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Doctoral Thesis
DOI
10.11606/T.85.2013.tde-01102013-153858
Document
Author
Full name
Ricardo Rodrigues Dias
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2013
Supervisor
Committee
Oliveira Neto, Almir (President)
Ett, Gerhard
Farias, Luciana Aparecida
Forbicini, Christina Aparecida Leão Guedes de Oliveira
Santos, Ivan
Title in Portuguese
Estudo dos eletrocatalisadores de PtSnRh/C + CeO2 preparados pelo método da redução por álcool para a oxidação eletroquímica do etanol
Keywords in Portuguese
CeO2
eletrocatalisadores
etanol
oxidação
PtSnRh
Abstract in Portuguese
Os eletrocatalisadores PtRh (50:50)/85% C + 15% CeO2, PtRh (90:10)/ 85% C + 15% CeO2, PtSn (50:50)/ 85% C + 15% CeO2 e PtSnRh/85% C + 15% CeO2 Todos os eletrocatalisadores foram caracterizados físico-quimicamente pelas técnicas de difração de raios X (DRX) e microscopia eletrônica de transmissão (MET). Por meio das análises de DRX foi observada a presença a estrutura cúbica de face centrada típica de platina e suas ligas, além de uma fase de SnO, em diferentes composições atômicas, foram preparados pelo método da redução por álcool para serem testados nos estudos de oxidação eletroquímica de etanol. 2 para os eletrocatalisadores de PtSn/85% C + 15% CeO2 e PtSnRh/85% C + 15% CeO2. A MET permitiu a observação de uma distribuição relativamente homogênea das partículas, cujos tamanhos médios variaram de 2,5 a 3 nm, no suporte de C + CeO2 As caracterizações eletroquímicas foram realizadas por meio das técnicas de voltametria cíclica (VC) e cronoamperometria (CA). As medições foram feitas à temperatura ambiente e à 50°C, e a técnica de preparo do eletrodo de trabalho foi a de camada fina porosa. . O eletrocatalisador PtSnRh (50:45:5)/ 85% C + 15% CeO2 Na síntese do eletrocatalisador de PtSnRh (50:45:5)/ 85% C + 15% CeO apresentou o melhor desempenho para a oxidação do etanol de acordo com as técnicas eletroquímicas utilizadas, bem como pelos estudos em condições reais de operação em células a combustível alimentadas diretamente por etanol. 2 Estudos com a técnica de infravermelho confirmaram que a oxidação do etanol ocorreu de forma incompleta para os eletrocatalisadores ternários de PtSnRh (50:45:5)/ 85% C + 15% CeOa ordem de adição dos metais foi feita de duas maneiras distintas. O estanho adicionado numa primeira etapa seguida pela adição de PtRh mostrou ser a forma que resultou em maior atividade para a oxidação do etanol. 2 e PtSnRh (50:45:5)/C.
Title in English
Study of electrocatalysts PtSnRh/C + CeO2 prepared by alcohol reduction method for ethanol electro-oxidation
Keywords in English
CeO2
electrocatalysts
ethanol
oxidation
PtSnRh
Abstract in English
PtRh (50:50)/ 85% C + 15% CeO2, PtRh (90:10)/ 85% C + 15% CeO2, PtSn (50:50)/ 85% C + 15% CeO2 and PtSnRh/85% C + 15% CeO2 All catalysts were characterized by the physical chemical techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM). By means of XRD it could be observed the presence of the face-centered cubic structure, which is typical of platinum and its alloys. As well, it was noticed a phase of SnOelectrocatalysts were prepared, with different atomic compositions, by the reduction by alcohol method in order to be tested in the ethanol electrochemical oxidation studies. 2 for the diffractograms of PtSn/85% C + 15% CeO2 and PtSnRh/85% C + 15% CeO2 electrocatalysts. TEM allowed the observation of a relatively homogeneous distribution of particles whose average size ranged from 2.5 to 3 nm in C + CeO2 The electrochemical characterizations were carried out by means of cyclic voltammetry (CV) and chronoamperometry (CA) both at room temperature and 50°C. Thin porous coating technique was used for all ethanol electrochemical oxidation studies. PtSnRh (50:45:5)/ 85% C + 15% CeO support. 2 For the synthesis proceeding of PtSnRh (50:45:5)/ 85% C + 15% CeO electrocatalyst showed the best performance for the ethanol oxidation according to the electrochemical techniques used, as well as by direct ethanol fuel cell tests. 2 FTIR studies confirmed that ethanol oxidation was incomplete for the ternary catalysts of PtSnRh (50:45:5)/ 85% C + 15% CeOelectrocatalyst, the metal addition order was made in two different ways. When tin was added in the first step followed by addition of PtRh to prepare the catalyst, the highest current values for the ethanol oxidation were noticed. 2 and PtSnRh (50:45:5)/C
 
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Publishing Date
2013-10-03
 
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