Hydroxide Degradation Pathways for Substituted Trimethylammonium Cations: A DFT Study

Research output: Contribution to journalArticlepeer-review

186 Scopus Citations

Abstract

Substituted trimethylammonium cations serve as small molecule analogues for tetherable cations in anion exchange membranes. In turn, these membranes serve as the basis for alkaline membrane fuel cells by allowing facile conduction of hydroxide. As these cations are susceptible to hydroxide attack, they degrade over time and greatly limit the lifetime of the fuel cell. In this research, we performed density functional theory calculations to investigate the degradation pathways of substituted trimethylammonium cations to probe the relative durability of cation tethering strategies in alkyl and aromatic tethers. Our results show that significant changes in calculated energy barriers occur when substitution groups change. Specifically, we have found that, when available, the Hofmann elimination pathway is the most vulnerable pathway for degradation; however, this barrier is also found to depend on the carbon chain length and number of hydrogens susceptible to Hofmann elimination. S N2 barriers were also investigated for both methyl groups and substitution groups. The reported findings give important insight into potential tethering strategies for trimethylammonium cations in anion exchange membranes.

Original languageAmerican English
Pages (from-to)9419-9426
Number of pages8
JournalJournal of Physical Chemistry C
Volume116
Issue number17
DOIs
StatePublished - 3 May 2012

NREL Publication Number

  • NREL/JA-2C00-55329

Keywords

  • anion exchange membranes
  • energy barriers
  • fuel cells

Fingerprint

Dive into the research topics of 'Hydroxide Degradation Pathways for Substituted Trimethylammonium Cations: A DFT Study'. Together they form a unique fingerprint.

Cite this