 0.06% per cycle. It exhibits excellent rate capacities of 950.6, 898.8, and 604.1 mAh g-1 at 1C, 2C, and 4C, respectively. Such a cathode structure is promising for practical applications in high-performance Li-S batteries.

10.
ACS Nano ; 10(9): 8837-42, 2016 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-27552580

RESUMO

Three-dimensional aerogel with ultrathin tellurium nanowires (TeNWs) wrapped homogeneously by reduced graphene oxide (rGO) is realized via a facile hydrothermal method. Featured with high conductivity and large flexibility, the rGO constructs a conductive three-dimensional (3D) backbone with rich porosity and leads to a free-standing, binder-free cathode for lithium-tellurium (Li-Te) batteries with excellent electrochemical performances. The cathode shows a high initial capacity of 2611 mAh cm(-3) at 0.2 C, a high retention of 88% after 200 cycles, and a high-rate capacity of 1083 mAh cm(-3) at 10 C. In particular, the 3D aerogel cathode delivers a capacity of 1685 mAh cm(-3) at 1 C after 500 cycles, showing pronounced long-cycle performance at high current density. The performances are attributed to the well-defined flexible 3D architecture with high porosity and conductivity network, which offers highly efficient channels for electron transfer and ionic diffusion while compromising volume expansion of Te in charge/discharge. Owing to such advantageous properties, the reported 3D rGO/tellurium nanowire (3DGT) aerogel presents promising application potentials as a high-performance cathode for Li-Te batteries.

11.
Chemphyschem ; 15(13): 2688-91, 2014 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24954815

RESUMO

In the field of oriented-attachment crystal growth, one-dimensional nanocrystals are frequently employed as building blocks to synthesize two-dimensional or large-aspect-ratio one-dimensional nanocrystals. Despite recent extensive experimental advances, the underlying inter-particle interaction in the synthesis still remains elusive. In this report, using Ag as a platform, we investigate the van der Waals interactions associated with the side-by-side and end-to-end assemblies of one-dimensional nanorods. The size, aspect ratio, and inter-particle separation of the Ag precursor nanorods are found to have dramatically different impacts on the van der Waals interactions in the two types of assemblies. Our work facilitates the fundamental understanding of the oriented-attachment assembling mechanism based on one-dimensional nanocrystals.

12.
Nanoscale ; 6(5): 2531-47, 2014 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-24481078

RESUMO

Since Penn et al. first discovered the oriented attachment growth of crystals, the oriented attachment mechanism has now become a major research focus in the crystal field, and extensive efforts have been carried out over the past decade to systematically investigate the growth mechanism and the statistical kinetic models. However, most of the work mainly focuses on the experimental results on the oriented attachment growth. In contrast to the previous reviews, our review provides an overview of the recent theoretical advances in oriented attachment kinetics combined with experimental evidences. After a brief introduction to the van der Waals interaction and Coulombic interaction in a colloidal system, the correlation between the kinetic models of oriented attachment growth and the interactions is then our focus. The impact of in situ experimental observation techniques on the study of oriented attachment growth is examined with insightful examples. In addition, the advances in theoretical simulations mainly investigating the thermodynamic origin of these interactions at the atomic level are reviewed. This review seeks to understand the oriented attachment crystal growth from a kinetic point of view and provide a quantitative methodology to rationally design an oriented attachment system with pre-evaluated crystal growth parameters.

13.
J Nanosci Nanotechnol ; 11(9): 7700-8, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22097476

RESUMO

Cubic nanocrystal and hexagonal micro-rods NaYF4, with predictable size, shape and phase, have been successfully synthesized through hydrothermal reaction. The growth mechanism and the effect of mass transfer on the morphology of hexagonal micro-prism are both discussed in detail. The increase of tri-doping lanthanide ion concentration decreased the size of crystal particle, which was explained by the Arrhenius rate equation together combined with the Gibbs-Thomson relationship. Furthermore, the dopants did not only affect the sizes of tri-doped NaYF4 micro-rods, but also impacted upon fluorescence intensity. The fluorescence of tri-doped NaYF4: Nd3+/Yb3+/Er3+ system, excited by an 800 nm femtolaser, was intensified with the increase of doped lanthanide ions concentration. Nevertheless owing to the fluorescence quenching, the other two systems (NaYF4: Nd3+/Ho3+/Er3+ and NaYF4: Nd3+/Tm3+/Er3+) did not show the same phenomenon.

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