Impacts of anions on the electrochemical oxygen reduction reaction activity and stability of Pt/C in alkaline electrolyte

Pt is the benchmark oxygen reduction reaction (ORR) catalyst for the anion exchange membrane fuel cells. In this paper, we have done systematic studies on the influence of anions (F-, Cl-, Br-, I-, CO32- SO42-, SO32- and S2-) to the ORR activity and durability of Pt/C in alkaline condition. It was found that the anions have less impact to Pt/C in alkaline than in acid. I-, SO32-, and S2- have the poisoning effect and the other anions do not influence the ORR activity significantly. In the accelerating durability test, SO32- and S2- promote the degradation of the Pt/C catalysts. It was found that the impacts of anions are relative to the standard reduction potential of the anions. The anions with low potential have poisoning impact to the activity and durability of Pt/C. This study provides fundamental understandings of the impacts of anions on Pt/C, which may give insights in design of anion exchange membrane fuel cells. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.