{Cu6(pybz)8(OH)2·I5 –·I7 –} n (1), obtained hydrothermally by using iodine molecules as a versatile precursor template, consists of a cationic framework with two types of zigzag channels, which ...segregate I5 – and I7 – anions. The framework exhibits the first observed bipillared-bilayer structure featuring both interdigitation and interpenetration. 1 displays high framework stability in both acidic (HCl) and alkaline (NaOH) solutions. 1 slowly releases iodine in dry methanol to give Cu6(pybz)8(OH)2(I–)2·3.5CH3OH (1′) and partially recovers iodine from cyclohexane to form Cu6(pybz)8(OH)2(I–)2·xI2 (1″). Differences of up to 100 times in electrical conductivity and of 4 times in nonlinear optical activity (NLO) have been measured between 1 and 1′. This compound is one of few displaying multifunctionality, electrical conductivity, NLO, and crystal–crystal stability upon release and recovery of iodine. It is also unique in the iodine release from polyiodide anions in a metal–organic framework.
Iron arsenide superconductors based on the material LaFeAsO(1-x)F(x) are characterized by a two-dimensional Fermi surface (FS) consisting of hole and electron pockets yielding structural and ...antiferromagnetic transitions at x=0. Electron doping by substituting O(2-) with F(-) suppresses these transitions and gives rise to superconductivity with a maximum T(c) of 26 K at x=0.1. However, the over-doped region cannot be accessed due to the poor solubility of F(-) above x=0.2. Here we overcome this problem by doping LaFeAsO with hydrogen. We report the phase diagram of LaFeAsO(1-x)H(x) (x<0.53) and, in addition to the conventional superconducting dome seen in LaFeAsO(1-x)F(x), we find a second dome in the range 0.21<x<0.53, with a maximum T(c) of 36 K at x=0.3. Density functional theory calculations reveal that the three Fe 3d bands (xy, yz and zx) become degenerate at x=0.36, whereas the FS nesting is weakened monotonically with x. These results imply that the band degeneracy has an important role to induce high T(c).
Wearable and highly sensitive strain sensors are essential components of electronic skin for future biomonitoring and human machine interfaces. Here we report a low-cost yet efficient strategy to ...dope polyaniline microparticles into gold nanowire (AuNW) films, leading to 10 times enhancement in conductivity and ∼8 times improvement in sensitivity. Simultaneously, tattoolike wearable sensors could be fabricated simply by a direct “draw-on” strategy with a Chinese penbrush. The stretchability of the sensors could be enhanced from 99.7% to 149.6% by designing curved tattoo with different radius of curvatures. We also demonstrated roller coating method to encapusulate AuNWs sensors, exhibiting excellent water resistibility and durability. Because of improved conductivity of our sensors, they can directly interface with existing wireless circuitry, allowing for fabrication of wireless flexion sensors for a human finger-controlled robotic arm system.
Dielectrophoresis is used to align carbon nanotubes (CNTs) within gelatin methacrylate (GelMA) hydrogels in a facile and rapid manner. Aligned GelMA‐CNT hydrogels show higher electrical properties ...compared with pristine and randomly distributed CNTs in GelMA hydrogels. The muscle cells cultured on these materials demonstrate higher maturation compared with cells cultured on pristine and randomly distributed CNTs in GelMA hydrogels.
Capacitive deionization (CDI) is considered a promising technology for desalination of sea or brackish water. In this study, a ZnS/g-C
N
composite was synthesized through a one-step high-temperature ...method and used as the main material to fabricate CDI electrodes. The results of SEM and TEM showed that spherical-like nanoparticles of ZnS were uniformly distributed on the g-C
N
sheet. The g-C
N
phase facilitates the ZnS particles precipitate and restrain their agglomeration, which contributes to a high specific surface area of ZnS. Furthermore, the electrochemical test results indicated that ZnS/g-C
N
composite had a good capacitance characteristic, low resistance, and high electrochemical stability. Finally, the desalinization performance of the ZnS/g-C
N
composite electrodes was tested in traditional mode and membrane capacitive deionization (MCDI) mode. The results showed that ZnS/g-C
N
//ZnS/g-C
N
(MCDI) exhibited an optimal desalination capacity. The adsorption amount was 27.65, 50.26, and 65.34 mg/g for NaCl initial concentration of 200, 400, and 600 mg/L, respectively, with the voltage of 1.2 V and flow rate of 5 mL/min. Increasing initial concentration enhanced the conductivity and ion migration rate so as to increase the NaCl adsorption amount. ZnS/g-C
N
composite can be used as potential electrode material for high performance of MCDI.
Hydrogels with prominent flexibility, versatility, and high sensitivity play an important role in the design and fabrication of wearable sensors. In particular, these flexible conductive hydrogels ...exhibit elastic modulus that is highly compatible with human skin, demonstrating the great potential for flexible sensing. However, the preparation of high-performance hydrogel-based sensors that can restrain extreme cold conditions is still challenging. Herein, a novel anti-freezing composite hydrogel with superior conductivity based on polyacrylamide (PAM), LiCl, and PEDOT:PSS coated cellulose nanofibrils (PAM/PEDOT:PSS/CNF) is constructed. The addition of CNF increased the hydrogen bonding sites of the molecular chains in the micro, thus improving the mechanical strength and the conductivity of the hydrogel in the macro. The hydrogels achieve a high tensile strength of 0.19 MPa, compressive strength of 0.92 MPa, and dissipation energy of 41.9 kJ/m3. Otherwise, LiCl increases the interactions between the colloidal phase and water molecules, endowing the hydrogels with excellent freezing tolerance. Specifically, the optimized hydrogel of 45 % LiCl exhibited stable mechanical properties at −40 °C. Finally, the composite hydrogel was used to assemble flexible sensors with high sensitivity of 10.3 MPa−1, which can detect a wide range of human movements and physiological activities.
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Conducting polymers are promising material candidates in diverse applications including energy storage, flexible electronics, and bioelectronics. However, the fabrication of conducting polymers has ...mostly relied on conventional approaches such as ink-jet printing, screen printing, and electron-beam lithography, whose limitations have hampered rapid innovations and broad applications of conducting polymers. Here we introduce a high-performance 3D printable conducting polymer ink based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for 3D printing of conducting polymers. The resultant superior printability enables facile fabrication of conducting polymers into high resolution and high aspect ratio microstructures, which can be integrated with other materials such as insulating elastomers via multi-material 3D printing. The 3D-printed conducting polymers can also be converted into highly conductive and soft hydrogel microstructures. We further demonstrate fast and streamlined fabrications of various conducting polymer devices, such as a soft neural probe capable of in vivo single-unit recording.
In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect ...absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.
The silk road: By employing silk fibroin as a binder between graphene oxide films and aluminum foil for a facile, highly localized reduction process, conductive paper is reinvented. The flexible, ...robust biographene papers have high toughness and electrical conductivity. This electrochemical written‐in approach is readily applicable for the fabrication of conductive patterned papers (see picture) with complex circuitries.
Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive ...detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10-100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa(-1) in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas.
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