Thermal Conductivity Performance of 2D hBN/MoS 2/Hybrid Nanostructures Used on Natural and Synthetic Esters

In this paper, the thermal conductivity behavior of synthetic and natural esters reinforced with 2D nanostructures-single hexagonal boron nitride (h-BN), single molybdenum disulfide (MoS2), and hybrid h-BN/MOS2-were studied and compared to each other. As a basis for the synthesis of nanofluids, three biodegradable insulating lubricants were used: FR3TM and VG-100 were used as natural esters and MIDEL 7131 as a synthetic ester. Two-dimensional nanosheets of h-BN, MoS2, and their hybrid nanofillers (50/50 ratio percent) were incorporated into matrix lubricants without surfactants or additives. Nanofluids were prepared at 0.01, 0.05, 0.10, 0.15, and 0.25 weight percent of filler fraction. The experimental results revealed improvements in thermal conductivity in the range of 20-32% at 323 K with the addition of 2D nanostructures, and a synergistic behavior was observed for the hybrid h-BN/MoS2 nanostructures

Micro Scalable Graphene Oxide Productions Using Controlled Parameters in Bench Reactor

The detailed study of graphene oxide (GO) synthesis by changing the graphite/oxidizing reagents mass ratios (mG/mROxi), provided GO nanosheets production with good yield, structural quality, and process savings. Three initial samples containing different amounts of graphite (3.0 g, 4.5 g, and 6.0 g) were produced using a bench reactor under strictly controlled conditions to guarantee the process reproducibility. The produced samples were analyzed by Raman spectroscopy, atomic force microscopy (AFM), x-ray diffraction (XDR), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetry (TGA) techniques. The results showed that the major GO product comprised of nanosheets containing between 1–5 layers, with lateral size up to 1.8 µm. Therefore, it was possible to produce different batches of graphene oxide with desirable physicochemical characteristics, keeping the amount of oxidizing reagent unchanged. The use of different proportions (mG/mROxi) is an important strategy that provides to produce GO nanostructures with high structural quality and scale-up, which can be well adapted in medium-sized bench reactor

Novo nanocompósito ternário baseado em politiofeno, óxido de grafeno reduzido e dióxido de manganês para armazenamento de energia

Os supercapacitores estão presentes em praticamente todo tipo de dispositivos eletrônicos que utilizamos no nosso dia-a-dia. Aplicações em sistemas para armazenamento da energia gerada a partir de fontes limpas e para a alimentação de automóveis elétricos, computadores e dos novos microdispositivos autossuficientes, requerem, no entanto, uma nova geração de materiais capacitivos. É necessário desenvolver supercapacitores com maior densidade capacitiva, melhor razão de capacidade e que mantenham a capacitância ao longo de vários ciclos. Para resolver este problema uma nova abordagem tem se mostrado promissora: a combinação de materiais de diferentes mecanismos capacitivos em compósitos ternários. A partir desta estratégia, tem se observado que a sinergia de três materiais leva a propriedades capacitivas superiores. Sendo assim, neste trabalho será apresentado um nanocompósito ternário inédito baseado em politiofeno, óxido de grafeno reduzido e dióxido de manganês. Tanto os componentes quanto o nanocompósito foram obtidos por rotas químicas simples, econômicas e eficientes. Adaptações no método de obtenção do óxido de grafeno reduzido resultaram num material de qualidade superior. O dióxido de manganês foi sintetizado por uma rota inovadora que apresenta vantagens em relação às mais utilizadas. Ao final, a sinergia dos três componentes conferiu ao nanocompósito propriedades de armazenamento de energia singulares e melhoradas em comparação com o politiofeno puro: a capacitância foi 230% maior que a do polímero com maior estabilidade cíclica nos 100 primeiros ciclos de carga e descarga.Supercapacitors are present in almost all kinds of electronic devices that we use in our everyday lives. Applications in systems for storing energy generated from clean sources and for powering electric cars, computers and the new self-sufficient microdevices, require, however, a new generation of capacitive materials. It is necessary to develop supercapacitors with higher capacitive density, better rate capability and that maintain the capacitance over several cycles. To address this problem, a novel approach has shown to be promising: the combination of materials of different capacitive mechanisms in ternary composites. From this strategy, it has been observed that the synergy of three materials leads to higher capacitive properties. Thus, in this work will be presented a novel ternary nanocomposite based on polythiophene, reduced graphene oxide and manganese dioxide. Both the components and the nanocomposite were obtained through simple, economical and efficient chemical routes. Adaptations in the method of obtaining the reduced graphene oxide resulted in a higher quality material. Manganese dioxide has been synthesized by an innovative route that presents advantages over the most used ones. At the end, the synergy of the three components led to singular and enhanced properties of energy storage in the nanocomposite compared to the pure polythiophene: the capacitance was 230% higher than that of the polymer with improved cyclic stability in the first 100 cycles of charge and discharge