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...

Titanium dioxide (TiO2) and zinc oxide (ZnO) nanostructures have been widely used as photo-catalysts due to their low-cost, high surface area, robustness, abundance and non-toxicity. In this work, four TiO2 and ZnO-based nanostructures, i.e. TiO2 nanoparticles (TiO2 NPs), TiO2 nanotubes (TiO2 NTs), ZnO nanowires (ZnO NWs) and ZnO@TiO2 core-shell structures, specifically prepared with a fixed thickness of about 1.5 μm, are compared for the solar-driven water splitting reaction, under AM1.5G simulated sunlight. Complete characterization of these photo-electrodes in their structural and photo-electrochemical properties was carried out. Both TiO2 NPs and NTs showed photo-current saturation reaching 0.02 and 0.12 mA cm(-2), respectively, for potential values of about 0.3 and 0.6 V vs. RHE. In contrast, the ZnO NWs and the ZnO@TiO2 core-shell samples evidence a linear increase of the photocurrent with the applied potential, reaching 0.45 and 0.63 mA cm(-2) at 1.7 V vs. RHE, respectively. However, under concentrated light conditions, the TiO2 NTs demonstrate a higher increase of the performance with respect to the ZnO@TiO2 core-shells. Such material-dependent behaviours are discussed in relation with the different charge transport mechanisms and interfacial reaction kinetics, which were investigated through electrochemical impedance spectroscopy. The role of key parameters such as electronic properties, specific surface area and photo-catalytic activity in the performance of these materials is discussed. Moreover, proper optimization strategies are analysed in view of increasing the efficiency of the best performing TiO2 and ZnO-based nanostructures, toward their practical application in a solar water splitting device.

The air permeability of PDMS membranes is easily tuned acting on their composition. Varying the mixing ratio it is possible to strongly influence the gas molecules permeation across the PDMS membrane.

In certain polymers the graphenization of carbon atoms can be obtained by laser writing owing to the easy absorption of long-wavelength radiation, which generates photo-thermal effects. On a polyimide surface this process allows the formation of a nanostructured and porous carbon network known as laser-induced graphene (LIG). Herein we report on the effect of the process parameters on the morphology and physical properties of LIG nanostructures. We show that the scan speed and the frequency of the incident radiation affect the gas evolution, inducing different structure rearrangements, an interesting nitrogen self-doping phenomenon and consequently different conduction properties. The materials were characterized by infrared and Raman spectroscopy, XPS elemental analysis, electron microscopy and electrical/electrochemical measurements. In particular the samples were tested as interdigitated electrodes into electrochemical supercapacitors and the optimized LIG arrangement was tested in parallel and series supercapacitor configurations to allow power exploitation.

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Laser-induced graphene (LIG) emerged as one of the most promising materials for flexible functional devices. However, the attempts to obtain LIG onto elastomeric substrates never succeed, hindering its full exploitation for stretchable electronics. Herein, a novel polymeric composite is reported as a starting material for the fabrication of graphene-based electrodes by direct laser writing. A polyimide (PI) powder is dispersed into the poly­(dimethylsiloxane) (PDMS) matrix to achieve an easily processable and functional elastomeric substrate, allowing the conversion of the polymeric surface into laser-induced graphene (LIG). The mechanical and electrical properties of the proposed material can be easily tuned by acting on the polyimide powder concentration. The reported procedure takes advantage from the simple casting process, typical of silicone elastomer, allowing to produce electrodes conformable to any kind of shape and surface as well as complex three-dimensional structures. Electrochemical capacitors and strain gauges are selected as flexible prototypes to demonstrate the multifunctional properties of the obtained LIG on the PDMS/PI composite substrate.

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