Poly[2,2'-(4,4'-bipyridine)-5,5'-bibenzimidazole] functionalization of carbon black for improving the oxidation stability and oxygen reduction reaction of fuel cells

Mohamed R Berber; Mohamad Y Mustafa

doi:10.1039/d0ra04289g

Poly[2,2'-(4,4'-bipyridine)-5,5'-bibenzimidazole] functionalization of carbon black for improving the oxidation stability and oxygen reduction reaction of fuel cells

RSC Adv. 2020 Aug 20;10(51):30776-30784. doi: 10.1039/d0ra04289g. eCollection 2020 Aug 17.

Authors

Mohamed R Berber^{1

2}, Mohamad Y Mustafa³

Affiliations

¹ Chemistry Department, College of Science, Jouf University Sakaka 2014 Saudi Arabia mrberber@ju.edu.sa.
² Chemistry Department, Faculty of Science, Tanta University Tanta 31527 Egypt mrberber@science.tanta.edu.eg.
³ Institute of Buildings, Energy and Material Technology, Faculty of Engineering Science and Technology, The Arctic University of Norway Norway.

Abstract

The rapid oxidation of carbon black (CB) is a major drawback for its use as a catalyst support in polymer electrolyte fuel cells. Here, we synthesize poly[2,2'-(4,4'-bipyridine)-5,5'-bibenzimidazole] (BiPyPBI) as a conducting polymer and use it to functionalize the surface of CB and homogenously anchor platinum metal nanoparticles (Pt-NPs) on a CB surface. The as-prepared materials were confirmed by different spectroscopic techniques, including nuclear magnetic resonance spectroscopy, energy-dispersive X-ray, thermal gravimetric analysis, and scanning-transmittance microscopy. The as-fabricated polymer-based CB catalyst showed an electrochemical surface area (ECSA) of 63.1 cm² mg_Pt ^-1, giving a catalyst utilization efficiency of 74.3%. Notably, the BiPyPBI-based CB catalyst exhibited remarkable catalytic activity towards oxygen reduction reactions. The onset potential and the diffusion-limiting current density reached 0.66 V and 5.35 mA cm^-2, respectively. Furthermore, oxidation stability testing showed a loss of only 16% of Pt-ECSA for BiPyPBI-based CB compared to a 36% loss of Pt-ECSA for commercial Pt/CB after 5000 potential cycles. These improvements were related to the synergetic effect between the nitrogen-rich BiPyPBI polymer, which promoted the catalytic activity through the structural nitrogen atoms, and demolished the degradation of CB via the wrapping process.