Electric double layer capacitors (or supercapacitors) store charges through the physisorption of electrolyte ions onto porous carbon electrodes. The control over structure and morphology of carbon ...electrode materials is therefore an effective strategy to render them high surface area and efficient paths for ion diffusion. Here we demonstrate the fabrication of highly porous graphene-derived carbons with hierarchical pore structures in which mesopores are integrated into macroporous scaffolds. The macropores were introduced by assembling graphene-based hollow spheres, and the mesopores were derived from the chemical activation with potassium hydroxide. The unique three-dimensional pore structures in the produced graphene-derived carbons give rise to a Brunauer–Emmett–Teller surface area value of up to 3290 m2 g–1 and provide an efficient pathway for electrolyte ions to diffuse into the interior surfaces of bulk electrode particles. These carbons exhibit both high gravimetric (174 F g–1) and volumetric (∼100 F cm–3) specific capacitance in an ionic liquid electrolyte in acetonitrile. The energy density and power density of the cell assembled with this carbon electrode are also high, with gravimetric values of 74 Wh kg–1 and 338 kW kg–1 and volumetric values of 44 Wh L–1 and 199 kW L–1, respectively. The supercapacitor performance achieved with these graphene-derived carbons is attributed to their unique pore structure and makes them potentially promising for diverse energy storage devices.
The fabrication and design principles for using silver‐nanowire (AgNW) networks as transparent electrodes for flexible film heaters are described. For best practice, AgNWs are synthesized with a ...small diameter and network structures of the AgNW films are optimized, demonstrating a favorably low surface resistivity in transparent layouts with a high figure‐of‐merit value. To explore their potential in transparent electrodes, a transparent film heater is constructed based on uniformly interconnected AgNW networks, which yields an effective and rapid heating of the film at low input voltages. In addition, the AgNW‐based film heater is capable of accommodating a large amount of compressive or tensile strains in a completely reversible fashion, thereby yielding an excellent mechanical flexibility. The AgNW networks demonstrated here possess attractive features for both conventional and emerging applications of transparent flexible electrodes.
A scalable and facile method of preparing highly transparent and flexible electrodes for film heaters based on solution‐ processed silver‐nanowire (AgNW) networks is presented. By optimizing the network structure of AgNWs, highly transparent and conductive AgNW films are demonstrated, which can yield the effective and rapid heating of the film at low input voltages.
We report a high-performance supercapacitor incorporating a poly(ionic liquid)-modified reduced graphene oxide (PIL:RG-O) electrode and an ionic liquid (IL) electrolyte (specifically, ...1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide or EMIM-NTf2). PIL:RG-O provides enhanced compatibility with the IL electrolyte, thereby increasing the effective electrode surface area accessible to electrolyte ions. The supercapacitor assembled with PIL:RG-O electrode and EMIM-NTf2 electrolyte showed a stable electrochemical response up to 3.5 V operating voltage and was capable of yielding a maximum energy density of 6.5 W·h/kg with a power density of 2.4 kW/kg. These results demonstrate the potential of the PIL:RG-O material as an electrode in high-performance supercapacitors.
Human bone marrow-derived mesenchymal stem cells (hBMSCs) present promising opportunities for therapeutic medicine. Carbon derivatives showed only marginal enhancement in stem cell differentiation ...toward bone formation. Here we report that red-light absorbing carbon nitride (C3N4) sheets lead to remarkable proliferation and osteogenic differentiation by runt-related transcription factor 2 (Runx2) activation, a key transcription factor associated with osteoblast differentiation. Accordingly, highly effective hBMSCs-driven mice bone regeneration under red light is achieved (91% recovery after 4 weeks compared to 36% recovery in the standard control group in phosphate-buffered saline without red light). This fast bone regeneration is attributed to the deep penetration strength of red light into cellular membranes via tissue and the resulting efficient cell stimulation by enhanced photocurrent upon two-photon excitation of C3N4 sheets near cells. Given that the photoinduced charge transfer can increase cytosolic Ca2+ accumulation, this increase would promote nucleotide synthesis and cellular proliferation/differentiation. The cell stimulation enhances hBMSC differentiation toward bone formation, demonstrating the therapeutic potential of near-infrared two-photon absorption of C3N4 sheets in bone regeneration and fracture healing.
Large-scale integration of vanadium dioxide (VO2) on mechanically flexible substrates is critical to the realization of flexible smart window films that can respond to environmental temperatures to ...modulate light transmittance. Until now, the formation of highly crystalline and stoichiometric VO2 on flexible substrate has not been demonstrated due to the high-temperature condition for VO2 growth. Here, we demonstrate a VO2-based thermochromic film with unprecedented mechanical flexibility by employing graphene as a versatile platform for VO2. The graphene effectively functions as an atomically thin, flexible, yet robust support which enables the formation of stoichiometric VO2 crystals with temperature-driven phase transition characteristics. The graphene-supported VO2 was capable of being transferred to a plastic substrate, forming a new type of flexible thermochromic film. The flexible VO2 films were then integrated into the mock-up house, exhibiting its efficient operation to reduce the in-house temperature under infrared irradiation. These results provide important progress for the fabrication of flexible thermochromic films for energy-saving windows.
A practical route to the production of solution phase transferable graphene sheets using ionic liquid polymers (PIL) as a transferring medium is developed. Chemically converted graphene sheets ...decorated with PIL were found to be stable against the chemical reduction and well dispersed in the aqueous phase without any agglomeration. Upon the anion exchange of the PIL on graphene sheets, these PIL-modified graphene sheets in aqueous phase are readily transferred into the organic phase by changing their properties from hydrophilic to hydrophobic.
Down to the wire: A simple and effective method to synthesize silver nanowires through an ionic-liquid-assisted polyol process is developed (see scheme; scale bar=5 nm). The ionic liquids are tuned ...to provide the anisotropic growth of silver nanoparticles into nanowires.
The absence of effective therapeutics against Alzheimer's disease (AD) is a result of the limited understanding of its multifaceted aetiology. Because of the lack of chemical tools to identify ...pathological factors, investigations into AD pathogenesis have also been insubstantial. Here we report chemical regulators that demonstrate distinct specificity towards targets linked to AD pathology, including metals, amyloid-β (Aβ), metal-Aβ, reactive oxygen species, and free organic radicals. We obtained these chemical regulators through a rational structure-mechanism-based design strategy. We performed structural variations of small molecules for fine-tuning their electronic properties, such as ionization potentials and mechanistic pathways for reactivity towards different targets. We established in vitro and/or in vivo efficacies of the regulators for modulating their targets' reactivities, ameliorating toxicity, reducing amyloid pathology, and improving cognitive deficits. Our chemical tools show promise for deciphering AD pathogenesis and discovering effective drugs.
•Lithium intercalated graphite (LIG) with a thin passivation layer on the surface was produced.•A passivation layer consisting of Li2CO3 functions as preformed stable solid electrolyte interphase ...(SEI) film.•Lithium ion batteries with LIG shows a high reversible capacity, high Coulombic efficiency, and stable cycle life.
Graphite has been the most common anode materials in the Li-ion batteries (LIBs). However, it has a limited Coulombic efficiency and cycling stability which are crucial for the practical use of LIBs. Here, we present a lithium (Li)-intercalated graphite (LIG) electrode with a stable passivating layer on the surface for an improved electrochemical performance. The LIG was prepared by thermal treatment of commercial graphite in the presence of Li metal vapor and subsequent exposure to air. Characterization revealed that the surface of LIG was passivated by a thin inorganic compound (Li2CO3). This passivation layer on the graphite surface function as a preformed stable solid electrolyte interphase (SEI) films and allows the graphite electrode to deliver a high reversible capacity, high Coulombic efficiency, and stable cycle life.
High-quality silver (Ag) nanowires with specific dimensions were synthesized by a polyol method with detailed control of the synthesis conditions. For the same amount of AgNO3, the Ag nanowire ...density became higher as the nanowire diameter decreases and the length increases. This trend was replicated in Ag nanowire films coated on poly(ethylene terephthalate) films and higher densities of Ag nanowires and their junctions were observed in thinner and shorter nanowire networks. Nanowire films with a low sheet resistance (<100Ωsq−1) and a high transmittance (>90%) resulted from thin, long Ag nanowires. A modified percolation model, which emphasized the importance of the nanowire junction density, was in good agreement with the experimental observations. Meanwhile, long Ag nanowires were found to be undesirable in respect of their uniform coating over a large area. These results offer important design rules of Ag nanowires for highly conductive and transparent nanowire films.
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