Electrospun Carbon Nanofibre‐Based Catalysts Prepared with Co and Fe Phthalocyanine for Oxygen Reduction in Acidic Medium

Abstract

A Pt‐free cathode catalyst is necessary for proton‐exchange membrane fuel cell (PEMFC) to enable the widespread use of these environmentally friendly energy conversion devices at affordable price. Herein, a pyrolyzed electrospun carbon nanofibre (CNF) catalyst is prepared embedded with cobalt(II) phthalocyanine and iron(II) phthalocyanine compounds to provide the transition metal N4‐macrocyclic complex‐derived sites (MNX) possessing better electrocatalytic oxygen reduction reaction (ORR) activity. The physical characterisation showed the nanofibrous structure of catalyst with rough surface texture and considerable amount of N, Fe, and Co. The D−MN4−CNF−IL−A catalyst prepared using ionic liquid as a porogen displayed the best electrocatalytic activity for O2 electroreduction proceeding via 4e− pathway in 0.5 M H2SO4 electrolyte solution with the ORR onset and half‐wave potential of 0.83 and 0.71 V vs reversible hydrogen electrode (RHE), respectively.

Mechanosynthesis of a bifunctional FeNi–N–C oxygen electrocatalyst via facile mixed-phase templating and preheating-pyrolysis

“…Among the three catalysts studied, IroNi-3D exhibited the smallest Tafel slope value of around −53 mV dec −1 , indicating fast electron transfer followed by a slower chemical step. 58,61 This suggests that IroNi-3D possesses higher ORR activity than IroNi-1 and IroNi-2, as its Tafel slope values are closer to −60 mV dec −1 . In order to assess their catalytic performance in the oxygen evolution reaction, the synthesized materials underwent linear sweep voltammetry (LSV) measurements in a 0.1 M KOH solution in an argon-saturated environment with an electrode rotation rate of 1600 rpm.…”

“…This can be ascribed to the synergistic interplay of individual and combined ORR-active sites, where hydrogen peroxide is first formed and further reduced to water. 58 To evaluate the ORR mechanistic pathway on the prepared materials, Tafel plots were constructed using RDE polarization data (Fig. S9†), and the calculated Tafel slope values are summarized in Table S3 †.…”

Atomically dispersed Fe/Co–N–C and their composites for proton exchange membrane fuel cells

“…Besides direct observation through electron microscopy, spectroscopic methods such as X-ray photoelectron spectroscopy (XPS) are also used to analyze the binding conditions and valence states of elements. 86,87 The N 1s peak detected by XPS is always deconvoluted as pyridinic N, graphitic N, pyrrolic N, oxidized N as well as metal–N (Co–N x /Fe–N x ) to resolve the coordinated condition, 85,88,89 in which the metal–N ratio is generally used to evaluate the content of Fe/Co active sites qualitatively. Nevertheless, it is worth noting that XPS analysis cannot resolve the atomic dispersion and coordination environment of metal sites by itself and thus usually has to be combined with other techniques like X-ray absorption spectroscopy (XAS).…”