Electrospinning as a route to advanced carbon fibre materials for selected low-temperature electrochemical devices: a review

Electrospinning has been proven as a highly versatile fabrication method for producing nano-structured fibres with controllable morphology, of both the fibres themselves and the void structure of the mats. Additionally, it is possible to use heteroatom doped polymers or to include catalytic precursors in the electrospinning solution to control the surface properties of the fibres. These factors make it an ideal method for the production of electrodes and flow media for a variety of electrochemical devices, enabling reduction in mass transport and activation overpotentials and therefore increasing efficiency. Moreover, the use of biomass as a polymer source has recently gained attention for the ability to embed sustainable principles in the materials of electrochemical devices, complementing their ability to allow an increase in the use of renewable electricity via their application. In this review, the historical and recent developments of electrospun materials for application in redox flow batteries, fuel cells, metal air batteries and supercapacitors are thoroughly reviewed, including an overview of the electrospinning process and a guide to best practice. Finally, we provide an outlook for the emerging use of this process in the field of electrochemical energy devices with the hope that the combination of tailored microstructure, surface functionality and computer modelling will herald a new era of bespoke functional materials that can significantly improve the performance of the devices in which they are used

Το Φαινόμενο της Αραβικής Άνοιξης Η κρίση της Συρίας και η στάση της Ευρωπαϊκής Ένωσης

Η παρούσα εργασία μελετά το φαινόμενο της Αραβικής Άνοιξης στην περιοχή της Συρίας και την εξέλιξή του σε μακροχρόνιο πόλεμο. Παρουσιάζεται η πολιτική και η στρατηγική που ακολούθησε η Ένωση καθόλη την διάρκεια του πολέμου στην περιοχή. Τέλος γίνεται μία σύντομη αναφορά στις δύο απο τις σημαντικότερες συνέπειες της Συριακής κρίσης στην Ευρωπαϊκή Ένωση την Τροκροτία και την Μετανάστευση.This paper studies the phenomenon of the Arab Spring in the region of Syria and its evolution into a long war. The policy and strategy followed by the Union throughout the war in the region are presented. To sum up, I am talking about two of the most important consequences of the Syrian crisis in the European Union, the Tropocracy and Immigration

Isolation and molecular characterisation of malathion-degrading bacterial strains from waste water in Egypt

Efficiencies of local bacterial isolates in malathion degradation were investigated. Five bacterial isolates obtained from agricultural waste water were selected due to their ability to grow in minimal salt media, supplied with 250 ppm malathion as sole source of carbon and phosphorus. The purified bacterial isolates (MOS-1, MOS-2, MOS-3, MOS-4 and MOS-5) were characterised and identified using a combination of cellular profile (SDS-PAGE), genetic make up profile (RAPD-PCR), and morphological and biochemical characteristics. Four bacterial isolates (MOS-1, MOS-2, MOS-3 and MOS-4) with identical genetic characteristics were identified as Enterobacter aerogenes, whereas isolate MOS-5 was identified as Bacillus thuringiensis. The degradation rate of malathion in liquid culture was estimated during 15 days of incubation for the isolate MOS-5 of B. thuringiensis. Slightly more than 50% of the initial malathion was decomposed within 3 days. The malathion concentration decreased to almost 17% in the inoculated medium after 10 days incubation, while more than 91% of the initial malathion was degraded after 15 days

A Promising N doped Carbon Metal Oxide Hybrid Electrocatalyst Derived from Crustacean s Shells Oxygen Reduction and Oxygen Evolution

The development of both efficient and durable Pt free catalysts for oxygen reduction ORR is extremely important to realize the world wide commercialization of clean energy technologies, such as fuel cells and batteries, which is currently hindered by the exorbitant cost and scarcity of the state of the art Pt based catalysts. As a potential alternative to such expensive catalysts, this investigation addresses the facile synthesis of an efficient, durable and highly poison tolerant metal free N doped carbon Nd2O3 hybrid bifunctional electrocatalyst for ORR and water splitting, which has been derived from encapsulated Nd OH 3 in the chitosan matrix N C Nd2O3 . Chitosan, obtained from the crustacean s shells, assists to form a smaller Nd2O3 particle sizes and at the same time yields an efficiently nitrogen doped graphitic structure with outstanding activity and durability for ORR in alkaline and acidic media. N C Nd2O3 catalyst exhibits 50 mV positive shift in half wave potential with a comparable onset potential and limiting current density of ORR to that of Pt C catalyst with same loading in 0.1 M KOH. Additionally, N C Nd2O3 shows a high tolerance towards crossover of the various anodic fuels concurrent with outstanding tolerance against poisoning with various hydrocarbon impurities e.g., acetonitrile, acrylonitrile, etc in situ generated during fuel cell operation. N C Nd2O3 activity shows only a slight attenuation of 3 after 8 h of continuous ORR and 6 in the presence of 50 ppm of acetonitrile compared with 50 and 80 observed at Pt C. In a H2 air single cell a membrane electrode assembly MEA prepared from N C Nd2O3 as a cathode catalyst delivered a maximum power density of 287 mW cm2 and current density of 572 mA cm 2 at 0.6 V which is especially outstanding. The superior electrocatalytic activity and durability of the as prepared catalysts mainly originate from the synergistic effects between Nd2O3 particles and chitosan functional groups, besides the nitrogen doped nature of the as prepared catalyst. Furthermore, the as prepared catalyst shows a high activity and durability in the oxygen evolution reaction OER as well, making it an efficient non precious bifunctional catalyst. The facile preparation method with metal oxide encapsulated N doped graphitic structures from cheap, nature and ecofriendly chitosan opens up a new horizon for the world wide commercialization of fuel cells and metal air batterie

Degradation Phenomena of Bismuth-Modified Felt Electrodes in VRFB Studied by Electrochemical Impedance Spectroscopy

The performance of all-V redox flow batteries (VRFB) will decrease when they are exposed to dynamic electrochemical cycling, but also when they are in prolonged contact with the acidic electrolyte. These phenomena are especially severe at the negative side, where the parasitic hydrogen evolution reaction (HER) will be increasingly favored over the reduction of V(III) with ongoing degradation of the carbon felt electrode. Bismuth, either added to the electrolyte or deposited onto the felt, has been reported to suppress the HER and therefore to enhance the kinetics of the V(II)/V(III) redox reaction. This study is the first to investigate degradation effects on bismuth-modified electrodes in the negative half-cell of a VRFB. By means of a simple impregnation method, a commercially available carbon felt was decorated with Bi 2 O 3 , which is supposedly present as Bi(0) under the working conditions at the negative side. Modified and unmodified felts were characterized electrochemically using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a three-electrode setup. Surface morphology of the electrodes and composition of the negative half-cell electrolyte were probed using scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (TXRF), respectively. This was done before and after the electrodes were subjected to 50 charge-discharge cycles in a battery test bench. Our results suggest that not only the bismuth catalyst is dissolved from the electrode during battery operation, but also that the presence of bismuth in the system has a strong accelerating effect on electrode degradation

Biomass Fatty Acid Profile and Fuel Property Prediction of Bagasse Waste Grown <i>Nannochloropsis oculata</i>

The Chrythophyta alga Nannochloropsis oculata was mixotrophically grown in artificial media enriched with acid-prehydrolyzed bagasse waste as a source of organic carbon. The used growth medium was composed of F2 nutrients, sea salt (22.0 g L−1), and bagasse extract dissolved in sterile tap water. All of the determined growth parameters resulted in their maximums, as the alga was fed with 25% F2 growth medium enriched with 10% bagasse extract, while bagasse-extract-free medium engaged the total chlorophyll and carotenes at the expense of dry weight accumulation during the vegetative growth period. On the contrary, the dry weight under induction growth slightly differed among the different employed treatments; however, all the treatments surpassed the control one, and variation was obviously found in the cases of chlorophyll and carotene. A slight increase in oil content (6.19–11.89%) was observed, as the vegetative cells were grown under induction conditions. The fatty acids ranged between C16 and C20, and the proportions of SFA and MUFA increased from a sum of 63.57% to 88.31%, while the PUFA, including linoleic acid, α-linolenic acid, and arachidonic acid, declined from 36.3 to 11.69%. Concerning the fuel properties, the induction-produced oil surpassed the vegetative one