Antimony doped tin oxide modified carbon nanotubes as catalyst supports for methanol oxidation and oxygen reduction reactions
Antimony doped tin oxide (ATO) and its composites with carbon nanotubes (CNTs) were synthesized and investigated as alternative Pt catalyst supports for the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR). The synthesized ATO nanoparticles had a BET surface area of 88 m2 g−1 and an electronic conductivity of 0.75 S cm−1. When loaded on the CNT surface at a content of e.g. 5 wt%, the composite support provided a specific surface area of 243 m2 g−1 and an electronic conductivity of 3.9 S cm−1. Uniformly dispersed platinum nanoparticles were prepared with this composite material as the support. Strong interactions between platinum and oxide particles, as evidenced by XPS, led to modification of the electronic structure of platinum, which in turn significantly enhanced the catalytic activity towards both ORR and MOR. The improved catalytic performance for the ORR was confirmed by high temperature proton exchange membrane fuel cell tests.