ae9b02250_si_001.pdf (2.12 MB)
Iron Phosphide Doped, Porous Carbon as an Efficient Electrocatalyst for Oxygen Reduction Reaction
journal contribution
posted on 2020-02-24, 20:16 authored by Nazgol Norouzi, Fatema A. Choudhury, Hani M. El-KaderiFinding alternative catalysts as
a replacement for platinum in
fuel cells to perform oxygen reduction reaction (ORR) is vital for
the widespread use of fuel cell technology. The scarcity and high
cost of platinum combined with its vulnerability to poisoning by fuel
crossover greatly impede effective use of fuel cells. In this study,
a simple and cost-effective synthesis using triphenylphosphine and
iron(II) chloride was developed to produce highly porous P and Fe-doped
carbon (PFeC, SABET = 967 m2 g–1) with Fe and P contents of 9.8 and 4.1 at. %, respectively. This
synthetic route also generates Fe2P particles, active centers,
supported on P-doped porous carbon which was found to be electrochemically
active toward ORR in both alkali and acidic media. The optimized PFeC
electrocatalyst has a competitive onset and half-wave potential in
comparison to commercially available Pt/C (20 wt %), and it selectively
reduces O2 via a single-step 4e– reaction
pathway. The PFeC electrocatalyst exhibits superior long-term stability
of 90% for the duration of a 15 h chronoamperometry test and inertness
toward the oxidation of methanol. The superior electrocatalytic performance
is credited to the synergistic effects between the P and Fe atoms,
in the form of well-defined and well-distributed nanoparticles confined
in highly porous carbon nanosheets. The enhancement in electrochemical
activity is also credited to the exposed active sites on the surface
of the PFeC sheets and the high conductivity of the conjugated carbon
backbone induced by uniform dopant disruption of the electroneutrality
of carbon. The large surface area of PFeC and its well-developed porous
structure increase the points of contact for adsorption and rapid
transportation of the reactants and improve the overall electrocatalytic
activity of PFeC.