Niobium- and antimony-doped tin dioxide aerogels as new catalyst supports for PEM fuel cells

Abstract

The final publication is available at Springer via http://dx.doi.org/10.1007/s10853-016-9833-7International audienceIn order to tackle the problem of low durability, tin dioxide was studied to replace carbon black as a catalyst support in proton exchange membrane fuel cells (PEMFCs). SnO2 is a well-known n-type semi-conductor whose electronic conductivity can be improved by doping with hypervalent cations such as Nb5+ or Sb5+. In addition, as a catalyst support, this material has to develop a high specific surface area with an adequate mesoporous morphology to allow both good dispersion and activity of the catalyst (Pt). To this end, our objective was to develop doped SnO2 aerogels in order to gather in a same material both a high electronic conductivity and an adapted morphology. In this study, SnO2 xerogels and aerogels were successfully synthesized following an acid-catalyzed sol–gel route starting with metal alkoxides as precursors. Dried gels were calcined for 5 h at 600 °C in flowing air. The effect on both the structure and the morphology of the material resulting from doping with niobium or antimony was investigated by XRD, SEM, and nitrogen sorption. The electronic conductivity of pure and doped SnO2 materials was obtained from impedance spectroscopy and resistance measurements. Our materials showed a very interesting airy morphology adapted for the foreseen application: a reasonable specific surface area (80–90 m2/g) with a bimodal pore size distribution centered on around 25 and 45 nm. Moreover, all Sb-doped samples exhibited significant improvement in electronic conductivity. 5 at.% Sb-doped SnO2 even showed an electronic conductivity of 1 S/cm, very similar to that of Vulcan XC-72 (4 S/cm) and representing a 5 orders of magnitude increase compared to that of pure SnO2

Modern Inorganic Aerogels

“…Most of the approaches reported to date follow the classical gelation mechanism and are summarized elsewhere. [7,[131][132][133][134] Current research in the field of the classical gelation approach to metal oxide aerogels focuses on the improvement of the electrical, [135,136] thermal, [137] and mechanical properties. [130] This alternative approach resolved the problems of the commercial availability and the difficult hydrolysis kinetics of the alkoxide precursors especially for the preparation of mixed transition metal oxide aerogels.T he method was extended to several metal oxide systems such as Al 2 O 3 ,C eO 2 ,Z nO,S nO 2 ,T iO 2 , SiO 2 ,NiO 2 ,Fe 2 O 3 ,and others.…”

“…[130] This alternative approach resolved the problems of the commercial availability and the difficult hydrolysis kinetics of the alkoxide precursors especially for the preparation of mixed transition metal oxide aerogels.T he method was extended to several metal oxide systems such as Al 2 O 3 ,C eO 2 ,Z nO,S nO 2 ,T iO 2 , SiO 2 ,NiO 2 ,Fe 2 O 3 ,and others. [7,[131][132][133][134] Current research in the field of the classical gelation approach to metal oxide aerogels focuses on the improvement of the electrical, [135,136] thermal, [137] and mechanical properties. [138] TheLeventis group in particular has made strong contributions to the field of oxidic aerogels by changing and improving the mechanical properties of the materials.…”

Sb-Doped SnO2Aerogels Based Catalysts for Proton Exchange Membrane Fuel Cells: Pt Deposition Routes, Electrocatalytic Activity and Durability

“…[18][19][20] SnO 2 is a n-type semi-conductor but its electronic conductivity can be enhanced by doping with hypervalent donor elements. [21][22][23] Most of the dopant elements added to the SnO 2 matrix are known to inhibit particle growth and modify the material morphology. 21,24 Nb- [25][26][27][28] or Sb- 25,26,[29][30][31][32][33][34][35][36][37] doped SnO 2 materials have already been tested as catalyst support.…”

Moderne Anorganische Aerogele

“…[3][4][5][127][128][129] Besondere Aufmerksamkeit weckte die Arbeit von Gash et al,i nd er sie Propylenoxid als einen effektiven Reaktanten zur Herstellung von Metalloxidgelen einführten, was den Bedarf der üblicherweise genutzten giftigen und teuren Alkoxidvorstufen überflüssig machte. [7,[131][132][133][134] Aktuelle Forschungen im Feld des klassischen Gelbildungsansatzes fürM etalloxidaerogele konzentrieren sich auf die Verbesserung der elektrischen, [135,136] thermischen [137] und mechanischen Eigenschaften. Die Methode wurde auf verschiedene Metalloxidsysteme wie Al 2 O 3 ,C eO 2 ,Z nO,S nO 2 ,T iO 2 ,S iO 2 ,N iO 2 und Fe 2 O 3 erweitert.…”

“…Die Methode wurde auf verschiedene Metalloxidsysteme wie Al 2 O 3 ,C eO 2 ,Z nO,S nO 2 ,T iO 2 ,S iO 2 ,N iO 2 und Fe 2 O 3 erweitert. [7,[131][132][133][134] Aktuelle Forschungen im Feld des klassischen Gelbildungsansatzes fürM etalloxidaerogele konzentrieren sich auf die Verbesserung der elektrischen, [135,136] thermischen [137] und mechanischen Eigenschaften. [138] Durch die Veränderung und Verbesserung der mechanischen Eigenschaften hat insbesondere die Leventis-Gruppe einen wichtigen Beitrag zum Feld der oxidischen Aerogele geleistet.…”