Ionomer immobilized onto nitrogen-doped carbon black as efficient and durable electrode binder and electrolyte for polymer electrolyte fuel cells. (20th July 2022)

• Record Type: Journal Article
• Authors: Choi, Won Young; Seo, Dong Jun; Choi, Hyunguk; Lee, Myeong Hwa; Choi, Seo Won; Yoon, Young Gi; Kim, Tae Young; Kim, Hansung; Jung, Chi-Young
• Is Part Of: Electrochimica acta. Volume 421(2022)
• Publication Date: 2022-07-20
• Subjects: Polymer electrolyte fuel cell electrode -- Ionomer immobilized onto nitrogen-doped carbon black -- ORR activity -- Mass transport resistance -- Carbon support degradation; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140427
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: PFSA ionomer/N-doped CB is solely used as electrolyte in the PEFC cathode. Carbon atoms adjacent to nitrogen derive a homogeneous distribution of the ionomer. Cell performance is notably improved by superior activity and O2 transportation. This is attributed to suppression of catalyst poisoning and agglomeration of ionomer. Cell durability is also enhanced due to higher graphitization of N-doped CB. Abstract: An implementation of the polymer electrolyte fuel cell (PEFC) electrode, composed of the perfluorinated sulfonic acid (PFSA) ionomer with unprecedented uniform distribution, has recently gained a great attention due to its positive impact on the cell performance as well as durability. However, an issue with the conventional electrodes is a stronger adsorption of sulfonate terminal groups specifically onto Pt catalyst than carbon black (CB) support, that accelerates an inhomogeneous distribution of the PFSA ionomer. In this work, we report a novel PEFC electrode by introducing the ionomer immobilized onto nitrogen-doped carbon black (I/NCB) as electrode binder as well as electrolyte. The carbon atoms adjacent to nitrogen allow a considerable attraction with sulfonated groups over the NCB surfaces, which creates more homogeneous distribution of ionomer when compared with Pt/CB in the conventional electrode. As compared with the conventional electrode, the electrode employing I/NCB presents a superior activity towards oxygen reduction reaction (Pt mass activity increased from 91.3 to 139.6 A g −1 ) and mass-transport characteristics (mass-transport resistance decreased from 65.9 to 45.5 mΩ cm 2 ), with the cell current density enhanced by 23% at 0.6 V. The enhanced cell durability is confirmed by less degradation in the electrochemically available surface area after the accelerated stress test of carbon support, mainly attributed to the promoted stability of NCB over CB. Given the advances in both performance and durability, the proposed electrode architecture based on I/NCB may provide an alternative pathway in obtaining better electrode kinetics and O2 transport, along with an exceptional resistivity towards the carbon support degradation. Graphical abstract: Image, graphical abstract