Oxygen evolution anodes composed of anodically deposited Mn–Mo–Fe oxides for seawater electrolysis

Ghany, Nabil A. Abdel; Kumagai, Naokazu; Meguro, Shinsaku; Asami, K.; Hashimoto, Kôji

doi:10.1016/s0013-4686(02)00539-x

Cited by 102 publications

(24 citation statements)

References 21 publications

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“…A notable exception is manganese oxide (MnO x ), an OER-active material that has received significant interest in recent years. − Initially reported by Bennet, anodes based on MnO x show a strong tendency to selectively evolve oxygen from acidic saline water. Hashimoto et al studied a series of Mn-based mixed metal oxides (MMO) deposited on an IrO x /Ti substrate and showed that such anodes often exhibit nearly 100% selectivity toward OER, under a variety of experimental conditions, for many hours of sustained operation. − Besides its high reported OER selectivity, MnO x is also one of the few nonprecious metal-based catalysts that has been reported to be moderately stable in acid under OER conditions . This stability is in strong contrast with other 3d metal oxides such as CoO x and Ni/Fe-based oxyhydroxides, materials that show very high OER activity in alkaline pH, but are unstable and inactive in acid. ,− …”

Section: Introductionmentioning

confidence: 99%

MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

et al. 2018

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The oxygen evolution reaction (OER) and chlorine evolution reaction (CER) are electrochemical processes with high relevance to water splitting for (solar) energy conversion and industrial production of commodity chemicals, respectively. Carrying out the two reactions separately is challenging, since the catalytic intermediates are linked by scaling relations. Optimizing the efficiency of OER over CER in acidic media has proven especially difficult. In this regard, we have investigated the OER versus CER selectivity of manganese oxide (MnOx), a known OER catalyst. Thin films (∼5–20 nm) of MnOx were electrodeposited on glassy carbon-supported hydrous iridium oxide (IrOx/GC) in aqueous chloride solutions of pH ∼0.9. Using rotating ring–disk electrode voltammetry and online electrochemical mass spectrometry, it was found that deposition of MnOx onto IrOx decreases the CER selectivity of the system in the presence of 30 mM Cl– from 86% to less than 7%, making it a highly OER-selective catalyst. Detailed studies of the CER mechanism and ex-situ structure studies using SEM, TEM, and XPS suggest that the MnOx film is in fact not a catalytically active phase, but functions as a permeable overlayer that disfavors the transport of chloride ions.

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Section: Introductionmentioning

confidence: 99%

MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

et al. 2018

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“…The, they modified manganese-based electrode materials and gained high oxygen efficiencies while testing their catalyst in 0.5 M NaCl at pH 8. However, in later work they focused on selective OER at pH 1, but similarly to Bennett, Hashimoto and co-workers choose comparably low current densities of 1 mA cm –2 . − At higher currents of 100 mA cm –2 , El-Monheim tested an electrode made of Mn–Mo–W, which was electrochemically deposited on a Ti/IrO 2 net . Using a two-compartment electrochemical cell equipped with a three-electrode setup, this electrode was analyzed for up to 3500 h in a 0.5 M NaCl solution at pH 8.7.…”

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confidence: 99%

Direct Electrolytic Splitting of Seawater: Opportunities and Challenges

et al. 2019

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Hot, coastal, hyper-arid regions with intense solar irradiation and strong on- and off-shore wind patterns are ideal locations for the production of renewable electricity using wind turbines or photovoltaics. Given ample access to seawater and scarce freshwater resources, such regions make the direct and selective electrolytic splitting of seawater into molecular hydrogen and oxygen a potentially attractive technology. The key catalytic challenge consists of the competition between anodic chlorine chemistry and the oxygen evolution reaction (OER). This Perspective addresses some aspects related to direct seawater electrolyzers equipped with selective OER and hydrogen evolution reaction (HER) electrocatalysts. Starting from a historical background to the most recent achievements, it will provide insights into the current state and future perspectives of the topic. This Perspective also addresses prospects of the combination of direct seawater electrolysis with hydrogen fuel cell technology (reversible seawater electrolysis) and discusses its suitability as combined energy conversion–freshwater production technology.

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“…All ∆E i -i plots show straight lines. Thus, we can estimate the resistance difference of two oxide anodes from ∂(∆E i )/∂i = r-r 30 min (11) All potential differences, ∂(∆E i )/∂i, are positive. The activity is determined by the composition of the top-most surface, and the compositions of the top-most surfaces of the three deposits formed by deposition for final 30 min from the fresh solution are not different.…”

Section: Resultsmentioning

confidence: 99%

“…The addition of Mo 6+ [4,6] and/or W 6+ [7] was effective, showing the 100 % oxygen evolution efficiency. Formation of triple oxides, such as Mn-Mo-W oxides [8][9][10], Mn-Mo-Fe oxides [11,12] and Mn-Mo-Sn oxides [13,14] were particularly effective for extension of the lifetime of the anode. The electrocatalysts with Mo, W, Fe and/or Sn were all identified as a single phase multiple oxides of γ-MnO 2 structure, without forming any second oxide phase, and were stable without suffering from oxidative dissolution in the form of MnO 4 in spite of the polarization potential far higher than the oxidation potential of MnO 2 to MnO 4…”

Section: Introductionmentioning

confidence: 99%

Novel Anode Materials for Oxygen Evolution during Seawater Electrolysis for Green Hydrogen Fuel Production

El‐Moneim¹

2011

IJTEE

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Mn 1-x-y Mo x W y O 2+x+y triple oxide electrocatalysts for the anode producing oxygen without forming chlorine in seawater electrolysis were prepared by anodic deposition. The performance of the anode for oxygen evolution in 0.5 M NaCl solutions was examined. The tungsten addition was effective in extending the life of the anode by decreasing the density of pores in electrocatalysts responsible for partial detachment of electrocatalysts, which occurs by high pressure of oxygen formed preferentially at the bottom of pores during electrolysis. Repeated anodic deposition of the electrocatalyst significantly extended the life of the anode, because repeated deposition was able to cover the pores in the underlying electrocatalysts. The potential observed in anodic polarization of an oxide electrode was the sum of the overpotential of the electrochemical reaction and the potential drop as a result of passage of current through the oxide. The potential difference of the two anodes at individual current, E i , versus the current, i, should show the straight line: The gradient, E i /i, is the difference of the electrical resistances of the two electrodes, and the activity of the two anodes can be compared from the current, i, at E i = 0 volt. The tungsten addition enhanced the activity for oxygen evolution.

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Oxygen evolution anodes composed of anodically deposited Mn–Mo–Fe oxides for seawater electrolysis

Cited by 102 publications

References 21 publications

MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

Direct Electrolytic Splitting of Seawater: Opportunities and Challenges

Novel Anode Materials for Oxygen Evolution during Seawater Electrolysis for Green Hydrogen Fuel Production

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Oxygen evolution anodes composed of anodically deposited Mn–Mo–Fe oxides for seawater electrolysis

Cited by 102 publications

References 21 publications

MnOx/IrOx as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

MnOx/IrOx as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

Direct Electrolytic Splitting of Seawater: Opportunities and Challenges

Novel Anode Materials for Oxygen Evolution during Seawater Electrolysis for Green Hydrogen Fuel Production

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Product

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MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

MnO_x/IrO_x as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution