Facile and scalable functionalization of carbon nanofibers for oxygen reduction reaction: Role of nitrogen precursor and non-ionic dispersant

The surface modification of carbon nanomaterials with heteroatoms improves their electrocatalytic activity for oxygen reduction reaction (ORR). The present work reports the surface modification of carbon nanofiber (CNF) with poly(diallyldimethylammonium) chloride (PDDA) and Triton X-100. PDDA behaves as an electron-acceptor, and the intermolecular charge transfer from CNF to PDDA creates delocalized positive charge sites at the edge and basal plane sites of CNF. Triton X-100 disperses CNF, but also acts as a masking agent to obstruct the intermolecular charge transfer between CNF and PDDA. The surface modification of CNF with (PDDA + Triton X-100) is characterized in terms of FESEM, TEM, EDX, Raman, FTIR and TGA. The electrocatalytic activity of the conjugated systems (CNF + PDDA and CNF +Triton X-100+PDDA) is investigated in terms of cyclic voltammetry and linear sweep voltammetry. The reduction of oxygen at PDDA-CNF occurs via a more efficient four-electron (n = 3.9) pathway in 0.1 M KOH and exhibits a limiting diffusion current density of 3.23 mAcm(-2), which is closer to the Pt/C electrode (3.41 mAcm(-2)). PDDA-CNF even outperforms PDDA-CNT or graphene for the ORR performance owing to their special morphological features. This study thus provides a facile and viable strategy for the scalable production of CNF based ORR electrocatalysts. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The surface modification of carbon nanomaterials with heteroatoms enhances their electrocatalytic activity for oxygen reduction reaction. PDDA and Triton X-100 have different effects on the surface modification of carbon nanofibers, affecting electron acceptance and intermolecular charge transfer. The conjugated systems exhibit higher efficiency and current density closer to platinum for oxygen reduction reaction.