Electrochemical Properties and Durability of Electrocatalysts Supported on SnO_2

摘要

For polymer electrolyte fuel cells (PEFCs), carbon corrosion, leading to lower activities of catalysts under cathode conditions, is one of the important technological issues to be solved. We have been developing SnO_2 and Nb-SnO_2 as alternative support materials. In this study, the oxygen reduction reaction (ORR) activity and the durability of Pt/SnO_2 and Pt/Sn_(0.98)Nb_(0.02)O_2 against voltage cycling between 1.0 and 1.5 V_(RHE) are quantitatively investigated. Longer ORR durability was verified, compared to the standard catalyst, Pt/Vulcan. Furthermore, we have found that the degradation mechanism of ORR is probably different between carbon black and SnO_2-based supports. In the case of SnO_2-based catalysts, degradation arose mainly from the loss of electrochemical surface area (ECSA), while other factors were also involved for Pt/Vulcan. Consequently, SnO_2 is a promising candidate electrocatalyst support material to solve carbon corrosion problems of PEFCs.