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. 2024 Mar 8;29(6):1215.
doi: 10.3390/molecules29061215.

Modified NiFe2O4-Supported Graphene Oxide for Effective Urea Electrochemical Oxidation and Water Splitting Applications

Fowzia S Alamro  1 , Shymaa S Medany  2 , Nada S Al-Kadhi  1 , Hoda A Ahmed  2   3 , Mahmoud A Hefnawy  2
Affiliations

Modified NiFe2O4-Supported Graphene Oxide for Effective Urea Electrochemical Oxidation and Water Splitting Applications

Fowzia S Alamro et al. Molecules. .

Abstract

The production of green hydrogen using water electrolysis is widely regarded as one of the most promising technologies. On the other hand, the oxygen evolution reaction (OER) is thermodynamically unfavorable and needs significant overpotential to proceed at a sufficient rate. Here, we outline important structural and chemical factors that affect how well a representative nickel ferrite-modified graphene oxide electrocatalyst performs in efficient water splitting applications. The activities of the modified pristine and graphene oxide-supported nickel ferrite were thoroughly characterized in terms of their structural, morphological, and electrochemical properties. This research shows that the NiFe2O4@GO electrode has an impact on both the urea oxidation reaction (UOR) and water splitting applications. NiFe2O4@GO was observed to have a current density of 26.6 mA cm-2 in 1.0 M urea and 1.0 M KOH at a scan rate of 20 mV s-1. The Tafel slope provided for UOR was 39 mV dec-1, whereas the GC/NiFe2O4@GO electrode reached a current of 10 mA cm-2 at potentials of +1.5 and -0.21 V (vs. RHE) for the OER and hydrogen evolution reaction (HER), respectively. Furthermore, charge transfer resistances were estimated for OER and HER as 133 and 347 Ω cm2, respectively.

Keywords: fuel cells; graphene oxide; nickel ferrite; urea electrooxidation; water splitting.

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Conflict of interest statement

The authors declare that there are no conflicts of interest regarding the publication of this paper.

Figures

Figure 1
Figure 1
Representation of XRD of NiF2O4@GO. The * represents the peaks in reference card that reported in the manuscript (JCPDS card No. 54-0964).
Figure 2
Figure 2
Representation of XPS fitting data of (a) Ni2p, (b) Fe2p, (c) O1s, and (d) C1s.
Figure 3
Figure 3
(a) SEM and (b) TEM of GC/NiFe2O4@GO sample and corresponding its (c–h) surface mapping, and (i) EDAX.
Figure 3
Figure 3
(a) SEM and (b) TEM of GC/NiFe2O4@GO sample and corresponding its (c–h) surface mapping, and (i) EDAX.
Figure 4
Figure 4
CVs of the different modified electrodes in 1.0 M urea + 1.0 M KOH at 20 mV s−1.
Figure 5
Figure 5
CVs of (a) GC/NIO, (b) GC/NiFe2O4, and (c) GC/NiFe2O4@GO at a range of urea concentrations (0.05 to 1.0 M). (d) Linear relationship between urea concentration and anodic oxidation current.
Figure 6
Figure 6
CVs of (a) GC/NIO, (b) GC/NiFe2O4, and (c) GC/NiFe2O4@GO at a wide range of scan rates (5 to 200 mV s−1) in a solution of 1.0 M urea + 1.0 M KOH. (d) Linear relationship between the square root of the scan rate and anodic oxidation current.
Figure 7
Figure 7
CVs of (a) GC/NIO, (b) GC/NiFe2O4, and (c) GC/NiFe2O4@GO in 1.0 M KOH at a wide scan range. (d) Linear relationship between scan rate vs. anodic and cathodic currents.
Figure 8
Figure 8
Chronoamperogram of different modified surfaces for urea electrooxidation.
Figure 9
Figure 9
(a) Tafel Plot of the modified surfaces. (b) Nyquist plot of the modified electrode in 1.0 M urea and 1.0 M KOH, inset figure shows the fitting circuits.
Figure 10
Figure 10
(a) Linear sweep voltammetry of the oxygen evolution reaction for the different modified electrodes. (b) Tafel slopes of the OER for different surfaces.
Figure 11
Figure 11
(a) Linear sweep voltammetry of the hydrogen evolution reaction for different modified electrodes. (b) Tafel slopes of the HER for different surfaces.
Figure 12
Figure 12
Nyquist plots of the modified GC/ NiFe2O4@GO electrode for (a) OER and (b) HER.
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