Rationally constructing nitrogen–fluorine heteroatoms on porous carbon derived from pomegranate fruit peel waste towards an efficient oxygen reduction catalyst for polymer electrolyte membrane fuel cells

Abstract

N and F heteroatom dual-doping is directed to regulate the defects and texture of porous carbon derived from pomegranate fruit peel wastes (N–F/PGPC), and is responsible for creating active sites favorable for oxygen reduction reaction (ORR). The N–F/PGPC catalyst shows absolute tolerance to methanol and longer stability, with no degradation of ORR activity both in alkaline and acidic media, which makes it a potential metal-free ORR catalyst for the polymer electrolyte membrane fuel cell (PEMFC). The high electrocatalytic activity of N–F/PGPC is primarily due to the presence of hierarchical porous structure, maximum C–C bond polarization, charge re-distribution and high-spin-density-induced defects in the carbon matrices with the existence of N and F heteroatoms. Co-existence of N, in the form of pyridinic-N, pyrrolic-N, graphitic-N, active species, and F, in the form of C–F ionic and C–F semi-ionic active forms, synergistically enhances the ORR catalytic activity. This study offers a process for successfully transforming a highly abundant agricultural product to a commercially worthwhile, alternative low-cost ORR electrocatalyst that holds great promise towards PEMFCs.