Reduction of magnetite to metallic iron in strong alkaline medium

Monteiro, J.F.; Ivanova, Yu. A.; Kovalevsky, Andrei V.; Ivanou, Dzmitry; Frade, J.R.

doi:10.1016/j.electacta.2016.02.058

Cited by 41 publications

(56 citation statements)

References 27 publications

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“…Moreover, with respect to the anodic polarization of the iron electrode, also even more than just two oxidation peaks have been reported by several researchers [203,215,225]. Haupt et al, for example, reported the observation of four rather than two oxidation peaks for an iron sheet in 1M NaOH at about −0.80 V, −0.60 V, −0.45 V and −0.20 V vs. SHE.…”

Section: Iron-air Batteriesmentioning

confidence: 90%

Silicon and Iron as Resource-Efficient Anode Materials for Ambient-Temperature Metal-Air Batteries: A Review

et al. 2019

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Metal-air batteries provide a most promising battery technology given their outstanding potential energy densities, which are desirable for both stationary and mobile applications in a “beyond lithium-ion” battery market. Silicon- and iron-air batteries underwent less research and development compared to lithium- and zinc-air batteries. Nevertheless, in the recent past, the two also-ran battery systems made considerable progress and attracted rising research interest due to the excellent resource-efficiency of silicon and iron. Silicon and iron are among the top five of the most abundant elements in the Earth’s crust, which ensures almost infinite material supply of the anode materials, even for large scale applications. Furthermore, primary silicon-air batteries are set to provide one of the highest energy densities among all types of batteries, while iron-air batteries are frequently considered as a highly rechargeable system with decent performance characteristics. Considering fundamental aspects for the anode materials, i.e., the metal electrodes, in this review we will first outline the challenges, which explicitly apply to silicon- and iron-air batteries and prevented them from a broad implementation so far. Afterwards, we provide an extensive literature survey regarding state-of-the-art experimental approaches, which are set to resolve the aforementioned challenges and might enable the introduction of silicon- and iron-air batteries into the battery market in the future.

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Section: Iron-air Batteriesmentioning

confidence: 90%

Silicon and Iron as Resource-Efficient Anode Materials for Ambient-Temperature Metal-Air Batteries: A Review

et al. 2019

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“…Monteiro et al 37 studied magnetite reduction in a strong alkaline electrolyte and indicated that there is a gradual development of porosity at the magnetite/bulk electrolyte interface. Thus, as the oxide is reduced the product, being either a Fe(II) oxide or Fe 2+ ion would result in a lower porosity.…”

Section: Discussionmentioning

confidence: 99%

Editors' Choice—A Methodology to Electrochemically Fabricate Fe-Ni-Co Nanotips

Geng¹,

Liang²,

Podlaha³

2017

J. Electrochem. Soc.

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Fe-Ni-Co nanotips at the end of nanowires are fabricated at the interface of two Fe-Ni-Co regions via a combination of pulse electrodeposition, anodization and chemical etching. The conditions to electrodeposit and anodize the Fe-Ni-Co nanowires in polycarbonate templates were investigated with a rotating cylinder electrode (RCE) to inspect the polarization behavior of the thin film deposition. The wires were fabricated with three, consecutive electrochemical conditions, where first an Fe-Ni-Co wire segment is deposited, followed by an anodic potential to induce growth of an iron oxide thin film, and then followed by an applied, pulse cathodic current density to reduce the oxide and deposit another layer of Fe-Ni-Co. Upon etching, tips formed at the end of the last Fe-Ni-Co region, as evidenced by SEM. Potential transients during the last applied cathodic pulse current step, suggests that both the reduction of the oxide and metal occur, and that TEM/SAED confirm changes in the crystalline Fe-Ni-Co structure at the interfacial region between steps that contributes to the tip formation. Electrodeposition conditions to fabricate nanowires using nanoporous templates have been widely examined for different applications, and several good reviews summarize the vast number of metal and alloy nanowire systems considered.1-4 Different nanowire morphologies have been reported, some directly formed within the templates, such as nanotubes, [5][6][7] and those that are subsequently etched once released from their templates, such as nanogaps, 4,8 and porous nanowires, 9,10 or through subsequent annealing or displacement reactions resulting in interesting structures, such as nanopeapods. 11,12In addition, Geng and Podlaha 13 recently, showed that Cu-Fe-Ni-Co nanowires could be etched in a preferred radial direction, thinning nanowire segments.Nanowires that are shaped into tips at one end, nanotips, have been widely researched due to their application as cantilever tips for high-resolution atomic force microscopy (AFM), 14,15 tip-enhanced near-field optical microscopy, 16 and scanning tunneling microscopy (STM), [17][18][19] and the need has recently expanded to bio/chemical sensors to measure electrical conduction as a new methodology for molecular detection and monitoring. [20][21][22][23] The reported nanotip materials used in AFM/STM are usually W and Pt/Ir, which are prepared through a "drop off" technique, where the tungsten wire is immersed in a KOH solution (etchant) acting as an anodic electrode; the highest etching rate appears just below the air/electrolyte interface, causing necking and eventual "drop off" of the bottom part of the wire, leaving a sharp tip. 14,17,19,24,25 Alternative methods for fabricating nanotips include: focused ion beam (FIB) lithography, 26 vapor-liquidsolid method (VLS), 27,28 and a novel, self-masking technique where SiC nanosized clusters are generated on top of a substrate, followed by a dry etch of the unmasked substrate regions to create nanotips where the SiC clusters reside. 29In this...

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“…1a), two distinct peaks III and IV were observed, representing a complex transformation of Fe III → Fe II → Fe 0 (Eqs. 7-10) [23,24]. At potentials close to E = − 1500 mV, hydrogen evolution occurs according to Eq.…”

Section: Resultsmentioning

confidence: 99%

Oxide nanolayer formation on surface of modified blast furnace sludge particles during voltammetric cycling in alkaline media

Novák

Kostura

Raška

et al. 2020

J Solid State Electrochem

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Knowledge of the properties of metallurgical waste is essential for the assessment of their recycling. In this work, the formation of iron oxide nanolayers during voltammetric cycling in 1 M NaOH on the particle surface of blast furnace sludge after acid leaching (BFSL) was studied. Most importantly, the effect of hydrogen on these processes was of particular interest. For these purposes, the study combines electrochemical methods, cyclic voltammetry on solid and carbon paste electrodes, with analytical optical methods (TEM). On the solid iron electrode surface as a model system, nanostructured magnetite (Fe 3 O 4 ) was identified as the main oxidation product, and, to a lesser extent, also maghemite (γ-Fe 2 0 3 ). It was found that the charges corresponding to Fe 3 O 4 formation and its reduction together with the hydrogen evolution reaction (HER) occurring at E = − 1500 mV depend on the number of cycles and have a similar course. Additionally, in the first phase of the cycling, the accumulation of maghemite on the solid Fe-electrode surface during cycling affects the growth of the oxide layer and catalytically increases the yield of the HER. Concerning the measurement with BFSL-modified CPE, on the BFSL surface, haematite is transformed into magnetite during cycling, resulting in the same Fe 3 O 4 nanolayer as on the solid iron electrode. In this layer, the same redox processes take place, including the influence of hydrogen in the initial stage of cycling.

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Reduction of magnetite to metallic iron in strong alkaline medium

Cited by 41 publications

References 27 publications

Silicon and Iron as Resource-Efficient Anode Materials for Ambient-Temperature Metal-Air Batteries: A Review

Silicon and Iron as Resource-Efficient Anode Materials for Ambient-Temperature Metal-Air Batteries: A Review

Editors' Choice—A Methodology to Electrochemically Fabricate Fe-Ni-Co Nanotips

Oxide nanolayer formation on surface of modified blast furnace sludge particles during voltammetric cycling in alkaline media

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