Flame spray pyrolysis of tin oxide-based Pt catalysts for PEM fuel cell applications
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Flame spray pyrolysis of tin oxide-based Pt catalysts for PEM fuel cell applications Paul I. Dahl1,*, Luis C. Colmenares1,2, Alejandro O. Barnett1, Scott Lomas1, Per E. Vullum1, Jannicke H. Kvello1, Julian R. Tolchard1, Sidsel M. Hanetho1, Tommy Mokkelbost1 1 2
SINTEF Materials and Chemistry, NO-7465 Trondheim, Norway Current address: IK4-CIDETEC. Unit of Materials for Energy, 2014 San Sebastián, Spain
*Corresponding author: [email protected] ABSTRACT SnO2 doped with Sb and Nb has been investigated for its use as catalyst support materials replacing carbon to enhance PEM fuel cells stability. Nanostructured powders of various doping levels were prepared by flame spray pyrolysis (FSP). The specific requirements of surface area >50 m2g-1 and electronic conductivity >0.01 Scm-1 were obtained, and pore sizes ranging mainly from 10 to 100 nm. Pt particles (9-20 wt.% in loading targeted) of a1 nm well dispersed in Sbdoped SnO2 was prepared by a one-step FSP procedure providing microstructures of high interest for further investigations as cathode in PEM fuel cells. INTRODUCTION Nanostructured materials are gaining widespread use, requiring new approaches to powder synthesis with respect to increased production while maintaining proper safety procedures and requested material properties. Flame spray pyrolysis (FSP) is an excellent tool for pioneering development of complex nanomaterials for various applications and is also a scalable process already being investigated by commercial powder producers [1]. Such nanomaterials are of interest for electrodes in various energy applications such as PEM fuel cells (PEMFCs) where high conductivity, high surface area, well defined and sustainable pore structure/size distribution, stability and corrosion resistance are required material properties [2, 3]. In the present work FSP is applied to produce and investigate properties of tin-based oxide materials to be used as cathode catalyst support in PEMFCs, offering high electrochemical stability and corrosion resistance for this application as compared to carbon [4-6]. SnO2-based materials synthesized by FSP are already reported in the literature for gas sensor applications [710], however, FSP is to our knowledge not applied for supported catalyst particles for PEMFCs. SnO2 is a semiconductor, and in this work we elaborate on using antimony and niobium as dopants (Sn1-xMxO2±G, x=0.00-0.15, M=Sb/Nb). Sb is introduced to enhance the electronic conductivity, required for the PEMFCs' support material, while Nb is added with the intention of supressing the segregation of Sb to the surface, as observed in contact with Pt-catalyst particles [11]. The synthesized support powders are compared with the same compositions prepared by co-precipitation (Co-P). Pt-catalyst is introduced to the SnO2-based support through a direct onestep FSP synthesis and the results are compared against Pt deposited through well-established polyol-based and formic acid based deposition routes. In addition to the benefit of being a simple, one-step synthesis r
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