A strategy to optimize the performance of bio-derived carbon aerogels by a structuring additive

In this work, we investigated the influence of gum arabic (GA) as a structuring additive, on the electrochemical behavior of bio-derived carbon aerogels (CAGs). Modified carbonaceous materials were prepared by the gelatinization process of potato starch (PS) with the addition of GA in various quantities, followed by the thermal treatment of the obtained gels in an inert gas atmosphere. The obtained anode materials were examined by X-ray diffraction (XRD), elemental analysis (EA), galvanostatic charge/discharge tests (GCDT), extensive cycling (LT-GCDT) and cyclic voltammetry (CV) methods. The highest electrochemical performance was achieved for carbon aerogel material, in which 1% w/w GA was added. The results showed that the proper composition of carbon precursor with a structuring promoter improves the rheological properties of starch gel and stabilizes the final aerogel structure affecting CAG functional properties

Nitrogen-doped carbon aerogels derived from starch biomass with improved electrochemical properties for Li-ion batteries

Among all advanced anode materials, graphite is regarded as leading and still-unrivaled. However, in the modern world, graphite-based anodes cannot fully satisfy the customers because of its insufficient value of specific capacity. Other limitations are being nonrenewable, restricted natural graphite resources, or harsh conditions required for artificial graphite production. All things considered, many efforts have been made in the investigation of novel carbonaceous materials with desired properties produced from natural, renewable resources via facile, low-cost, and environmentally friendly methods. In this work, we obtained N-doped, starch-based carbon aerogels using melamine and N(2) pyrolysis as the source of nitrogen. The materials were characterized by X-ray powder diffraction, elemental analysis, X-ray photoelectron spectroscopy, galvanostatic charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. Depending on the doping method and the nitrogen amount, synthesized samples achieved different electrochemical behavior. N-doped, bioderived carbons exhibit far better electrochemical properties in comparison with pristine ones. Materials with the optimal amount of nitrogen (such as MCAGPS-N8.0%—carbon aerogel made from potato starch modified with melamine and CAGPS-N1.2%—carbon aerogel made from potato starch modified by N(2) pyrolysis) are also competitive to graphite, especially for high-performance battery applications. N-doping can enhance the efficiency of Li-ion cells mostly by inducing more defects in the carbon matrix, improving the binding ability of Li(+) and charge-transfer process

Electrochemical properties and structure evolution of starch-based carbon nanomaterials as Li-ion anodes with regard to thermal treatment

The influence of the pyrolysis temperature on the structural, textural, and electrochemical properties of carbon aerogels obtained from potato, maize, and rice starches was analyzed. The carbonization of organic precursors, followed by gelatinization, exchange of solvent, and drying process, was carried out in an argon atmosphere at temperatures ranging from 600 °C to 1600 °C. The nanostructured carbons were characterized by X-ray powder diffraction (XRD) as well as N2-adsorption/desorption (N2-BET) methods. The electrochemical behavior of Li-ion cells based on the fabricated carbon anodes was investigated using the galvanostatic charge/discharge tests (GCDT) and electrochemical impedance spectroscopy (EIS). The results show that the thermal treatment stage has a crucial impact on the proper formation of the aerogel material’s porous structures and also on their working parameters as anode materials. The highest relative development of the external surface was obtained for the samples pyrolysed at 700 °C, which exhibited the best electrochemical characteristics (the highest specific capacities as well as the lowest charge transfer resistances)

Design and synthesis of a new group of chiral complexes with PYRRBox ligands

W trakcie badań prezentowanych w niniejszej pracy zaprojektowano i zsyntezowano nowy, chiralny związek typu PYRRBox z podstawnikiem 2-tioksooksazolidynowym. Związek ten w postaci kompleksu z palladem(0) może być zastosowany jako katalizator asymetrycznej reakcji Hecka i reakcji Suzuki.During the research presented in this paper a new chiral PYRRBox typesubstituent with a 2-thioxooxazolidine group was designed and synthesized.Palladium(0) complex with this compound may be used as a catalyst inasymmetric Heck reactions and Suzuki reactions

Optimization of the CCL polymeric precursor synthesis

Głównym celem pracy była synteza polimerowych prekursorów przewodzących warstw węglowych, CCL. W pracy dokonano optymalizacji procesu polimeryzacji rodnikowej w roztworze N-winyloformamidu lub akrylamidu. Wyznaczono podstawowe wartości: stężeń, stosunków molowych inicjatora do monomeru, temperatury i czasu reakcji z uwzględnieniem dziesięciokrotnej zmiany skali. Badania dokumentowano pomiarami: lepkości syntezowanych polimerów (reometr obrotowy), średnich mas cząsteczkowych oraz wielkości polidyspersji (metoda chromatografii żelowej, SEC). Dla wszystkich otrzymanych poli(N-winyloformamidów) sporządzono kompozyty polimerów z modyfikatorami i wypełniaczami o strukturze oliwinu. Następnie po ich pirolizie i wytworzeniu warstw CCL zmierzono przewodnictwo. Dla wybranych materiałów skonstruowano ogniwa litowo-jonowe, które poddano testowaniu. Po wytypowaniu optymalnych parametrów syntezy oraz wytwarzania kompozytu, wykonano testy powtarzalności właściwości otrzymanych warstw CCL. Zaproponowano mechanizm oddziaływania modyfikatora z polimerem w roztworze.The main aim of this work was the synthesis of polymeric precursors of conductive carbon layers, CCL. The radical polymerization in a solution of N-vinylformamide and acrylamide was optimized. Basic values were determined: concentrations, molar ratios of initiator to monomer, the temperature and reaction time, including a tenfold increase in the scale of process. The studies were documented by measurements: the viscosity of the synthesized polymers (rotational rheometer), molar mass distribution and the polydispersity (by size-exclusion chromatography, SEC). For all the obtained poly (N-vinylformamide) solutions polymer composites with modifiers and olivine structure fillers were prepared. After pyrolysis and the production of CCL layers conductivity was measured. For selected materials lithium-ion cells were produced and tested. After the selection of optimal synthesis and the composite production parameters, tests of repeatability of CCL layers properties were performed. Mechanism of polymer interaction with the modifier in solution was proposed

Analysis of the Structure of Water Demand with the Example of Selected Buildings

The basis for the designing of water supply devices is knowledge of the distribution of water demand. The only practical tool that utility companies can use to measure water consumption is water meters. The literature part of the article compares the guidelines for the devices contained in the following directives: EEC (European Economic Community—withdrawn) and Measuring Instruments Directive—MID (applicable at present). The methodology of selecting water meters in accordance with previous and current regulations was also presented. The main purpose of this work was to determine the structure of water demand for selected building objects. Differences between real and literature values of water flows and water demand were determined. It was found that the average consumption in the analyzed buildings was higher then the consumption in Polish Regulation and in the town of Dabrowa Gornicza. The highest level of demand was in the buildings, which were equipped with automatic watering systems. The maximum momentary volumetric flows are also shown. Based on the obtained data, the accuracy of the water meters selection was checked. The calculated daily and hourly peak factors were compared with the values from the literature. The analysis was performed based on current legal acts, technical literature and data obtained from Dabrowskie Wodociagi Sp. z o.o. in Dabrowa Gornicza, Poland