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Nickel-catalyzed reductive 1,4-alkylarylation of 1,3-enynes to access tetra-substituted allenes
No full textSustainable charged composites with amphiphobic surfaces for harsh environment-tolerant non-contact mode triboelectric nanogenerators
No full textIn this work, the sustainable charged composites with amphiphobic surfaces are reported regarding harsh environment tolerance and robust contactless mode triboelectric nanogenerators (TENGs). SiO2 and polytetrafluoroethylene (PTFE) particles are well dispersed in thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS), respectively. Both surfaces become very rough after a chemical etching method and the surface of PTFE-PDMS is fluorinated using a fluorinated alkylsilane, resulted in the formation of amphiphobic surfaces. This significantly enhances the environment tolerance of the contactless mode TENGs as well as the charge retention characteristics of the composites. As a practical non-contact mode application, a speed sensor fabricated using two composites can stably detect a low vehicle speed less than 3.75 km/h when exposed to high humidity (similar to 99%) and various chemical oils. Over 50% of initial output voltage are still generated after 2 weeks with no more decrease after 5 days, showing a 1.4 times slower charge decay rate, compared with the reference Ni-PTFE based TENG
Synergetic Effect of the Iridium Complex for Morphology Optimization in Efficient and Thermally Stable Polymer Solar Cells
No full textActive layer morphology is one of the crucial factors for achieving excellent device performance in polymer solar cells. Recently, solid additives have drawn great attention due to their great potential in morphology control, but a detailed explanation about the working mechanism of solid additive systems is still lacking. In this work, we provided an iridium complex-based solid additive (Ir-OH) to control the morphology and crystallinity of the photoactive layer by utilizing the synergetic effect of dual additives 1-chloronaphthalene and Ir-OH. The morphology of the devices with dual additives exhibited appropriate phase separation and domain size, which provided more continuous pathways for charge transport and also exhibited condensed pi-pi stacking and fine molecular ordering of photoactive materials, resulting in enhanced charge collection probability. Consequently, the treatment of dual additives exhibited enhanced power conversion efficiency (PCE) with enhanced exciton dissociation, charge collection, and reduced bimolecular recombination. In addition, we found that the device with dual additives exhibited strong thermal stability under a constant heat treatment at 130 degrees C, and the device performance retained 65% during 24 h, showing an improved PCE of 13.89%. We expected that the favorable morphology of active materials in metal complexes can suppress thermal degradation and lead to improved device performance
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No full textTOUCH SCREEN PANNEL AND DRIVING METHOD OF THE SAME
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Wafer-Scale Memristor Array Based on Aligned Grain Boundaries of 2D Molybdenum Ditelluride for Application to Artificial Synapses
No full text2D materials have attracted attention in the field of neuromorphic computing applications, demonstrating the potential for their use in low-power synaptic devices at the atomic scale. However, synthetic 2D materials contain randomly distributed intrinsic defects and exhibit a stochasitc forming process, which results in variability of switching voltages, times, and stat resistances, as well as poor synaptic plasticity. Here, this work reports the wafer-scale synthesis of highly polycrystalline semiconducting 2H-phase molybdenum ditelluride (2H-MoTe2) and its use for fabricating crossbar arrays of memristors. The 2H-MoTe2 films contain small grains (approximate to 30 nm) separated by vertically aligned grain boundaries (GBs). These aligned GBs provide confined diffusion paths for metal ions filtration (from the electrodes), resulting in reliable resistive switching (RS) due to conductive filament confinement. As a result, the polycrystalline 2H-MoTe2 memristors shows improvement in the RS uniformity and stable multilevel resistance states, small cycle-to-cycle variation (<8.3%), high yield (>83.7%), and long retention times (>10(4) s). Finally, 2H-MoTe2 memristors show linear analog synaptic plasticity under more than 2500 repeatable pulses and a simulation-based learning accuracy of 96.05% for image classification, which is the first analog synapse behavior reported for 2D MoTe2 based memristors
Low-Palladium-Content Iron(III) Nanocatalyst Supported on Zeolite-NaY for C-Cl Bond Activation
No full textA heterogeneous nanocatalyst comprising palladium (Pd/PdO) and iron(III) oxide (Fe2O3) in the dimension of 1-4 nm was synthesized using sodium-exchanged zeolite-Y or zeolite-NaY [a type of faujasite (FAU) zeolite having an aluminosilicate framework with a general formula of (Na-2)(3).5[Al7Si17O48].32H(2)O] as a support matrix. The catalyst was investigated as a true heterogeneous catalyst for activation of the robust C-Cl bond of aryl chlorides in the Suzuki-Miyaura cross-coupling (SMCC) reaction. The catalyst with very low Pd loading (0.0037 mol %) exhibited high reactivity in the SMCC reaction with various derivatives of aryl chlorides (Ar-Cl). Biaryl products were obtained with up to a 92% yield, high selectivity, and a good turnover number with this Pd/PdO-Fe2O3-Y catalyst. The catalyst exhibited good thermal stability and was highly recyclable. The reaction was found to be reliant on various parameters such as solvent system, temperature, time, and catalyst amount. A small aliquot of water (H2O) mixed with methanol (CH3OH) dramatically brought a substantial improvement in the product yield of the desired biaryl product. The role of zeolite-NaY was also investigated by comparing the results with various other synthesized catalysts. Different experimental studies indicated that the surface hydroxyl (-OH) groups of zeolite-NaY, modification of basic sites, and the ability to influence the reduction temperature of iron (Fe) and palladium (Pd) influenced the catalytic performance of the synthesized catalyst. The impact of Fe on the electronic structure and reactivity of Pd was analyzed through a density functional theory calculation. This study provided strong evidence for creation of a negative (-ve) charge on Pd with an increasing amount of Fe content and thereby favored the in situ transformation of Pd(II) to Pd(0) as required in the activation of the C-Cl bond
Development of Test-bed System for LVDC Grid Connected to Multiple Converters Using PHIL Simulation
No full textIn this paper, a power hardware-in-the-loop (PHIL)-simulation-based test-bed was proposed to verify the stability and reliability of a low-voltage direct current (LVDC) grid comprising multiple converters. The test-bed comprised a source converter and a load converter with constant power load characteristics. The impedance interaction between the source and load converters was analyzed using the extra element theorem to assess the stability of the LVDC grid. Moreover, considering the non-ideal elements of the PHIL simulation system, an accurate PHIL simulation was performed to validate the stability of the LVDC grid comprising multiple converters. The effectiveness of the proposed PHIL simulation test-bed was demonstrated using a real-time simulator, an Opal-RT OP5700, a power interface, and a 0.5 kW dual-active-bridge converter. The validity of the test-bed was also verified by experiments and analysis using stability criteria
Design Strategies of Active and Stable Oxygen Evolution Catalysts for Proton Exchange Membrane Water Electrolysis
No full textProton exchange membrane water electrolyzers (PEMWEs) hold great promise for the efficient production of clean hydrogen, which is vital for the transition of the current hydrocarbon-based energy infrastructure to a sustainable, circular energy future. The efficiency of a PEMWE relies heavily on the performance of the oxygen evolution reaction (OER) at the anode. Accordingly, the development of highly active and stable OER catalysts under acidic conditions is crucial for the practical implementation of PEMWEs. Herein, we present recent advances in efficient acidic OER catalysts, focusing on their rational design and in situ characterization. We illustrate representative synthetic strategies that can boost the intrinsic activity, extrinsic activity, and stability of acidic OER catalysts. Next, we discuss state-of-the-art in situ characterization techniques that enable the identification of active catalytic sites and an understanding of the OER pathways. Finally, we summarize the OER activities of high-performance catalysts in half- and single-cell configurations, providing meaningful insights into bridging the gap between the laboratory-scale development of a new catalyst and its device-level implementation for PEMWEs
