Phenyl-Free Polynorbornenes for Potential Anion Exchange Ionomers for Fuel Cells and Electrolyzers

Ionomers in the catalyst layer play a critical role in the performance of fuel cells and electrolyzers. Phenyl adsorption on hydrogen oxidation catalysts and electrochemical oxidation of phenyl moieties on oxygen evolution catalysts are detrimental to the alkaline devices' performance. Here the adsorption energy of phenyl-containing ionomers is compared to provide the rationale for implementing phenyl-free ionomers. Density functional theory calculations indicated that the norbornane fragment has minimal adsorption energy on Pt(111) due to the absence of aromatic pi electrons. A soluble quaternized polynorbornene ionomer is prepared by vinyl addition polymerization, and it exhibits high performance in both fuel cells and electrolyzers, proving the advantage of the phenyl-free structure. This study establishes the phenyl adsorption energy-electrode performance relationship, highlighting the importance of material interactions between the catalysts and ionomers.

Automated summary

Ionomers in the catalyst layer have a significant impact on the performance of fuel cells and electrolyzers. The adsorption of phenyl and electrochemical oxidation of phenyl moieties can negatively affect the alkaline devices' performance. This study compares the adsorption energy of phenyl-containing ionomers and demonstrates the advantage of phenyl-free structures. The findings highlight the importance of material interactions between catalysts and ionomers and establish the relationship between phenyl adsorption energy and electrode performance.