Catalysis of the Water Oxidation Reaction in the Presence of Iron and a Copper Foil

Akbari, Mohammad Saleh Ali; Najafpour, Mohammad Mahdi

doi:10.1021/acs.inorgchem.2c00448

Cited by 13 publications

(28 citation statements)

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“…The oxidation peak for the anodized electrode overlapped with the OER area. Based on previously published results, , these shifts correspond to increased Fe content in the anodized foam (Figure S1). Comparing Ni peaks for the fresh and anodizing foams shows that the amount of active material based on the Ni redox is significantly higher in the anodized electrode.…”

Section: Resultssupporting

confidence: 75%

“…Oxidation of nickel and its related redox features have been widely investigated. − The effect of anodization on the OER was investigated using chronoamperometry (CA) and cyclic voltammetry (CV), and the potential of 60 V was selected as the optimized potential to prepare the anodized electrode (Figure ). Anodization at higher potentials is not possible in our setup due to the potential electrical spark between the two electrodes and the increase in the temperature of the electrolyte.…”

Section: Resultsmentioning

confidence: 99%

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Anodization of a NiFe Foam: An Efficient and Stable Electrode for Oxygen-Evolution Reaction

Hashemi

Nandy

Chae

et al. 2022

ACS Appl. Energy Mater.

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Water splitting for hydrogen production is a promising method for storing sustainable energy sources. The oxygen-evolution reaction (OER) through water-oxidation reactions provides electrons for hydrogen production and is a limitation for water splitting. Thus, finding an efficient and stable OER catalyst is critical for water splitting. Herein, a NiFe foam, after harsh anodization at 60 V in a two-electrode system, is reported as an efficient and stable electrocatalyst. The NiFe oxide formed on the NiFe foam’s surface was characterized by some methods. These methods show the presence of different NiFe (hydr)oxides such as Ni(OH)2, NiO, and NiO(OH) on the surface of the NiFe foam. For the prepared electrode in the KOH solution (1.0 M), the overpotential for the onset of the OER is 220 mV. The overpotentials for the activities of 1, 10, and 100 mA/cm2 are observed at 290, 346, and 500 mV, respectively. A stable NiFe-oxide-based layer protects the bare foam from further oxidation, resulting in a stable electrocatalyst for the OER.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Anodization of a NiFe Foam: An Efficient and Stable Electrode for Oxygen-Evolution Reaction

Hashemi

Nandy

Chae

et al. 2022

ACS Appl. Energy Mater.

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“…This increase in the Ni/Fe ratio occurs because of the anodization process at high potential, which removes Fe ions. Other groups also reported that Fe removal on the electrode surface occurs during the OER. − …”

Section: Resultsmentioning

confidence: 99%

Dynamic Changes of an Anodized FeNi Alloy during the Oxygen Evolution Reaction under Alkaline Conditions

Akbari,

Nandy,

Chae

et al. 2023

Langmuir

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An efficient and durable oxygen evolution reaction (OER) catalyst is necessary for the water-splitting process toward energy conversion. The OER through water oxidation reactions could provide electrons for H 2 O, CO 2 , and N 2 reduction and produce valuable compounds. Herein, the FeNi (1:1 Ni/Fe) alloy as foam, after anodizing at 50 V in a two-electrode system in KOH solution (1.0 M), was characterized by Raman spectroscopy, diffuse reflectance spectroscopy (DRS), X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), high-angle annular darkfield imaging (HAADF)−scanning transmission electron microscopy (STEM) and used as an efficient and durable OER electrocatalyst in KOH solution (1.0 M). The overpotential for the onset of the OER based on extrapolation of the Tafel plot was 225 mV. The overpotentials for the current densities of 10 and 30 mA/cm 2 are observed at 270 and 290 mV, respectively. In addition, a low Tafel slope is observed, 38.0 mV per decade, for the OER. To investigate the mechanism of the OER, in situ surfaceenhanced Raman spectroscopy was used to detect FeNi hydroxide and characteristic peaks of H 2 O. Impurities in KOH can adsorb onto the electrode surface during the OER. Peaks corresponding to Ni(III) (hydr)oxide and FeO 4 2− can be detected during the OER, but high-valent FeNi (hydr)oxides are unstable and reduce under the open circle potential. Metal hydroxide transformations during the OER and anion adsorption should be carefully considered. In addition, Fe 3 O 4 may convert to γ-Fe 2 O 3 during the OER. This study aims to offer logical perspectives on the dynamic changes that occur during the OER under alkaline conditions in an anodized FeNi alloy. These changes encompass variations in morphology, surface oxidation, the generation of high-valent species, and phase conversion during the OER.

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“…Indeed, such changes in peaks are observed where Fe is removed from Fe/Ni (hydr)oxide. Especially at high anodization potentials, the oxidation of Fe to FeO 4 2– could result − in Fe depletion on the surface of the electrode (Figure c). On the other hand, after the anodization at 30–50 V, a new peak is observed at 1.30–1.35 V, which is related to Ni (hydr)oxide with small Fe content. − Such shifts in peaks are observed where Fe is removed from Fe/Ni (hydr)oxide.…”

Section: Resultsmentioning

confidence: 99%

NiFe Foam for Oxygen-Evolution Reaction under Neutral Conditions, Electrolysis of Baking Soda Solution: Catalytic and Mechanistic Studies

Maazallahi,

Bagheri,

Nandy

et al. 2023

ACS Appl. Energy Mater.

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NiFe oxide-based electrodes are promising compounds for oxygen-evolution reaction (OER), which is essential in metal–air batteries and water splitting. Indeed, OER is of great significance in the energy storage domain. Herein, NiFe oxide-based electrodes have been applied as effective and durable electrocatalysts in the presence of NaHCO3 (baking soda). Compared to corrosive acidic or alkaline solutions, the electrolysis of the baking soda solution toward producing oxygen and hydrogen is highly promising. Surprisingly, NiFe foam, without any anodization or modification, is an efficient and stable electrode for OER at pH= 8.5 (NaHCO3, 0.75 M). In addition, the experiments show that NiO(OH) and not Ni (bicarbonate) is the true catalyst for OER. The surface of the foam was investigated through several methods, including in situ Raman spectroscopy in the presence of NaH12/13CO3. All of the methods indicate the presence of various NiFe (hydr)oxides with different phases on the NiFe foam’s surface. For the NiFe foam at pH= 8.5 (NaHCO3, 0.75 M), the overpotentials for the onset of OER and the activity at 10 mA/cm2 are recorded at 250 and 460 mV, respectively. The Tafel plot of the electrode prepared at pH = 8.5 shows the linearity of the log(i) vs overpotential with a slope as low as 60 mV per decade. The effects of anodization potentials, electrochemically active surface areas, and a proposed mechanism for OER are also discussed. At least one possible pathway for OER could be the reaction of the electrolyte with high valent Ni ions on the surface of the electrode.

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Catalysis of the Water Oxidation Reaction in the Presence of Iron and a Copper Foil

Cited by 13 publications

References 50 publications

Anodization of a NiFe Foam: An Efficient and Stable Electrode for Oxygen-Evolution Reaction

Anodization of a NiFe Foam: An Efficient and Stable Electrode for Oxygen-Evolution Reaction

Dynamic Changes of an Anodized FeNi Alloy during the Oxygen Evolution Reaction under Alkaline Conditions

NiFe Foam for Oxygen-Evolution Reaction under Neutral Conditions, Electrolysis of Baking Soda Solution: Catalytic and Mechanistic Studies

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