Morphological influence of graphitic carbon nanofibers by N-F dual-doping on Pt electrocatalytic activity and stability for oxygen reduction reaction in polymer electrolyte membrane fuel cells

Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N-F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs-NF-Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N-F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H-NF-Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H-NF-Pt as cathode catalyst with minimum loading of 0.10 mg cm(-2), delivers power density of 0.942 W cm(-2) at current density of 2.50 A cm(-2) without backpressures in H-2 -O-2 feeds. The H-NF-Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The morphology of carbon nanofibers and their interaction with Pt nanoparticles significantly affect the performance of fuel cell electrocatalysts. In this study, the effects of N-F co-doping on the morphology and performance of graphitic carbon nanofibers (GNFs) were investigated. The GNFs-NF-Pt catalysts exhibit enhanced oxygen reduction reaction (ORR) activity and durability, attributed to the morphological evolution and the doped N-F heteroatoms. Among them, the H-NF-Pt catalyst shows outstanding ORR activity and electrochemical stability, with only a 20 mV loss in half-wave potential after 20,000 potential cycling. The PEMFC using H-NF-Pt as a cathode catalyst achieves a power density of 0.942 W cm(-2) at a current density of 2.50 A cm(-2) without backpressures in H-2 -O-2 feeds. The hierarchical architecture of the H-NF-Pt catalyst enables excellent performance at a minimized catalyst loading, thus reducing the overall cost of the fuel cell.