A simple and scalable method to fabricate graphene‐cellulose paper (GCP) membranes is reported; these membranes exhibit great advantages as freestanding and binder‐free electrodes for flexible ...supercapacitors. The GCP electrode consists of a unique three‐dimensional interwoven structure of graphene nanosheets and cellulose fibers and has excellent mechanical flexibility, good specific capacitance and power performance, and excellent cyclic stability. The electrical conductivity of the GCP membrane shows high stability with a decrease of only 6% after being bent 1000 times. This flexible GCP electrode has a high capacitance per geometric area of 81 mF cm−2, which is equivalent to a gravimetric capacitance of 120 F g−1 of graphene, and retains >99% capacitance over 5000 cycles. Several types of flexible GCP‐based polymer supercapacitors with various architectures are assembled to meet the power‐energy requirements of typical flexible or printable electronics. Under highly flexible conditions, the supercapacitors show a high capacitance per geometric area of 46 mF cm−2 for the complete devices. All the results demonstrate that polymer supercapacitors made using GCP membranes are versatile and may be used for flexible and portable micropower devices.
Graphene–cellulose paper (GCP) membrane materials fabricated by simple vacuum filtration are used as electrodes for flexible supercapacitors. The unique three‐dimensional interwoven structure of graphene nanosheets and cellulose fibers equips the GCP with excellent mechanical flexibility, high rate capability and capacitance per geometric area of 81 mF cm−2, and long cycling stability. GCP‐based flexible polymer supercapacitors with various architectures are demonstrated.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Au–Ni core‐shell nanorods (NRs) and Au–Pt–Ni core‐sandwich‐shell NRs are synthesized and exhibit high activity for selective H2O2 production via direct oxygen reduction. The epitaxial growth with ...coherent lattice fringes allow for the tuning of the oxygen reduction pathway. Moreover, a selectivity of 95% and mass activity of 192.9 A g−1noble metal are achieved using Au–Pt–Ni NRs at 150 mV overpotential.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Ether based electrolytes have surfaced as alternatives to conventional carbonates allowing for enhanced electrochemical performance of sodium-ion batteries; however, the primary source of the ...improvement remains poorly understood. Here we show that coupling titanium dioxide and other anode materials with diglyme does enable higher efficiency and reversible capacity than those for the combination involving ester electrolytes. Importantly, the electrolyte dependent performance is revealed to be the result of the different structural evolution induced by a varied sodiation depth. A suit of characterizations show that the energy barrier to charge transfer at the interface between electrolyte and electrode is the factor that dominates the interfacial electrochemical characteristics and therefore the energy storage properties. Our study proposes a reliable parameter to assess the intricate sodiation dynamics in sodium-ion batteries and could guide the design of aprotic electrolytes for next generation rechargeable batteries.
Non‐precious Fe/N co‐modified carbon electrocatalysts have attracted great attention due to their high activity and stability in oxygen reduction reaction (ORR). Compared to iron‐free N‐doped carbon ...electrocatalysts, Fe/N‐modified electrocatalysts show four‐electron selectivity with better activity in acid electrolytes. This is believed relevant to the unique Fe–N complexes, however, the Fe–N structure remains unknown. We used o,m,p‐phenylenediamine as nitrogen precursors to tailor the Fe–N structures in heterogeneous electrocatalysts which contain FeS and Fe3C phases. The electrocatalysts have been operated for 5000 cycles with a small 39 mV shift in half‐wave potential. By combining advanced electron microscopy and Mössbauer spectroscopy, we have identified the electrocatalytically active Fe–N6 complexes (FeN6, FeIII(porphyrin)(pyridine)2). We expect the understanding of the FeN6 structure will pave the way towards new advanced Fe–N based electrocatalysts.
The active FeNx sites in Fe/N/C catalysts were identified by electron microscopy and Mössbauer spectroscopy as the six‐coordinate FeIII species FeIII(porphyrin)(pyridine)2. The results lead the way to target‐specific synthesis of highly active and stable non‐precious metal catalysts for oxygen reduction reaction.
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A unique sandwich structure is designed with pure sulfur between two graphene membranes, which are continuously produced over a large area, as a very simple but effective approach for the fabrication ...of Li–S batteries with ultrafast charge/discharge rates and long lifetimes.
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Despite the outstanding gravimetric performance of lithium–sulfur (Li–S) batteries, their practical volumetric energy density is normally lower than that of lithium‐ion batteries, mainly due to the ...low density of nanostructured sulfur as well as the porous carbon hosts. Here, a novel approach is developed to fabricate high‐density graphene bulk materials with “ink‐bottle‐like” mesopores by phosphoric acid (H3PO4) activation. These pores can effectively confine the polysulfides due to their unique structure with a wide body and narrow neck, which shows only a 0.05% capacity fade per cycle for 500 cycles (75% capacity retention) for accommodating polysulfides. With a density of 1.16 g cm−3, a hybrid cathode containing 54 wt% sulfur delivers a high volumetric capacity of 653 mA h cm−3. As a result, a device‐level volumetric energy density as high as 408 W h L−1 is achieved with a cathode thickness of 100 µm. This is a periodic yet practical advance to improve the volumetric performance of Li–S batteries from a device perspective. This work suggests a design principle for the real use Li–S batteries although there is a long way ahead to bridge the gap between Li–S batteries and Li–ion batteries in volumetric performance.
High‐density graphene monolith with “ink‐bottle‐like” pores was prepared by H3PO4 activation together with a capillary evaporation‐induced drying method. These pores can effectively accommodate and confine the lithium polysulfides with their wide body and narrow neck, respectively. When used as a carbon host for a Li–S battery, the device exhibits a high volumetric energy density and long‐cycle life.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A flexible Li–S battery based on an integrated structure of sulfur and graphene on a separator is developed. The internal graphene current collector offers a continuous conductive pathway, a modified ...interface with sulfur, and a good barrier to and an effective reservoir for dissolved polysulfides, consequently improving the capacity and cyclic life of the Li–S battery.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Ageing, an unanswered question in the medical field, is a multifactorial process that results in a progressive functional decline in cells, tissues and organisms. Although it is impossible to prevent ...ageing, slowing down the rate of ageing is entirely possible to achieve. Traditional Chinese medicine (TCM) is characterized by the nourishing of life and its role in anti‐ageing is getting more and more attention. This article summarizes the work done on the natural products from TCM that are reported to have anti‐ageing effects, in the past two decades. The effective anti‐ageing ingredients identified can be generally divided into flavonoids, saponins, polysaccharides, alkaloids and others. Astragaloside, Cistanche tubulosa acteoside, icariin, tetrahydrocurcumin, quercetin, butein, berberine, catechin, curcumin, epigallocatechin gallate, gastrodin, 6‐Gingerol, glaucarubinone, ginsenoside Rg1, luteolin, icarisid II, naringenin, resveratrol, theaflavin, carnosic acid, catalpol, chrysophanol, cycloastragenol, emodin, galangin, echinacoside, ferulic acid, huperzine, honokiol, isoliensinine, phycocyanin, proanthocyanidins, rosmarinic acid, oxymatrine, piceid, puerarin and salvianolic acid B are specified in this review. Simultaneously, chemical structures of the monomers with anti‐ageing activities are listed, and their source, model, efficacy and mechanism are also described. The TCMs with anti‐ageing function are classified according to their action pathways, including the telomere and telomerase, the sirtuins, the mammalian target of rapamycin, AMP‐activated kinase and insulin/insulin‐like growth factor‐1 signalling pathway, free radicals scavenging and the resistance to DNA damage. Finally, Chinese compound prescription and extracts related to anti‐ageing are introduced, which provides the basis and the direction for the further development of novel and potential drugs.
Linked Articles
This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Rational design and synthesis of 2D organic–inorganic hybrid materials is important for transformative technological advances for energy storage. Here, a 2D conductive hybrid lamella and its ...intercalation properties for thin‐film supercapacitors are reported. The 2D organic–inorganic hybrid lamella comprises periodically stacked 2D nanosheets with 11.81 Å basal spacing, and is electronically conductive (605 S m−1). In contrast to the pre‐existing organic‐based 2D materials, this material has extremely low gas‐permeable porosity (16.5 m2 g−1) in contrast to the high ionic accessibility. All these structural features collectively contribute to the high capacitances up to 732 F cm−3, combined with small structural swelling at as low as 4.8% and good stability. At a discharge time of 6 s, the thin‐film intercalation electrode delivers an energy density of 24 mWh cm−3, which universally outperforms the surface‐dominant capacitive processes in porous carbons.
A layer‐structured organic–inorganic hybrid material with large lamellar period (11.81 Å), and good electrical conductivity (605 S m−1) is facilely self‐assembled into thin films on various conductive or insulating, and hydrophobic or hydrophilic, surfaces (metals, plastic, carbon, and glass), showing extraordinary volumetric capacitance up to 732 F cm−3 in aqueous salt solutions, with only 4.8–10.3% interlayer expansion.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The BiVO
4
material has attracted much attention in recent years due to its active photocatalytic properties under visible light, bright yellow color as a nontoxic pigment, and its high relative ...permittivity (
r
) and
Qf
(quality factor,
Q
× resonant frequency,
f
) as a potential microwave dielectric ceramic. In this review, we introduce the origin, synthesis, crystal structure and phase transitions of the four polymorphic phases of BiVO
4
: orthorhombic (pucherite), zircon (dreyerite), scheelite monoclinic (clinobisvanite) and scheelite tetragonal. We then precis recent studies on doped BiVO
4
ceramics in terms of A site, B site and A/B site complex substitutions. Low sintering temperature (<800 °C) and high
r
values could be obtained in some solid solution ceramics and near zero temperature coefficient of resonant frequency (TCF/
τ
f
) values could be achieved in layered or granulated particle composite ceramics. Besides, a series of temperature stable high
r
microwave dielectric ceramics can also be obtained for many co-fired composite ceramics, such as BiVO
4
-TiO
2
, and BiVO
4
-TiO
2
-Bi
2
Ti
4
O
11
. The high
r
, high
Qf
value, low sintering temperature and chemical compatibility with some base metals suggest that BiVO
4
-based materials are strong candidates for both LTCC and other microwave device applications in current 4G and future 5G technologies.
We precis recent studies on doped BiVO
4
ceramics in terms of A site, B site and A/B site complex substitutions. Low sintering temperature (<800 °C), high
r
and near zero temperature coefficient values could be obtained in solid solution and composite ceramics.
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