1,721,061 research outputs found
Polymer electrolyte fuel cells based on bimetal carbon nitride oxygen reduction reaction (ORR) electrocatalysts
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Electrocatalysts based on mono/plurimetallic carbon nitrides for polymer electrolyte membrane fuel cells fuelled with hydrogen (PEFC) and methanol (DMFC) and for H2 electrogenerators
No full textThe invention describes the preparation of electrocatalysts, both anodic (aimed at the oxidation of the fuel) and cathodic (aimed at the reduction of the oxygen), based on mono- and plurimetallic carbon nitrides to be used in PEFC (Polymer electrolyte membrane fuel cells), DMFC (Direct methanol fuel cells) and H2 electrogenerators. The target of the invention is to obtain materials featuring a controlled metal composition based on carbon nitride clusters or on carbon nitride clusters supported on oxide-based ceramic materials. The preparation protocol consists of three steps. In the first the precursor is obtained through reactions of the type: a) sol-gel; b) gel-plastic; c) coagulation-flocculation-precipitation. The second step consists of the thermal treatments to decompose the precursors in an inert atmosphere leading to the production of the carbon nitrides. In the last step the chemical and electro-chemical activation of the electrocatalysts is performed. Precursors are obtained through reactions leading to: a) the complexation of a "soft" transition metal with a coordination complex acting as a ligand to obtain clusters; b) 3-D networking of the resulting clusters through suitable organic molecules and/or macromolecules
Broadband Dielectric Spectroscopy and conductivity mechanism of Nafion and inorganic-organic Nafion/oxoclusters hybrids
No full textPreprints of Symposia - American Chemical Society, Division of Fuel Chemistr
Hybrid Inorganic-organic Ion Conducting Polymer Electrolytes: Synthesis, Structure and Conductivity Mechanism
No full textPolymer Electrolytes are competing for a place in the future energy generation, Storage and distribution markets and they are promising for the development of new devices like sensors and actuators. In this context Mie report an overview on the synthesis, Structure, physical and electrical properties of three classes of new electroactive inorganic-organic hybrid materials.
Theflrst class is due to the ORMOCERS-APE (Organically Modified Ceramics As Polymer Electrolytes or ORMOCERS-APE). These materials are three-dimensional networks composed by organic macromolecules linked together by inorganic atoms like Si, Ti, Zr, Al. Inorganic salts can be dissolved in these materials to determine a tailored conductivity. Taking into account, the recent increased interest in the development of Polymer Electrolyte Membrane Fuel Cells (PEMFCs), we include in the present overview the description of two groups of membranes. In the first group we present membranes based on Nafion and inorganic nano-powders.
These materials can be considered as subgroup of the more general class of the (nano) composite polymer electrolytes. In the second group we describe siloxanic proton-conducting membranes that can be considered as an upgrade version of the ORMOCERS-APE.
The second class is that of the Z-lOPEs (Zeolitic Inorganic-Organic Polymer Electrolytes). These materials are three-dimensional networks composed by organic macromolecules linked together by bridging inorganic clusters. The inorganic clusters are formed by the aggregation of two or more inorganic coordination complexes and are positively or negatively charged.
The third class of materials is that of the HGEs (Hybrid inorganic-organic GEls).
These materials can be considered as an upgrade version ofZ-lOPEs in which the organic component instead of being due to macromolecules is based on organic multi-functional molecules
A novel electrolytic complex based on d-MgCl2 and Poly(ethylene glycol) 400.
No full textA delta-MgCl2 was synthesized by reacting metallic magnesium with l-chlorobutane. This salt is extremely anhydrous and shows a high crystallographic disorder and reactivity toward Lewis bases. By using this delta-MgCl2, eight poly(ethylene glycol)/(delta-MgCl2)(x) complexes, with 3.29 x 10-3 less than or equal to x less than or equal to 7.00 x 10-1 were synthetized. The interaction between Mg2+ ion and poly(ethylene glycol) (PEG) ligands was investigated by mid and far FT-IR spectroscopy. It was concluded that in these polymer electrolytes: (a) Mg2+ ions could be accommodated in two distinct distributions of coordination sites and (b) PEG chains present a TGT conformation. Conductivity data of PEG 400/(delta-MgCl2)x was determined by impedance spectroscopy. The room temperature conductivities of these polymer electrolytes are ca. 1.9 x 10-5 S/cm
Magnesium Electrolyte Based on EMImBF4 and -[MgCl2]n for Secondary Magnesium Batteries
No full textthis report, a new magnesium ion electrolyte is proposed, based on δ-[MgCl2]n and ethylmethylimidazolium tetrafluoroborate (EMImBF4) ionic liquid. Anhydrous δ-[MgCl2]n was obtained by reacting metallic magnesium with n-chlorobutane in a strictly anhydrous atmosphere as described elsewhere. δ-[MgCl2]n consists of inorganic polymer chains where Mg atoms are bonded together by chloride bridges. The δ-[MgCl2]n chains show a high crystallographic disorder and reactivity toward Lewis bases. Twelve magnesiumconducting electrolytes with formula EMImBF4/(δ-[MgCl2]n)f with f ranging between 0 and 0.117 were prepared by dissolving directly δ-[MgCl2]n into EMImBF4; f is the molar ratio between δ-[MgCl2]n and EMImBF4. The metal concentration of the electrolytes was determined by ICP-AES. The correlation between structure, thermal properties and conduction mechanism of EMImBF4/(δ-[MgCl2]n)f was investigated by several techniques: (a) Medium- and Far-infrared spectroscopy, to reveal the structural features and interactions between the various components of each electrolyte; (b) Differential Scanning Calorimetry (DSC), to detect the thermal transitions; (c) Broadband Electric Spectroscopy (BES), to investigate the relaxation phenomena taking place in the materials and the conduction mechanism.
In addition, a detailed study of the mechanism of ion conduction in these electrolytes was carried out by BES in the 10E-2 Hz to 10 MHz and -150°C to 150°C frequency and temperature ranges, respectively. These studies were performed by analyzing the imaginary and real components of conductivity and permittivity spectra by suitable models
Structure, properties and conductivity mechanism of {Nafion/[(ZrO2)(SiO2)0.67]}y nanocomposite proton conducting membranes
No full textZeolitic Inorganic-Organic Polymer Electrolytes: synthesis, characterization and ionic conductivity of a material based on oligo(ethylene glycol) 600, (CH3)2SnCl2 and K4Fe(CN)6
No full textBroadband Dielectric Spectroscopy and conductivity in Nafion and inorganic-organic Nafion/oxoclusters hybrids
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