92 research outputs found

    A class of multifunctional smart energy materials

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    Funding Information: S. Goswami would like to thank to Lisboa2020 Programme, Centro 2020 programme, Portugal 2020, European Union, through the European Social Fund who supported LISBOA-05-3559-FSE-000007 and CENTRO-04-3559-FSE-000094 operations as well as to Fundação para a Ciência e Tecnologia (FCT) and Agência Nacional de Inovação (ANI). Publisher Copyright: © 2022 The AuthorsPolymer material provides significant advantages over the conventional inorganic material-based electronics due to its attractive features including miniaturized dimension and feasible improvisations in physical properties through molecular design and chemical synthesis. In particular, conjugate polymers are of great interest because of their ability to control the energy gap and electronegativity through molecular design that has made possible the synthesis of conducting polymers with a range of ionization potentials and electron affinities. Polyaniline (PANI) is one of the most popular conjugated polymers that has been widely explored so far for its multifunctionality in diverse potential applications. This review is focusing on the recent advances of PANI for smart energy applications including supercapacitors, batteries, solar cells and nanogenerators and the development in its synthesis, design, and fabrication processes. A details investigation on the different types of chemical process has been discussed to fabricate PANI in nanostructures, film, and composites form. The paper includes several studies which are advantageous for understanding: the unique chemical and physical properties of this polymer; and the easily tunable electrical properties along with its redox behavior; and different processes to develop nanostructures, film, or bulk form of PANI that are useful to derive its applicability in smart objects or devices.publishersversionpublishe

    Investigation of Formation and Dissociation Mechanisms of Pure and Mixed CO2 Hydrates in the Presence of Thermodynamic and Kinetic Promoters using Molecular Dynamics Simulation

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    CO2 hydrates as non-flammable solid compounds would contribute to many industrial processes. Toward developing substantial applications of CO2 hydrates, molecular dynamics (MD) simulations can aid to understand their characteristics and mechanisms involved so that complete the laboratory experimental results at a macroscopic level. In this regard, understanding the promotion mechanisms of promoters on the hydrate formation and dissociation at the molecular level would assist in either establishing feasible processes or finding more efficient promoters

    Classical and reactive molecular dynamics: Principles and applications in combustion and energy systems

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    Molecular dynamics (MD) has evolved into a ubiquitous, versatile and powerful computational method for fundamental research in science branches such as biology, chemistry, biomedicine and physics over the past 60 years. Powered by rapidly advanced supercomputing technologies in recent decades, MD has entered the engineering domain as a first-principle predictive method for material properties, physicochemical processes, and even as a design tool. Such developments have far-reaching consequences, and are covered for the first time in the present paper, with a focus on MD for combustion and energy systems encompassing topics like gas/liquid/solid fuel oxidation, pyrolysis, catalytic combustion, heterogeneous combustion, electrochemistry, nanoparticle synthesis, heat transfer, phase change, and fluid mechanics. First, the theoretical framework of the MD methodology is described systemically, covering both classical and reactive MD. The emphasis is on the development of the reactive force field (ReaxFF) MD, which enables chemical reactions to be simulated within the MD framework, utilizing quantum chemistry calculations and/or experimental data for the force field training. Second, details of the numerical methods, boundary conditions, post-processing and computational costs of MD simulations are provided. This is followed by a critical review of selected applications of classical and reactive MD methods in combustion and energy systems. It is demonstrated that the ReaxFF MD has been successfully deployed to gain fundamental insights into pyrolysis and/or oxidation of gas/liquid/solid fuels, revealing detailed energy changes and chemical pathways. Moreover, the complex physico-chemical dynamic processes in catalytic reactions, soot formation, and flame synthesis of nanoparticles are made plainly visible from an atomistic perspective. Flow, heat transfer and phase change phenomena are also scrutinized by MD simulations. Unprecedented details of nanoscale processes such as droplet collision, fuel droplet evaporation, and CO2 capture and storage under subcritical and supercritical conditions are examined at the atomic level. Finally, the outlook for atomistic simulations of combustion and energy systems is discussed in the context of emerging computing platforms, machine learning and multiscale modelling

    Aqueous organic redox-flow-batteries: from electrolyte development to detailed stability studies

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    To reach the political aims of the Kyoto Protocol and the Paris Agreement, the energy production must change from fossil fuels to sustainable sources like water, sun, and wind. But the fluctuation output of these techniques must be compensated by a smart grid. Herein, the integration of large-scale energy storage systems is inevitable. The possibility to use cheap organic molecules in “green” and non-toxic electrolytes make the emerging technology of organic redox flow batteries a promising candidate for this mission. Nevertheless, this battery concept suffers from many problems. One of the major ones is the insufficient stability of the active materials. To overcome this technical teething trouble, a combination of material and sensor development to investigate and mitigate decomposition processes is required. But currently, the research is more focused on development of new redox-active molecules with intrinsically higher stabilities than on investigating, understanding, and improving the underlying processes. Beside some exceptions, most research groups concentrate on demonstrating stabilities by cycling the material as often as possible. In addition, the influence of the used SOC of the battery is mostly uninvestigated. A battery management system which might limit the used SOC could improve the device lifespan. Therefore, precise, fast, and cheap monitoring systems for SOC and SOH determination are needed. The commonly applied techniques suffer from major drawbacks, like expensive equipment, material limitations, temperature dependency, and the need for (re)calibrations to name only a few. A protocol that is capable of monitoring these parameters on the electrolyte level and not on the battery level could unlock a deeper understanding of the ongoing processes inside the device or electrolyte. Possible device lifespan improvements could then not only be addressed by the material itself but also by the cycling conditions or other external factors

    Feature Papers in Electronic Materials Section

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    This book entitled "Feature Papers in Electronic Materials Section" is a collection of selected papers recently published on the journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power- and high-frequency electronics, optoelectronic devices, detectors, etc.). In the first part of the book, many articles are dedicated to wide band gap semiconductors (e.g., SiC, GaN, Ga2O3, diamond), focusing on the current relevant materials and devices technology issues. The second part of the book is a miscellaneous of other electronics materials for various applications, including two-dimensional materials for optoelectronic and high-frequency devices. Finally, some recent advances in materials and flexible sensors for bioelectronics and medical applications are presented at the end of the book

    Flexographic printed nanogranular LBZA derived ZnO gas sensors: Synthesis, printing and processing

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    Within this document, investigations of the processes towards the production of a flexographic printed ZnO gas sensor for breath H2 analysis are presented. Initially, a hexamethylenetetramine (HMTA) based, microwave assisted, synthesis method of layered basic zinc acetate (LBZA) nanomaterials was investigated. Using the synthesised LBZA, a dropcast nanogranular ZnO gas sensor was produced. The testing of the sensor showed high sensitivity towards hydrogen with response (Resistanceair/ Resistancegas) to 200 ppm H2 at 328 °C of 7.27. The sensor is highly competitive with non-catalyst surface decorated sensors and sensitive enough to measure current H2 guideline thresholds for carbohydrate malabsorption (Positive test threshold: 20 ppm H2, Predicted response: 1.34). Secondly, a novel LBZA synthesis method was developed, replacing the HMTA by NaOH. This resulted in a large yield improvement, from a [OH-] conversion of 4.08 at% to 71.2 at%. The effects of [OH-]/[Zn2+] ratio, microwave exposure and transport to nucleation rate ratio on purity, length, aspect ratio and polydispersity were investigated in detail. Using classical nucleation theory, analysis of the basal layer charge symmetries, and oriented attachment theory, a dipole-oriented attachment reaction mechanism is presented. The mechanism is the first theory in literature capable of describing all observed morphological features along length scales. The importance of transport to nucleation rate ratio as the defining property that controls purity and polydispersity is then shown. Using the NaOH derived LBZA, a flexographic printing ink was developed, and proof-of-concept sensors printed. Gas sensing results showed a high response to 200 ppm H2 at 300 °C of 60.2. Through IV measurements and SEM analysis this was shown to be a result of transfer of silver between the electrode and the sensing layer during the printing process. Finally, Investigations into the intense pulsed light treatment of LBZA were conducted. The results show that dehydration at 150 °C prior to exposure is a requirement for successful calcination, producing ZnO quantum dots (QDs) in the process. SEM measurements show mean radii of 1.77-2.02 nm. The QDs show size confinement effects with the exciton blue shifting by 0.105 eV, and exceptionally low defect emission in photoluminescence spectra, indicative of high crystalline quality, and high conductivity. Due to the high crystalline quality and amenity to printing, the IPL ZnO QDs have numerous potential uses ranging from sensing to opto-electronic devices

    Catalysts for Sustainable Hydrogen Production: Preparation, Applications and Process Integration

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    In this book, we propose a collection of scientific and review articles on the production of hydrogen. The articles focus on the controlled storage and release of hydrogen; on the production of hydrogen from reforming from renewable sources, water splitting, and biological and photonic methods; on the intensification of the water gas shift process; and on the integration with purification methods such as pressure swing adsorption

    Study on the Mechanical Properties of Carbon Nanotube Coated‒Fiber Multi-Scale (CCFM) Hybrid Composites

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Photoluminescence Properties of Carbon Nanomaterials during Coronation and Biodegradation

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    Carbon nanomaterials (CNMs) have been widely used in biomedical applications such as drug delivery, biosensing, and bioimaging. Due to their interactions with the biological systems in these applications, it is important to understand what happens to CNMs in vivo. Upon introduction into a biological environment, CNMs are rapidly coated with biomolecules (90% lipids) resulting in so-called ‘biocorona’. CNMs can also undergo additional bio-transformations including partial or complete biodegradation. This dissertation focuses on using fluorescence spectroscopy to study the chemical reactions between CNMs and different biomolecules upon coronation and biodegradation. We first use fluorescence spectroscopy to study the reactions between the single-walled carbon nanotubes (SWCNTs) and the biologically important oxygenated lipid metabolites. A photoinduced cycloaddition reaction between metabolites bearing enone functional groups and SWCNTs is reported here. By creating covalent and tunable sp3 defects in the sp2 carbon lattice of SWCNTs through [2π + 2π] photocycloaddition, a bright red-shifted photoluminescence (PL) was gradually generated. The mechanism of the photocycloaddition reaction was further investigated by comparing the reactivity with various organic molecules and computational calculations. The results of this study can enable engineering of the optical and electronic properties of semiconducting SWCNTs and provide understanding into their interactions with the lipid biocorona. In addition to coronation, CNMs could induce a robust inflammatory response. Our research group has found that these effects can be mitigated by enzymatic biodegradation of CNMs through a peroxidase enzyme released by neutrophils during inflammation, myeloperoxidase (MPO). We performed PL studies on the MPO-catalyzed oxidation of graphene oxide (GO) and surfactant-coated SWCNTs. We further constructed two ratiometric sensors using SWCNT/GO nanoscrolls by incorporating surfactant-wrapped SWCNTs as the internal either turn-off or reference sensor. Our sensors show linear response to MPO oxidative machinery and hold the promise to be used as self-calibrating CNMs-based MPO activity indicators. Finally, the composition and structures of the fluorescent GO degradation products, in the form of polyaromatic hydrocarbons (PAHs), were analyzed using liquid chromatography–mass spectrometry and computational calculations. Our results indicated that structures with several conjugated benzene rings are likely to generate the observed PL
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