Herein, we are reporting a rapid one-pot synthesis of MoS2-decorated laser-induced graphene (MoS2-LIG) by direct writing of polyimide foils. By covering the polymer surface with a layer of MoS2 dispersion before processing, it is possible to obtain an in situ decoration of a porous graphene network during laser writing. The resulting material is a three-dimensional arrangement of agglomerated and wrinkled graphene flakes decorated by MoS2 nanosheets with good electrical properties and high surface area, suitable to be employed as electrodes for supercapacitors, enabling both electric double-layer and pseudo-capacitance behaviors. A deep investigation of the material properties has been performed to understand the chemical and physical characteristics of the hybrid MoS2-graphene-like material. Symmetric supercapacitors have been assembled in planar configuration exploiting the polymeric electrolyte; the resulting performances of the here-proposed material allow the prediction of the enormous potentialities of these flexible energy-storage devices for industrial-scale production.
(polyimide and polyetherimide) [ 20 ] that cannot provide the suitable mechanical properties required for stretchable energystorage devices.Herein we report a simple method to transfer the LIG porous layer obtained onto polyimide sheet to a transparent and elastomeric substrate such as PDMS (polydimethylsiloxane). Morphology and chemical-physical properties of the obtained material were deeply characterized by electron microscopy investigation, contact angle measurements and vibrational spectroscopy analysis. The as-fabricated electrodes were assembled into symmetric electrical double-layer supercapacitors and, thanks to the intrinsic mechanical properties of PDMS, the retention of energy-storage performance under bending and stretching conditions was demonstrated.The fabrication process of the LIG/PDMS electrodes is described in the experimental section (see also Supporting Information) and schematically represented in Figure 1 a-d: porous LIG pattern was obtained by a direct writing of polyimide sheet using a nanosecond CO 2 laser (a); afterward the PDMS was poured onto the written sample and the air was evacuated by a vacuum step in order to allow the full infi ltration of PDMS into the 3D network (b); after a thermal curing at 80 °C for 1 h the LIG/PDMS slide was manually peeled off from the polyimide sheet (c,d). The resulting composite material take advantage of the unique mechanical properties typical of elastomers (Figure 1 e) and of the good electrical conductivity and high surface area intrinsically present in LIG structures. Figure 1 f,g show the transparency of a logo pattern written on polyimide foil and then transferred onto PDMS slice respectively. The preservation of the electric conduction was tested by using LIG/PDMS composite to close a circuit (powering a green LED) as shown in Figure 1 h and by electrical measurements. Current-voltage characteristics shown in Figure S1 (Supporting Information) were recorded on the LIG/PDMS sample subjected to stretching in the range 0%-50%, confi rming the good maintenance of electrical properties.FESEM characterization was used to assess the morphology of the LIG sample before and after transfer onto PDMS substrate. Figure 2 a,b show the characteristic 3D foam-like structure of the laser-written LIG sample, which is composed of multilayer graphene walls. The holey foam-like structure, which is a result of the emission of gases during the irradiation process, [ 20,21 ] is actually well suited for both infi ltration with PDMS and impregnation with the electrolyte for supercapacitor application. Figure 2 c presents a cross-sectional view of a LIG sample after it is successfully transferred onto a PDMS substrate through the cast-and-peel process. Thanks to the effective infi ltration of PDMS, the LIG shows good adhesion to the underlying fl exible substrate. Moreover, as shown in Figure 2 d-f, a 3D structure of interconnected multilayer The fi eld of wearable electronics has been evolving very rapidly in the last few years due to the increasing demand for fl exi...
Direct C-H bond activation is an important reaction in synthetic organic chemistry. This methodology has the potential to simplify reactions by avoiding the use of prefunctionalized reagents. However, selectivity, especially site selectivity, remains challenging. Sequential reactions, in which different molecules or groups are combined in an ordered sequence, represent a powerful tool for the construction of complex molecules in a single operation. We have discovered and developed a synthetic methodology that combines selective C-H bond activation with sequential reactions. This procedure, which is now known as the "Catellani reaction", enables the selective functionalization of both the ortho and ipso positions of aryl halides. The desired molecules are obtained with high selectivity from a pool of simple precursors. These molecules are assembled under the control of a palladacycle, which is formed through the joint action of a metal (Pd) and an olefin such as norbornene. These two species act cooperatively with an aryl halide to construct the palladacycle, which is formed through ortho-C-H activation of the original aryl halide. The resulting complex acts as a scaffold to direct the reaction (via Pd(IV)) of other species, such as alkyl or aryl halides and amination or acylation agents, toward the sp(2) C-Pd bond. At the end of this process, because of steric hindrance, the scaffold is dismantled by norbornene extrusion. Pd(0) is cleaved from the organic product through C-C, C-H, C-N, C-O, or C-B coupling, in agreement with the well-known reactivity of aryl-Pd complexes. The cycle involves Pd(0), Pd(II), and Pd(IV) species. In particular, our discovery relates to alkylation and arylation reactions. Recently, remarkable progress has been made in the following areas: (a) the installation of an amino or an acyl group at the ortho position of aryl halides, (b) the formation of a C-B bond at the ipso position, (c) the achievement of meta-C-H bond activation of aryl rings bearing a chelating directing group by Pd(II)/Pd(IV)/norbornene catalysis, and (d) the activation of N-H and C-H bonds in sequence for indole 2-alkylation. In this Account, we explain the main features of this methodology, describe its synthetic potential, and illustrate some remarkable progress that has been made, emphasizing the most recent developments and applications in total synthesis.
A three-electrode hybrid molecular electronic element based on polyaniline ͑PANI͒ emeraldine base-polyethylene oxide/LiCl was fabricated and tested. Source and drain electrodes were connected to the conducting polymer layer. Solid electrolyte was deposited as a narrow stripe over the PANI film, and the third electrode ͑gate͒, maintained at ground potential, was attached to it. Drain and gate currents were measured during a drain voltage sweep. Drain voltage-current characteristics revealed a rectifying behavior, while gate characteristics were similar to those for cyclic voltammograms. Such behavior was attributed to the electrochemical control of the redox state ͑and hence of conductivity͒ of PANI area under the solid electrolyte. The device was stable and reproducible with robust electrical characteristics. In particular, an asymmetry in time relaxation due to ion diffusion was found; a possible application of this to the use of this device in adaptive conducting networks is proposed.
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