Catalysts for direct ethanol fuel cells

Fuel cell technology is currently shifting very fast from fundamental research to real development. In addition to other aspects, this transition is possible because of the important improvements achieved in the field of electrocatalysis in the past decade. This perspective will give a focused overview summarizing the most outstanding contributions in the last 10 years in terms of activity and durability of the catalyst materials for ethanol oxidation and oxygen reduction reaction, respectively. In addition, it provides an outlook about new catalyst support materials with improved performance/stability, advanced characterization techniques, and fundamental studies of reaction mechanisms and degradation processes. All the studies referred to in this perspective significantly contribute to reaching the technical targets for PEFC commercialization.

Electrocatalysis for Polymer Electrolyte Fuel Cells: Recent Achievements and Future Challenges

Ethanol oxidation on Pt is a typical multistep and multiselectivity heterogeneous catalytic process. A comprehensive understanding of this fundamental reaction would greatly benefit design of catalysts for use in direct ethanol fuel cells and the degradation of biomass-derived oxygenates. In this work, the reaction network of ethanol oxidation on different Pt surfaces, including close-packed Pt{111}, stepped Pt{211}, and open Pt{100}, is explored thoroughly with an efficient reaction path searching method, which integrates our new transition-state searching technique with periodic density functional theory calculations. Our new technique enables the location of the transition state and saddle points for most surface reactions simply and efficiently by optimization of local minima. We show that the selectivity of ethanol oxidation on Pt depends markedly on the surface structure, which can be attributed to the structure-sensitivity of two key reaction steps: (i) the initial dehydrogenation of ethanol and (ii) the oxidation of acetyl (CH3CO). On open surface sites, ethanol prefers C-C bond cleavage via strongly adsorbed intermediates (CH2CO or CHCO), which leads to complete oxidation to CO2. However, only partial oxidizations to CH3CHO and CH3COOH occur on Pt{111}. Our mechanism points out that the open surface Pt{100} is the best facet to fully oxidize ethanol at low coverages, which sheds light on the origin of the remarkable catalytic performance of Pt tetrahexahedra nanocrystals found recently. The physical origin of the structure-selectivity is rationalized in terms of both thermodynamics and kinetics. Two fundamental quantities that dictate the selectivity of ethanol oxidation are identified: (i) the ability of surface metal atoms to bond with unsaturated C-containing fragments and (ii) the relative stability of hydroxyl at surface atop sites with respect to other sites.

Comprehensive mechanism and structure-sensitivity of ethanol oxidation on platinum: new transition-state searching method for resolving the complex reaction network.

Parallel pathways of ethanol oxidation: The effect of ethanol concentration

Ethanol electro-oxidation on carbon-supported Pt, PtRu and Pt3Sn catalysts: A quantitative DEMS study

The electrochemical oxidation of ethanol on platinum, rhodium, and platinum−rhodium electrodes is studied using on-line differential electrochemical mass spectrometry (DEMS) and in-situ infrared sp...

Electro-oxidation of ethanol on Pt, Rh, and PtRh electrodes. A study using dems and in-situ FTIR techniques

The reactivity of five-coordinate Ru(II) (1,4-bis(diphenylphosphino)butane) complexes with the N-donor ligands: ammonia, pyridine, 4-substituted pyridines, 2,2′-bipyridine, bis(o-pyridyl)amine, 1,10-phenanthroline, 4,7-diphenylphenanthroline and ethylenediamine

O artigo apresenta uma revisao de estudos publicados sobre Iniciacao Cientifica no Brasil, tomando por base levantamento das publicacoes academicas sobre o tema, que abrangeu o periodo de 1983 ao primeiro semestre de 2007. Na literatura examinada foram encontrados elementos valiosos para a compreensao do estagio em que se encontram importantes questoes pertinentes a Iniciacao Cientifica. A emergencia do campo de estudo e suas principais abordagens estao aqui descritas.

/pdf/estudos-sobre-iniciacao-cientifica-no-brasil-uma-revisao-2sko2gnn6y.pdf

Estudos sobre iniciação científica no Brasil: uma revisão

O artigo toma por base investigacoes realizadas sobre as atividades desenvolvidas por alunas de graduacao, enquanto estudantes de iniciacao cientifica, em laboratorio de pesquisa na area de quimica O principal objetivo do estudo foi investigar o entendimento das alunas no que diz respeito a natureza da ciencia, quando submetidas a esse tipo de instrucao academica Os dados obtidos por meio de entrevistas com docentes e estudantes foram analisados segundo estudos em sociologia da ciencia realizados por LATOUR e WOOLGAR

https://www.scielo.br/pdf/ciedu/v10n1/03.pdf

Do fazer ao compreender ciências: reflexões sobre o aprendizado de alunos de iniciação científica em química

A utilizacao de textos de divulgacao cientifica no ensino formal tem sido discutida com frequencia por pesquisadores brasileiros que atuam na area de educacao em ciencias. Estudos recentes revelam as potencialidades de tal uso no desenvolvimento de habilidades importantes para a formacao dos estudantes. Neste trabalho identificamos, por meio de uma revisao da literatura, as pesquisas realizadas e os objetivos buscados quando textos de divulgacao cientifica sao empregados como recurso didatico no ensino de ciencias, no contexto nacional. Para a identificacao e analise dos dados foi utilizada a Analise de Conteudo proposta por Bardin.

https://dialnet.unirioja.es/descarga/articulo/6170783.pdf

Salete Linhares Queiroz

Papers

Electro-oxidation of ethanol on Pt, Rh, and PtRh electrodes. A study using dems and in-situ FTIR techniques

The reactivity of five-coordinate Ru(II) (1,4-bis(diphenylphosphino)butane) complexes with the N-donor ligands: ammonia, pyridine, 4-substituted pyridines, 2,2′-bipyridine, bis(o-pyridyl)amine, 1,10-phenanthroline, 4,7-diphenylphenanthroline and ethylenediamine

Estudos sobre iniciação científica no Brasil: uma revisão

Do fazer ao compreender ciências: reflexões sobre o aprendizado de alunos de iniciação científica em química

Textos de Divulgação Científica no Ensino de Ciências: uma revisão