169,977 research outputs found
Supercapacitive operational mode in microbial fuel cell
No full textSupercapacitive microbial fuel cells (SC-MFCs) are an emerging and promising field that has captured the attention of scientists in the past few years. This hybridization consists in the integration of supercapacitive features in the MFC electrodes to boost the performance output. The MFC anaerobic and aerobic enviroments induce self-polarization of the electrodes. The electrodes can be discharged galvanostatically and then self-recharged by the biotic/abiotic environments. During the discharge, two main phenomena named electrostatic and faradaic take place but the separation and quantification of the two contributes seems to be challenging. Galvanostatic discharges of SC-MFC produce at least one order of magnitude higher current/power compared with continuous operations, making it promising for pulsed type applications.</p
Increased performance of electrodeposited PtRu/C-Nafion catalysts for DMFC
No full textPtRu catalysts were prepared by electrochemical deposition on C-Nafion supports sprayed on stainless steel current collectors. The effect of the electrochemically accessible surface area of the C-Nafion supports, of the Pt to C and Pt to Nafion mass ratio and of the electrodeposition conditions on catalytic activity of the PtRu/C-Nafion catalysts for methanol oxidation in direct methanol fuel cells (DMFC) was investigated. Our results demonstrate that optimized PtRu/C-Nafion catalysts display catalytic activity significantly higher than that of a commercial system tested in the same conditions
An electrochemical study of natural and chemically controlled eumelanin
No full textEumelanin is the most common form of the pigment melanin in the human body, with functions including antioxidant behavior, metal chelation, and free radical scavenging. This biopigment is of interest for biologically derived batteries and supercapacitors. In this work, we characterized the voltammetric properties of chemically controlled eumelanins produced from 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) building blocks, namely, DHI-melanin, DHICA-melanin, and natural eumelanin, extracted from the ink sac of cuttlefish, Sepia melanin. Eumelanin electrodes were studied for their cyclic voltammetric properties in acidic buffers including Na+, K+, NH4+, and Cu2+ ions. (C) 2017 Author(s)
I veicoli elettrici per un trasporto ad alto rendimento energetico e a basso impatto ambientale
No full textIl Piano Energetico Nazionale non può che prevedere per una mobilità sostenibile l’introduzione di veicoli elettrici ad alto rendimento energetico e a basso o nullo impatto ambientale. I veicoli elettrici alimentati con batterie convenzionali, in produzione presso le maggiori case automobilistiche, rappresentano già una soluzione per il traffico urbano Italiano, connotato da utenti con percorrenze giornaliere significativamente inferiori ai 100 km alla velocità massima di 50 km/h e quindi compatibili con le autonomie delle batterie. I veicoli alimentati con le più avanzate batterie al litio e con celle a combustibile, già sviluppati a livello prototipale, rappresentano, rispettivamente, le soluzioni a medio e a lungo termine per un traffico extraurbano. Nelle sezioni che seguono vengono descritte le problematiche che hanno sino ad oggi ritardato la conversione, anche solo parziale, dell’attuale parco macchine in elettrico e vengono messe in luce le direzioni da perseguire per una fattiva diffusione del veicolo elettrico
A novel galvanostatic polymerization for high specific capacitance poly(3-methylthiophene) in ionic liquid
No full textFor the first time it is here reported a novel and clean galvanostatic procedure to polymerize poly(3-methylthiophene) in the 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) ionic liquid (IL). The strategy consists in the use of the acid additive trifluoromethanesulfonimide (HTFSI) displaying the same anion of the IL and which provides an acid proton that is reduced to H2 at the counter electrode upon the anodic polymer growth on the working electrode and prevents consumption of the ionic liquid with great advantage in terms of costs. This procedure provides a pMeT electrode featuring 250 Fg-1 in EMITFSI at 60°C, a very interesting result in view of application of such pMeT in IL-based hybrid supercapacitors. Here are reported the results of the galvanostatic polymerization of pMeT in EMITFSI-HTFSI as well as the performance in EMITFSI at 60°C of the obtained pMeT electrode
TransCap: a monolithically integrated supercapacitor andelectrolyte-gated transistor
No full textWe report the proof-of-concept of the TransCap, a monolithically integrated device that exhibits the storage properties of a supercapacitor and the low-voltage operation of an electrolyte-gated transistor. The proof-of-concept is based on coupling a polymer channel with a high surface area carbon gate, employing an ionic liquid as the electrolyte. The possibility to recover the stored energy from the TransCap permits us to use it to power different microelectronic components
Eumelanin electrodes in buffered aqueous media at different pH values
No full textEumelanin, a quinone-based biomacromolecule, is the most common form of the biopigment melanin in the human body. Eumelanin has attracted great interest due to its physicochemical properties, such as metal-ion chelation, free radical scavenging, hydration-dependent (photo) electrical response and redox activity. Investigating the electron transfer properties of eumelanin is key to exploiting the electrochemical energy storage properties of the pigment. In this work, we investigated the redox behavior of chemically controlled eumelanin in NaCH3COO buffer solutions, at different pH values. For our study we used cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge and discharge. Eumelanin, in combination with aqueous electrolytes, provides an attractive case study for eco-designed storage devices based on abundant and environmentally benign materials and interfaces
PtRu catalyst electrodeposited on carbon carbons of high specific surface area for DMFCs
No full textDirect methanol fuel cells (DMFCs) are receiving much attention as power sources for automotive applications and these FCs compared to the polymer membrane fuel cells (PMEFCs) fed by hydrogen present some advantages such as an easier fuel feeding and storage but also some disadvantages. One disadvantage is that DMFCs require optimized electrocatalysts also at the negative electrode for methanol oxidation.
Carbon supported PtRu catalysts are recognized as the most promising and optimized Pt-to- Ru atomic ratio, nanometric dimensions of the particles and their uniform distribution on carbon support enhance the catalytic activity towards the methanol oxidation. To optimize the mass- specific activity of carbon supported PtRu catalysts we focused our research activity on PtRu catalysts electrodeposited on carbon-Nafion supports prepared with different carbons of high specific surface area [1,2].
The results of the electrochemical, structural and morphological characterisations of such supported PtRu catalysts are presented in this contribution to evidence how carbon-Nafion supports of different accessible surface area, different electrodeposition conditions, and different Pt-to-C mass ratio, affect the mass- specific activity of the PtRu catalysts for methanol oxidation in DMFC
Batteries
No full textThis chapter is not intended as an exhaustive treatment of batteries as such. Rather, it seeks to bring to the fore the wide-ranging importance of one application of electron transfer: batteries. Of no less importance in this connection is the enormous effort of interdisciplinary research needed to develop batteries responsive to scientific advances and technological innovations-research that is strengthened under
the pressure of market demand
Low voltage electrolyte-gated organic transistors making use of high surface area activated carbon gate electrodes
No full textIn electrolyte-gated transistors, the exceptionally high capacitance of the electrical double layer forming at
the electrolyte/transistor channel interface permits current modulations of several orders of magnitude, at
relatively low gate voltages. The effect of the nature of the gate electrode on the performance of
electrolyte-gated transistors is still largely unclear, despite recent intensive efforts. Here we demonstrate
that the use of high surface area, low cost, activated carbon gate electrode enables low voltage (sub-1 V)
operation in ionic liquid-gated organic transistors and renders unnecessary the presence of an external
reference electrode to monitor the channel potential, thus dramatically simplifying the device structure.
We used the organic electronic polymer MEH-PPV (poly[2-methoxy-5-(20-ethylhexyloxy)-p-phenylene
vinylene), as the channel material, and the high ionic conductivity, low viscosity ionic liquid [EMIM][TFSI]
(1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), as the electrolyte gating material. We
believe that this will prove to be the first of a new generation of low voltage electrolyte-gated transistors
for applications in organic printable electronics
- …
