1,721,186 research outputs found
Pt- and Pd-Based Carbon Nitride ORR Electrocatalysts Supported on Conductive Nanoparticles for Application in PEMFCs
No full textDevelopment of plurimetallic nano-electrocatalysts based on carbon nitride supports for the ORR processes in PEM fuel cells
No full textDevelopment of nano-electrocatalysts based on carbon nitride supports for the ORR Processes in PEM Fuel Cells
No full textThis report describes the development and the optimization of new synthesis routes yielding electrocatalysts for the oxygen reduction reaction (ORR) aimed at application in proton exchange membrane fuel cells (PEMFCs). The preparation protocols consist in the synthesis of two groups of hybrid inorganic-organic precursors, characterized by a different concentration of nitrogen, which subsequently undergo a high-temperature pyrolysis in inert atmosphere, washing and activation. The resulting materials show a well-controlled stoichiometry. The nitrogen incorporated in the support transforms the matrix into a supramolecular ligand, and stabilizes the electrocatalyst by coordinating the active metal clusters. The latter are composed of an "active metal" such as Pt or Pd, combined with one or more "co-catalyst" elements such as Au, Fe, Co and Ni. An extensive characterization of the carbon nitride electrocatalysts under the chemical, structural, morphological and electrochemical points of view is described, together with their use in membrane electrode assemblies (MEAs) tested in single fuel cells under operative conditions. Results indicated that the best electrocatalysts are those characterized by a "core-shell" morphology. These systems consist of metal carbon nitride materials with a low concentration of nitrogen (shell) supported on electronically conductive graphite nanoparticles (core). Promising results were obtained both in terms of ORR overpotential (eta) and of mass activity (A(m)). Indeed, eta resulted up to similar to 30 mV lower with respect to reference Pt-based systems, and an A(m), equal to 0.3-0.4g of Pd or Pt to achieve 1 kW was reached
'"Core-shell" electrocatalysts based on mono/plurimetallic carbon nitrides for low-temperature fuel cells (PEMFCs, DMFCs, AFCs and PAFCs) and electrolyzers', brevetto europeo depositato il 22-06-2009.
No full textThis invention describes the preparation of electrocatalysts to be mounted at either the anode or the cathode of fuel cells or of H2 electrolysers. The materials described in this invention are particularly suitable for application in polymer electrolyte membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), alkaline fuel cells (AFCs) and phosphoric acid fuel cells (PAFCs). The target of the invention is the preparation of core-shell electrocatalysts where active metal sites supported on carbon nitride nanoclusters (shell) are supported on suitable electron-conducting materials (core) such as active carbons or metal nanopowders. The prepared materials feature a well-controlled metal composition, and also include the desired amount of nitrogen. 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; d) metal-ligand complexation processes in organic solvent using as a ligand a molecule, a macromolecule or a macromolecular system. The second step consists in a pyrolysis process of the precursor in an inert atmosphere leading to the production of the supported carbon nitride materials. In the last step, the chemical and electrochemical activation of the electrocatalyst is performed. The precursors are obtained through reactions leading to: a) the complexation of a transition metal with another molecule or coordination complex acting as a ligand to obtain clusters; b) the 3-D networking of the resulting clusters through suitable organic molecules and/or macromolecules and/or macromolecular systems on the support
A new plurimetal carbon nitride electrocatalyst for PEMFCs based on Pd, Au and Fe
No full textThis report describes the preparation of a new plurimetal carbon nitride electrocatalyst based on Pd, Au and Fe and how its chemical composition, morphology and electrochemical performance are affected by a series of post-synthesis treatments involving leaching with mineral acids and annealing steps. Cyclic voltammetry with the thin-film rotating ring-disk electrode (CV-TF-RRDE method) is used to study the fundamental ORR electrochemistry and selectivity of the resulting materials. The latter are also studied under operative conditions at the cathode of single fuel cells. The pristine electrocatalyst shows a very promising performance in the ORR. Furthermore, the different post-synthesis treatments allow to identify the role of the various metal species in the active site. Finally, the measurements carried out in a single cell lead to the identification of the main morphological features responsible for obtaining an efficient ORR electrocatalyst
'Produzione in situ di idrogeno tramiteprocesso di splitting di acqua mediato da metalli o da specie inorganiche', brevetto italiano depositato il 10-03-2009
No full textL’invenzione riguarda un processo per produrre idrogeno, ottenuto tramite la reazione chimica di due componenti posti in contatto tra loro in un opportuno apparato. I due componenti reagiscono in atmosfera inerte o riducente. Di conseguenza, l’idrogeno prodotto non reagisce ulteriormente e può essere recuperato ed utilizzato, con particolare riferimento ad applicazioni per celle a combustibile. Il processo proposto è semplice, l’apparato in cui esso viene condotto è di facile progettazione e realizzazione. Si dimostra che la capacità gravimetrica e volumetrica di produzione di idrogeno tramite questo processo può essere competitiva con quella garantita dalle più moderne tecnologie impiegate attualmente. L’idrogeno viene prodotto alla pressione desiderata, solo nel momento in cui viene richiesto, e può presentare un elevato grado di purezza a seguito di un’opportuna scelta dei reagenti
A new Pt-Rh carbon nitride electrocatalyst for the oxygen reduction reaction in polymer electrolyte membrane fuel cells: Synthesis, characterization and single-cell performance
No full textIn this paper the preparation of a new bimetal electrocatalyst for the oxygen reduction reaction (ORR), which is one of the most important bottlenecks in the operation of polymer electrolyte membrane fuel cells (PEMFCs), is described. This material was synthesized through a pyrolysis process of a zeolitic inorganic-organic polymer electrolyte (Z-IOPE-like) precursor, followed by suitable washing and activation procedures of the product. The electrocatalyst, whose active sites consist of platinum and rhodium, was: (a) extensively characterized from the chemical, structural, morphological and electrochemical points of view and (b) used to prepare a membrane-electrode assembly (MEA) which was tested under operative conditions in a single-cell configuration. It was observed that, with respect to a reference material based on supported platinum, rhodium did not compromise the performance of the electrocatalyst in the ORR. This behaviour was interpreted in the framework of a general model concerning the enhancement of ORR performance in bimetal systems supported on carbon nitrides. Finally, the material shows a slightly better tolerance toward a few common contaminants for the ORR such as methanol and chloride anions, typical of direct methanol fuel cells (DMFCs) and vehicular applications, respectively
'Elettrocatalizzatori "nocciolo-guscio" a base di carbonitruri mono/plurimetallici per celle a combustibile a bassa temperatura (PEMFC, DMFC, AFC, e PAFC) ed elettrolizzatori', brevetto italiano depositato il 26-06-2008.
No full textQuesta invenzione descrive la preparazione di elettrocatalizzatori che possono essere montati sia all’anodo che al catodo di celle a combustibile o elettrolizzatori di idrogeno. I materiali descritti in questa invenzione sono particolarmente adatti per applicazioni in celle a combustibile ad elettrolita polimerico (PEMFC), celle a combustibile a metanolo diretto (DMFC), celle a combustibile alcaline (AFC), e celle a combustibile ad acido fosforico (PAFC). L’obiettivo dell’invenzione è la preparazione di elettrocatalizzatori nocciolo-guscio nei quali i siti attivi metallici presenti su nanocluster carbonitrurici (guscio) sono supportati su opportuni materiali conduttori elettronici (nocciolo) come carboni attivi o nanopolveri metalliche. I materiali preparati sono caratterizzati da una composizione chimica ben controllata ed includono anche la quantità di azoto desiderata. Il protocollo di preparazione consiste di tre fasi. Nella prima viene prodotto il precursore tramite reazioni del tipo: a) sol-gel; b) gel-plastico; c) coagulazione-flocculazione-precipitazione; d) processi di complessazione metallo-legante in solvente organico utilizzando come legante una molecola, una macromolecola o un sistema macromolecolare. La seconda fase consiste in un processo di pirolisi del precursore in atmosfera inerte che porta alla produzione dei materiali carbonitrurici supportati. Nell’ultima fase viene effettuata l’attivazione chimica ed elettrochimica dell’elettrocatalizzatore. I precursori sono ottenuti tramite reazioni che portano: a) alla complessazione di un metallo di transizione con un’altra molecola o complesso di coordinazione che agisca da legante per ottenere dei clusters; b) la reticolazione tridimensionale dei clusters ottenuti attraverso opportune molecole e/o macromolecole e/o sistemi macromolecolari sul supporto
Tri-metal Pt-free carbon nitride electrocatalysts for oxygen reduction reaction: synthesis, characterization and electrochemical performance
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