Synthesis and characterization of PtRu/C catalysts obtained by colloidal and deposition methods for fuel cell applications

Abstract

The purpose of this investigation was to compare catalysts produced by the Bönnemann -colloidal method (PtRu (B1) and PtRu (B2)), and those produced by the spontaneous deposition method (PtRu (SD)). The catalysts produced by both methods had good electrochemical behavior for methanol oxidation for proton exchange membrane fuel cell applications. The structure of the catalyst was examined by transmission electron microscopy (TEM). Energy dispersive spectroscopic analysis (EDS) was used to determine the semi-quantitative composition of the catalysts, and the electrochemical behavior was determined by cyclic voltammetry (CV). The diffractograms of the binary catalysts revealed platinum and ruthenium as the only crystalline phases, as per ICDD data base. The PtRu (B1) catalyst, treated in a reducing atmosphere, has the same structure as PtRu (B2), treated in an oxidising/reducing atmosphere, except that the crystallite size was around 1.7 nm for PtRu (B1) instead of 9.9 nm for PtRu (B2). The catalysts PtRu (B2) and PtRu (SD) showed similar cyclic voltammetric behavior, which was better than that of PtRu (B1). Both methods are suitable for the production of electrocatalysts for fuel cell applications. The colloidal method is more expensive than the deposition method, but the former permits the production of ternary and quaternary catalyst systems with enhanced CO tolerance.

Electrochemical and impedance spectroscopy studies in H2/O2 and methanol/O2 proton exchange membrane fuel cells

“…The electrocatalyst preparation should aim at a better nanoparticle distribution on the support and smaller particle sizes. In the literature, numerous efforts involving the electrocatalysts preparation have been reported, ranging from simple reductive precipitation methods [11,12] to the more elaborate colloid [13][14][15] and microemulsion methods [16,17]. A simple and inexpensive way to obtain high quality electrocatalysts is the alcohol reduction process [18][19][20][21][22].…”

Estudo da oxidação eletroquímica do ácido fórmico utilizando eletrocatalisadores Pd/C-Sb2O5.SnO2, PdAu/C-Sb2O5.SnO2, PdIr/C-Sb2O5.SnO2 e PdAulr/C-Sb2O5.SnO2 preparados via redução por borohidreto de sódio

“…As sínteses dos eletrocatalisadores foram investigadas amplamente e são bem conhecidas, no entanto, os diferentes métodos da síntese levam a um comportamento diferente dos eletrocatalisadores [131]. Nesse contexto, muitos trabalhos têm sido feitos para correlacionar os comportamentos eletroquímicos dos eletrocatalisadores.…”

“…Para obter os nanocristais, um coloide estável deve ser preparado numa atmosfera inerte e seco [131] …”

Oxidação eletroquímica do etanol e glicerol em eletrólito alcalino utilizando eletrocatalisadores PdTiO>sub<2>/sub</C preparados via redução por borohidreto de sódio

“…A Este método também é conhecido como coloidal por obter um sistema em coloide estável em uma atmosfera inerte e seca. Ele apresenta três etapas principais: a primeira é a preparação do coloide metálico, a segunda é a deposição dos coloides no suporte de carbono, e a terceira é a redução química da mistura [149,150].…”

“…Franco et al [150] A preparação deste método consiste na utilização de uma solução contendo precursores metálicos (como Pt, Ru, Sn), um suporte de carbono ativo (Vulcan ® XC-72 por exemplo), e um material redutor (NaBH4, Na2S2O3, CH2O2 dentre outros) [159].…”