Recently, interest in aluminium ion batteries with aluminium anodes, graphite cathodes and ionic liquid electrolytes has increased; however, much remains to be done to increase the cathode capacity ...and to understand details of the anion-graphite intercalation mechanism. Here, an aluminium ion battery cell made using pristine natural graphite flakes achieves a specific capacity of ∼110 mAh g
with Coulombic efficiency ∼98%, at a current density of 99 mA g
(0.9 C) with clear discharge voltage plateaus (2.25-2.0 V and 1.9-1.5 V). The cell has a capacity of 60 mAh g
at 6 C, over 6,000 cycles with Coulombic efficiency ∼ 99%. Raman spectroscopy shows two different intercalation processes involving chloroaluminate anions at the two discharging plateaus, while C-Cl bonding on the surface, or edges of natural graphite, is found using X-ray absorption spectroscopy. Finally, theoretical calculations are employed to investigate the intercalation behaviour of choloraluminate anions in the graphite electrode.
The recent emergence of topological insulators in condensed matter physics has inspired analogous wave phenomena in mechanical systems. However, to date, the design of these mechanical systems has ...been limited mostly to discrete lattices or perforated structures. Here, we take a ubiquitous design of a bolted elastic plate and demonstrate that it can guide flexural waves crisply around sharp bends. We show that this continuum system eliminates unwanted in-plane plate modes and allows the manipulation of low-frequency flexural modes by exploiting the local resonance of the bolts. We report the existence of a pair of double Dirac cones near the resonant frequency of the bolts, one of which leads to the creation of a topological complete bandgap that forbids all the plate modes. These findings open new possibilities of managing multiple wave modes in elastic solids for applications in energy harvesting, impact mitigation, and structural health monitoring.
The high efficiency of precursor-to-perovskite conversion is one of the core factors in boosting the performance of perovskite solar cells (PSCs). Herein, we report a liquid/liquid interfacial ...synthesis of terpyridine-zinc(
ii
) (ZnTPY) coordination nanosheets (CONASHs), which can enhance PbI
2
-based perovskite crystallization and thus the efficiency of PSCs. Ultrasonically fragmented ZnTPY CONASHs, rich in uncoordinated terpyridine moieties, caused multidentate chelation with PbI
2
, resulting in a well-dispersed ZnTPY:PbI
2
complex. This metal-organic complex could act as a heterogeneous nucleation seed and facilitate the formation of a PbI
2
-to-PbI
6−
x
4−
coordinated octahedral framework in a precursor solution of perovskite, thereby reducing the crystallization barrier of tetragonal CH
3
NH
3
PbI
3
perovskites and achieving a complete precursor-to-perovskite conversion. Consequently, ZnTPY-capped perovskite crystals had a long photoluminescence (PL) lifetime, which is attributed to the more passivated trap states associated with ZnTPY. The corresponding PSCs exhibited an optimal power conversion efficiency of 19.8% compared with 17.9% of the controlled device. The results prove that the performance of PSC families can be improved by dispersing PbI
2
in a solution with CONASHs for enhancing the PbI
2
-to-perovskite conversion.
ZnTPY-chelated PbI
2
nuclei effectively reduce the activation energy of perovskite crystallization resulting in higher conversion of PbI
2
into uniform perovskite crystalline films, which ultimately improves the performance of perovskite solar cells.
Hydrogen evolution reaction (HER) from water through electrocatalysis using cost-effective materials to replace precious Pt catalysts holds great promise for clean energy technologies. In this work ...we developed a highly active and stable catalyst containing Co doped earth abundant iron pyrite FeS2 nanosheets hybridized with carbon nanotubes (Fe1–x Co x S2/CNT hybrid catalysts) for HER in acidic solutions. The pyrite phase of Fe1–x Co x S2/CNT was characterized by powder X-ray diffraction and absorption spectroscopy. Electrochemical measurements showed a low overpotential of ∼0.12 V at 20 mA/cm2, small Tafel slope of ∼46 mV/decade, and long-term durability over 40 h of HER operation using bulk quantities of Fe0.9Co0.1S2/CNT hybrid catalysts at high loadings (∼7 mg/cm2). Density functional theory calculation revealed that the origin of high catalytic activity stemmed from a large reduction of the kinetic energy barrier of H atom adsorption on FeS2 surface upon Co doping in the iron pyrite structure. It is also found that the high HER catalytic activity of Fe0.9Co0.1S2 hinges on the hybridization with CNTs to impart strong heteroatomic interactions between CNT and Fe0.9Co0.1S2. This work produces the most active HER catalyst based on iron pyrite, suggesting a scalable, low cost, and highly efficient catalyst for hydrogen generation.
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IJS, KILJ, NUK, PNG, UL, UM
A unique “clean‐lifting transfer” (CLT) technique that applies a controllable electrostatic force to transfer large‐area and high‐quality CVD‐grown graphene onto various rigid or flexible substrates ...is reported. The CLT technique without using any organic support or adhesives can produce residual‐free graphene films with large‐area processability, and has great potential for future industrial production of graphene‐based electronics or optoelectronics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Organic–inorganic hybrid two-dimensional (2D) perovskites have recently attracted great attention in optical and optoelectronic applications due to their inherent natural quantum-well structure. We ...report the growth of high-quality millimeter-sized single crystals belonging to homologous two-dimensional (2D) hybrid organic–inorganic Ruddelsden–Popper perovskites (RPPs) of (BA)2(MA) n −1Pb n I3 n +1 (n = 1, 2, and 3) by a slow evaporation at a constant-temperature (SECT) solution-growth strategy. The as-grown 2D hybrid perovskite single crystals exhibit excellent crystallinity, phase purity, and spectral uniformity. Low-threshold lasing behaviors with different emission wavelengths at room temperature have been observed from the homologous 2D hybrid RPP single crystals. Our result demonstrates that solution-growth homologous organic–inorganic hybrid 2D perovskite single crystals open up a new window as a promising candidate for optical gain media.
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Go for gold: As‐prepared insulin–Au nanoclusters (NCs) show intense red fluorescence, excellent biocompatibility, and preservation of natural insulin bioactivity in lowering the blood‐glucose level. ...Their versatility in applications is demonstrated by fluorescence imaging, X‐ray computed tomography, and insulin–inhibitor interactions (see picture; IDE=insulin‐degrading enzyme).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
High‐performance MoS2 transistors are developed using atomic hexagonal boron nitride as a tunneling layer to reduce the Schottky barrier and achieve low contact resistance between metal and MoS2. ...Benefiting from the ultrathin tunneling layer within 0.6 nm, the Schottky barrier is significantly reduced from 158 to 31 meV with small tunneling resistance.
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The filament in aAu/Ta2O5/Au system is analyzed and determined to be a nanoscaled TaO2−x filament. A shrunken anode localizes the filament formation and the defect boundary leads to faster ...accumulation of oxygen vacancies. The defect changes the switching domination between electron transport and oxygen‐vacancy migration. The migration of oxygen vacancies limits the filament dynamics, indicating the crucial role played by oxygen defects.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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