109262-02-4Relevant academic research and scientific papers
Insight into the Alkaline Stability of N-Heterocyclic Ammonium Groups for Anion-Exchange Polyelectrolytes
Chen, Nanjun,Fan, Jiantao,Hu, Chuan,Jin, Yiqi,Lee, Young Moo,Li, Hui,Liu, Haijun,Wu, Bo,Xu, Shaoyi
, p. 19272 - 19280 (2021)
The alkaline stability of N-heterocyclic ammonium (NHA) groups is a critical topic in anion-exchange membranes (AEMs) and AEM fuel cells (AEMFCs). Here, we report a systematic study on the alkaline stability of 24 representative NHA groups at different hydration numbers (λ) at 80 °C. The results elucidate that γ-substituted NHAs containing electron-donating groups display superior alkaline stability, while electron-withdrawing substituents are detrimental to durable NHAs. Density-functional-theory calculations and experimental results suggest that nucleophilic substitution is the dominant degradation pathway in NHAs, while Hofmann elimination is the primary degradation pathway for NHA-based AEMs. Different degradation pathways determine the alkaline stability of NHAs or NHA-based AEMs. AEMFC durability (from 1 A cm?2 to 3 A cm?2) suggests that NHA-based AEMs are mainly subjected to Hofmann elimination under 1 A cm?2 current density for 1000 h, providing insights into the relationship between current density, λ value, and durability of NHA-based AEMs.
