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. 2024 Jul 30;10(15):e35483.
doi: 10.1016/j.heliyon.2024.e35483. eCollection 2024 Aug 15.

Elucidating the effects of nitrogen and phosphorus co-doped carbon on complex spinel NiFe2O4 towards oxygen reduction reaction in alkaline media

Siyabonga Patrick Mbokazi  1 , Thabo Matthews  1 , Haitao Zheng  2 , Makhaokane Paulina Chabalala  1 , Memory Zikhali  1 , Kudzai Mugadza  1 , Sandile Gwebu  1 , Lukhanyo Mekuto  3 , Nobanathi Wendy Maxakato  1
Affiliations

Elucidating the effects of nitrogen and phosphorus co-doped carbon on complex spinel NiFe2O4 towards oxygen reduction reaction in alkaline media

Siyabonga Patrick Mbokazi et al. Heliyon. .

Abstract

The study presents for the first time complex spinel NiFe2O4 nanoparticles supported on nitrogen and phosphorus co-doped carbon nanosheets (NPCNS) prepared using sol gel and the carbonization of graphitic carbon nitride with lecithin as a highly active and durable electrocatalyst for oxygen reduction reaction. The physicochemical properties of complex spinel NiFe2O4 on NPCNS and subsequent nanomaterials were investigated using techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical activity of the electrocatalysts was evaluated using hydrodynamic linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. The electrocatalytic performance of the NiFe2O4/NPCNS nanohybrid electrocatalyst is dominated by the 4e- transfer mechanism, with an onset potential of 0.92 V vs. RHE, which is closer to that of the Pt/C, and a current density of 7.81 mA/cm2 that far exceeds that of the Pt/C. The nanohybrid demonstrated the best stability after 14 400 s, outstanding durability after 521 cycles, and the best ability to oxidize methanol and remove CO from its active sites during CO tolerance studies. This improved catalytic activity can be attributed to small nanoparticle sizes of the unique complex spinel nickel ferrite structure, N-Fe/Ni coordination of nanocomposite, high dispersion, substantial ECSA of 47.03 mF/cm2, and synergy caused by strong metal-support and electronic coupling interactions.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
(a) X-ray diffraction patterns of NiFe2O4/NPCNS, Fe2O3/NPCNS, NiO/NPCNS, and NPCNS hybrid nanomaterials, (b) X-ray diffraction patterns of NiFe2O4/NPCNS prepared using the same experimental conditions and subjected to X-ray diffraction analysis after synthesis to show that the preparation method results in complex spinel NiFe2O4 nanoparticles on NPCNS and, (c) FTIR spectra of NiFe2O4/NPCNS, Fe2O3/NPCNS, NiO/NPCNS, and NPCNS hybrid nanomaterials,.
Fig. 2
Fig. 2
SEM micrographs for (a) NiFe2O4/NPCNS, (b) Fe2O3/NPCNS, (c) NiO/NPCNS, (d) NPCNS, and elemental mapping of (e) NiFe2O4/NPCNS showing the (f) C, (g) Fe, (h) Ni, (i) P, (j) O, and (k) N respective elements on that hybrid nanomaterial.
Fig. 3
Fig. 3
TEM images for (a) NiFe2O4/NPCNS, (c) Fe2O3/NPCNS, (e) NiO/NPCNS, and (g) NPCNS with an inlet of SAED for all composites and histograms for particle size distribution on (b) NiFe2O4/NPCNS, (d) Fe2O3/NPCNS, and (f) NiO/NPCNS, and also the lattice fridge for the nanoparticles of NiFe2O4/NPCNS.
Fig. 4
Fig. 4
(a) N2 adsorption-desorption isotherms, (b) corresponding pore size distribution, and (c) RAMAN spectra of NiFe2O4/NPCNS, Fe2O3/NPCNS, NiO/NPCNS, and NPCNS hybrid nanomaterials.
Fig. 5
Fig. 5
XPS spectra after deconvolution for NiFe2O4/NPCNS, Fe2O3/NPCNS, and NiO/NPCNS (a) C 1s spectra, (b) N 1s spectra, (c) O 1s spectra, (d) P 2p spectra, (e) Ni 2p spectra and, (e) Fe 2p spectra.
Fig. 6
Fig. 6
(a) Cyclic Voltammetry (CV) curves towards ORR on the synthesized NiFe2O4/NPCNS, and 20 % Pt/C in an O2-saturated and Ar-saturated 0.1M KOH solution, (b) Linear sweep voltammetry (LSV) curves of the synthesized NiFe2O4/NPCNS, Fe2O3/NPCNS, NiO/NPCNS, NPCNS, and an inlet of the commercial 20 % Pt/C at 1600 rpm and a scan rate:10 mV/s, (c) Tafel slopes of all electrocatalysts in O2 saturated 0.1M KOH solution at 1600 rpm and a scan rate of 10 mv s−1, (d, e) Linear sweep voltammetry (LSV) curves of the synthesized NiFe2O4/NPCNS, NiFe2O4/PCNS, and NiFe2O4/NCNS at 1600 rpm and a scan rate:10 mV/s, and the number of electrons transferred during ORR for all hybrid electrocatalysts, (f) A Nyquist plots for all metal oxide hybrid electrocatalysts including the commercial 20 % Pt/C measured at a potential of 0.29 V and a frequency range of 100 kHz–0.5 Hz, (g) Double layer capacitance obtained from cyclic voltammetric (CV) curves in the non-faradaic region at various scan rates of 10, 30, 50, 70, 90 mV/s in argon saturated 0.1 M KOH electrolyte solution and corresponding capacitive current at 1.06 V against the scan rate for the CV tests, (h) Current–time responses of the synthesized hybrid nanomaterials and commercial 20 % Pt/C in O2 saturated 0.1 M KOH at 0.45 V upon continuous addition of 3.0 M methanol in increments to the electrolyte solution at 1000 s, 3000 s, 5000 s, 7000 s, 9000 s, 11 000 s, and 13 000 s respectively, and (i) Cyclic voltammetry (CV) responses for NiFe2O4/NPCNS in O2 saturated 0.1 M KOH electrolyte before and after adding 3.0 M methanol to evaluate the effect of methanol on the ORR.
Fig. 7
Fig. 7
(a) Stability test results of the synthesized hybrid nanomaterials and commercial Pt/C under continuous O2 reduction at 0.45 V vs. RHE for 4 h, (b) TEM images of NiFe2O4/NPCNS, Fe2O3/NPCNS, NiO/NPCNS, and NPCNS nanomaterials obtained after electrochemical measurements, (c) Durability studies for NiFe2O4/NPCNS in O2 saturated 0.1 M KOH at 100 mV/s, and (d) Cyclic voltammetry curves of NiFe2O4/NPCNS nanocomposite used to study the active sites present on the hybrid electrocatalyst.
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References

    1. Ling T., Yan D.Y., Jiao Y., Wang H., Zheng Y., Zheng X., Mao J., Du X.W., Hu Z., Jaroniec M., Qiao S.Z. Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis. Nat. Commun. 2016;7 doi: 10.1038/ncomms12876. - DOI - PMC - PubMed
    1. Cheng F., Chen J. Metal–air batteries: from oxygen reduction electrochemistry to cathode catalysts. Chem. Soc. Rev. 2012;41:2172–2192. doi: 10.1039/C1CS15228A. - DOI - PubMed
    1. Ren S., Ma S., Yang Y., Mao Q., Hao C. Hydrothermal synthesis of Fe2O3/polypyrrole/graphene oxide composites as highly efficient electrocatalysts for oxygen reduction reaction in alkaline electrolyte, 178. Electrochim. Acta. 2015:179–189. doi: 10.1016/j.electacta.2015.07.181. - DOI
    1. Xian F., Gao L., Zhang Z., Zhang H., Dong S., Cui G. N, P dual-doped multi-wrinkled nanosheets prepared from the egg crude lecithin as the efficient metal-free electrocatalyst for oxygen reduction reaction. Appl. Surf. Sci. 2019;476:76–83. doi: 10.1016/j.apsusc.2018.12.293. - DOI
    1. Zhang J., Dai L. Nitrogen, phosphorus, and fluorine tri‐doped graphene as a multifunctional catalyst for self‐powered electrochemical water splitting. Angew. Chem. Int. Ed. 2016;128:13490–13494. doi: 10.1002/ange.201607405. - DOI - PubMed

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