Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
ACS Appl Mater Interfaces ; 12(5): 5909-5919, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31944646

RESUMO

Effective hosts of sulfur are essential for the application of lithium-sulfur batteries. However, various refined nanomaterials or carbon-based hosts possess low density, high surface area, and large porosity, leading to undesirable reduction on both gravimetric and volumetric energy densities. Herein, spherical metal oxides with high tap density are introduced as carbon-free hosts of sulfur for the first time. The ternary oxides show a superior synergistic effect of adsorption and electrocatalytic conversion of soluble intermediate polysulfides. Besides, oxide microspheres can build stable conductive frameworks and open channels in porous electrodes for fast transport of electrons and active diffusion of electrolyte. Such a synergistic effect and unique structural feature of porous electrodes are favorable for achieving good utilization and stable cycle performance of the sulfur cathode. Typically, the S/LiNi0.8Co0.1Mn0.1O2 composite exhibits good cycle stability with a low capacity decay rate (0.057% per cycle) during 500 cycles at 0.1 C. Importantly, due to the high tap density (1.81 g cm-3), the S/LiNi0.8Co0.1Mn0.1O2 composite delivers a larger volumetric capacity (1601.9 mAh cm-3-composite), almost 2.3 times of S/carbon composite (689.4 mAh cm-3-composite). Therefore, this work provides a feasible strategy to reach long life and high volumetric capacity of cathode based on metal oxides as sulfur hosts.

2.
Adv Mater ; 32(3): e1806478, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31116898

RESUMO

It is undoubtable that the use of solar energy will continue to increase. Solar cells that convert solar energy directly to electricity are one of the most convenient and important photoelectric conversion devices. Though silicon-based solar cells and thin-film solar cells have been commercialized, developing low-cost and highly efficient solar cells to meet future needs is still a long-term challenge. Some emerging solar-cell types, such as dye-sensitized and perovskite, are approaching acceptable performance levels, but their costs remain too high. To obtain a higher performance-price ratio, it is necessary to find new low-cost counter materials to replace conventional precious metal electrodes (Pt, Au, and Ag) in these emerging solar cells. In recent years, the number of counter-electrode materials available, and their scope for further improvement, has expanded for dye-sensitized and perovskite solar cells. Generally regular patterns in the intrinsic features and structural design of counter materials for emerging solar cells, in particular from an electrochemical perspective and their effects on cost and efficiency, are explored. It is hoped that this recapitulative analysis will help to make clear what has been achieved and what still remains for the development of cost-effective counter-electrode materials in emerging solar cells.

3.
Adv Sci (Weinh) ; 6(15): 1900620, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31406674

RESUMO

Solar cells and rechargeable batteries are two key technologies for energy conversion and storage in modern society. Here, an integrated solar-driven rechargeable lithium-sulfur battery system using a joint carbon electrode in one structure unit is proposed. Specifically, three perovskite solar cells are assembled serially in a single substrate to photocharge a high energy lithium-sulfur (Li-S) battery, accompanied by direct conversion of the solar energy to chemical energy. In the subsequent discharge process, the chemical energy stored in the Li-S battery is further converted to electrical energy. Therefore, the newly designed battery is capable of achieving solar-to-chemical energy conversion under solar-driven conditions, and subsequently delivering electrical energy from the stored chemical energy. With an optimized structure design, a high overall energy conversion efficiency of 5.14% is realized for the integrated battery. Moreover, owing to the self-adjusting photocharge advantage, the battery system can retain high specific capacity up to 762.4 mAh g-1 under a high photocharge rate within 30 min, showing an effective photocharging feature.

4.
Nat Commun ; 10(1): 2842, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31253800

RESUMO

Metal halide perovskite semiconductors possess outstanding characteristics for optoelectronic applications including but not limited to photovoltaics. Low-dimensional and nanostructured motifs impart added functionality which can be exploited further. Moreover, wider cation composition tunability and tunable surface ligand properties of colloidal quantum dot (QD) perovskites now enable unprecedented device architectures which differ from thin-film perovskites fabricated from solvated molecular precursors. Here, using layer-by-layer deposition of perovskite QDs, we demonstrate solar cells with abrupt compositional changes throughout the perovskite film. We utilize this ability to abruptly control composition to create an internal heterojunction that facilitates charge separation at the internal interface leading to improved photocarrier harvesting. We show how the photovoltaic performance depends upon the heterojunction position, as well as the composition of each component, and we describe an architecture that greatly improves the performance of perovskite QD photovoltaics.

5.
ACS Appl Mater Interfaces ; 11(16): 14830-14839, 2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-30945528

RESUMO

High-Ni layered oxides are potential cathodes for high energy Li-ion batteries due to their large specific capacity advantage. However, the fast capacity fade by undesirable structural degradation in liquid electrolyte during long-term cycling is a stumbling block for the commercial application of high-Ni oxides. In this work, a functional gel polymer electrolyte, grafted with sodium alginate, is introduced to increase the stability of high-Ni oxide cathodes at the levels of both the particle and electrode. An in situ generated ion-conducting layer appears on the interface through the chemical interaction between transition-metal cations of the cathode and the metalophilic reticulum group in sodium alginate. Such a tailoring layer can not only enhance the interfacial compatibility on the cathode/electrolyte interface, reducing the interfacial resistance, but also inhibit the HF corrosion, suppressing the dissolution of transition-metal cations and harmful gradient distribution of components through the oxide cathode at the electrode level. Meanwhile, detrimental microcracks in oxide microspheres and between primary crystallites are impressively inhibited at the particle level. The high-Ni oxide cathode with the metalophilic gel polymer electrolyte shows excellent cycle stability with large initial capacity of 204.9 mA h g-1 at a 1.0 C rate and high discharge capacity retention within 300 cycles at high temperature.

6.
ACS Appl Mater Interfaces ; 10(10): 8749-8757, 2018 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-29469561

RESUMO

Low sulfur utilization and poor cycle life of the sulfur cathode with high sulfur loadings remain a great challenge for lithium-sulfur (Li-S) battery. Herein, the free-standing carbon film consisting of porous carbon nanofibers (PCNFs) and carbon nanotubes (CNTs) is successfully fabricated by the electrospinning technology. The PCNF/CNT film with three-dimensional and interconnected structure is promising for the uniformity of the high-loading sulfur, good penetration of the electrolyte, and reliable accommodation of volumetric expansion of the sulfur cathode. In addition, the abundant N/O-doped elements in PCNF/CNT film are helpful to chemically trap soluble polysulfides in the charge-discharge processes. Consequently, the obtained monolayer S/PCNF/CNT film as the cathode shows high specific capacity, excellent cycle stability, and rate stability with the sulfur loading of 3.9 mg cm-2. Moreover, the high areal capacity of 13.5 mA h cm-2 is obtained for the cathode by stacking three S/PCNF/CNT layers with the high sulfur loading of 12 mg cm-2. The stacking-layered cathode with high sulfur loading provides excellent cycle stability, which is beneficial to fabricate high-energy-density Li-S battery in future.

7.
ACS Appl Mater Interfaces ; 8(46): 31684-31694, 2016 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-27805807

RESUMO

The lithium-sulfur (Li-S) battery is expected to be the high-energy battery system for the next generation. Nevertheless, the degradation of lithium anode in Li-S battery is the crucial obstacle for practical application. In this work, a porous carbon paper obtained from corn stalks via simple treating procedures is used as interlayer to stabilize the surface morphology of Li anode in the environment of Li-S battery. A smooth surface morphology of Li is obtained during cycling by introducing the porous carbon paper into Li-S battery. Meanwhile, the electrochemical performance of sulfur cathode is partially enhanced by alleviating the loss of soluble intermediates (polysulfides) into the electrolyte, as well as the side reaction of polysulfides with metallic lithium. The Li-S battery assembled with the interlayer exhibits a large capacity and excellent capacity retention. Therefore, the porous carbon paper as interlayer plays a bifunctional role in stabilizing the Li anode and enhancing the electrochemical performance of the sulfur cathode for constructing a stable Li-S battery.

8.
Biochem Biophys Res Commun ; 478(3): 1165-72, 2016 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-27544030

RESUMO

microRNAs (miRNAs) are short noncoding RNAs that function in RNA silencing and post-transcriptional regulation of gene expression. They play critical regulatory roles in many cardiovascular diseases, including ischemia-induced cardiac injury. Here, we report microRNA-22, highly expressed in the heart, can protect cardiomyocytes from starvation-induced injury through promoting autophagy and inhibiting apoptosis. Quantitative real-time PCR (qPCR) demonstrated that the expression of miR-22 in starvation-treated neonatal rat cardiomyocytes (NRCMs) was markedly down-regulated. Over-expression of miR-22 significantly promoted starvation-induced autophagy and inhibited starvation-induced apoptosis in NRCMs. In contrast, reduction of miR-22 suppressed autophagy and accelerated apoptosis in starving NRCMs. Immunohistochemistry and TUNEL staining results also provided further evidence that miR-22 promoted autophagy and inhibited apoptosis in myocardial cells. Furthermore, both luciferase reporter assay and western blot analysis were performed to identify p38α as a direct target of miR-22. Taken together, miR-22 plays an important role in regulating autophagy and apoptosis in ischemic myocardium through targeting p38α. miR-22 may represent a potential therapeutic target for the treatment of ischemic heart diseases.


Assuntos
Apoptose , Autofagia , MicroRNAs/metabolismo , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Animais Recém-Nascidos , Sequência de Bases , Citoproteção , Regulação da Expressão Gênica , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Modelos Biológicos , Ratos Sprague-Dawley
9.
ACS Appl Mater Interfaces ; 8(12): 7783-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26981849

RESUMO

Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

10.
ChemSusChem ; 6(5): 802-6, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23559517

RESUMO

Storable sunshine, reusable rays: A solar rechargeable redox flow battery is proposed based on the photoregeneration of I(3)(-)/I(-) and [Fe(C(10)H(15))(2)](+)/Fe(C(10)H(15))(2) soluble redox couples, which can be regenerated by flowing from a discharged redox flow battery (RFB) into a dye-sensitized solar cell (DSSC) and then stored in tanks for subsequent RFB applications This technology enables effective solar-to-chemical energy conversion.


Assuntos
Fontes de Energia Elétrica , Energia Solar , Eletrodos , Iodo/química , Oxirredução , Titânio/química
12.
Langmuir ; 22(13): 5867-71, 2006 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-16768521

RESUMO

The selective depositions of MoS2 and MoO2 over Ni surfaces are demonstrated on Ni/TiO2 particles in a mild electroless deposition process. High-resolution transmission electron microscopy (HRTEM) images show the uniform distribution of 10-30 nm spherical and hemispherical Ni particles on TiO2 surface, and three to six layers of MoS2 on the surface of Ni particles. The as-prepared MoS2-Ni/TiO2 is used as a catalyst for the hydrodesulfurization (HDS) reaction of dibenzothiophene (DBT), and shows a significant increase over commercial catalysts in turnover frequencies as the result of unique distribution of active components in the binary catalyst. The selective material deposition is explained in the context of Ni catalyzed KBH4 decomposition, which produces strong reducing species responsible for the site selective deposition of Mo. The synthetic method can be potentially used to prepare bimetallic materials with similar nanostructures such as those of Mo-Co, Mo-Pd, and Mo-Rh.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA