PtIr/C electrocatalysts for ethanol electro-oxidation in
alkaline medium
Jamil M. S. Ayouba, Sirlane G. da Silvaa, Júlio César M. da Silvaa, Mônica H. M. T.
Assumpçãoa, Rodrigo F. B. de Souzaa, Guilherme S. Buzzoa, Estevam V. Spinacéa,
Mauro C. dos Santosb, Almir O. Netoa
a
Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, Av. Prof. Lineu
Prestes, 2242 Cidade Universitária, CEP 05508-900,São Paulo, SP, Brazil
b
Universidade Federal do ABC, Centro de Ciências Naturais e Humanas, Rua Santa
Adélia, 166, Bairro Bangu, CEP 09210-170, Santo André-SP, Brazil
[email protected]
PtIr/C electrocatalysts (Pt:Ir atomic ratios of 90:10, 80:20, 70:30 and 50:50)
support on Vulcan XC72 were prepared by borohydride reduction process using
H2PtCl6·6H2O and IrCl3 as metal sources. The electrocatalysts were characterized by
X-ray diffraction, transmission electron microscopy and cyclic voltammetry. The X-ray
diffraction measurements suggested the PtIr alloy formation, furthermore the peaks of
IrO2 were not observed, nevertheless the presence of Ir oxides in small amounts and
amorphous forms cannot be discarded. The transmission electron microscopy showed
the average particle diameter between 4.5 and 6.0 nm for all compositions prepared.
The catalytic activity for ethanol electro-oxidation in alkaline medium were
investigated by cyclic voltammetry (CV) and chronoamperometry (CA) at room
temperature showed that PtIr/C (50:50) exhibited higher performance for ethanol
oxidation than all other PtIr/C prepared and Pt/C, while the experiments on a single
direct ethanol alkaline fuel cell at 75oC showed PtIr (90:10) as the best electrocatalyst
and Ir/C was virtually inactive for ethanol oxidation in real conditions of operation.
The best results obtained using PtIr/C may be associated to the electronic effect
between Pt and Ir that might cause a decrease of poisoning on catalyst and also the
occurrence of bifunctional mechanism.
Keywords: Direct ethanol alkaline fuel cell, PtIr/C, electrocatalysts.
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