Corrosion of monometallic iron- and nickel-based electrocatalysts for the alkaline oxygen evolution reaction: A review
TL;DR: In this paper, the authors review the corrosion of five types of monometallic Fe-and Ni-based OER catalysts: pure metals, oxides, (oxy)hydroxides, phosphides, and sulfides.
About: This article is published in Journal of Power Sources.The article was published on 2021-10-31. It has received 16 citations till now. The article focuses on the topics: Corrosion & Catalysis.
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26 Nov 2015
TL;DR: In this paper, the authors present a set of data files from CasaXPS, including the raw XPS raw data, Fe2p fit data and S2P fit data, along with the data calibrated to adventitious C1s.
Abstract: Contents of data folder: Electrochemical Data -> Electrochemical Data.xlsx Contains the electrochemical data obtained from IviumSoft used for Figures 3, 4, 5, 6, 7, 10, S5, S6, S7, S9, S13 and S17. Electrolysis GC Data -> Electrolyser GC Data.xlsx -> Electrolyser GC Data (Seawater).xlsx Contains integration data from Agilent GC software for H2 and O2 quantification and the calculations used to convert GC data into amounts of product. Elemental Abundance Price Data -> Elemental Cost-Abundance Data.xlsx Contains crustal abundance data of elements tabulated from P.A. Cox The Elements: Their Origin, Abundance, and Distribution and price data tabulated from the US Geological Survery Mineral Commodity Summaries. Used for Figure S1. Fe content UV-vis -> Fe content and calibration.xlsx Contains the UV-vis spectral data from Agilent software of absorption by Fe species dissolved in concentrated HCl. Both the calibration and spectra for the synthesised materials are shown. Also includes the calculation of converting UV-vis absorption to quantification of Fe content in electrodes. Used for Table S1 and Figure S14. SEM -> “Material Name” -> “as-prepared/HER/OER” .tiff Contains original SEM images as .tiff files for all the materials used in this work, as-prepared, after HER catalysis and after OER catalysis. Used for Figures 1, S8 and S16. XPS -> XPS_Raw_Data.vms -> XPS_C1s_Calibrated.vms -> XPS_Data_Fit.vms -> XPS Data File Information.rtf Contains the XPS raw data file from CasaXPS in original .vms along with the data calibrated to adventitious C1s and with peak fittings. The Data File Information contains further information about how to navigate the .vms files in CasaXPS. XPS -> Fe2p_Fit_TXT -> Raw_Data_TXT -> S2p_Fit_TXT Contains XPS raw data, Fe2p fit data and S2p fit data exported from CasaXPS as .txt files, used in Figures 2, 9, S3, S4, S10, S11 and S12. XRD -> XRD_Raw.xlsx Contains the raw XRD data from PANanalytical software used for Figures S2 and S15.
106 citations
01 Jan 2004
TL;DR: In this paper, angle-resolved x-ray photoelectron spectroscopy (ARXPS) and QUASES were used to determine the thickness of the oxide layer formed and its composition.
Abstract: Air oxidation of Fe was compared with and without a pre-exposure to water vapour. Angle-resolved x-ray photoelectron spectroscopy (ARXPS) and QUASES were used to determine the thickness of the oxide layer formed and its composition. The extent of oxidation was found to be much less if the surface was pre-exposed to water rather than air alone. Studies performed using ARXPS were able to show that the hydroxyl-containing layer located at the surface after Fe was exposed to water vapour was located below the surface after exposure to air. This observation suggested that the oxidation of Fe in air is mediated by cation diffusion. Copyright 2004 John Wiley & Sons, Ltd.
44 citations
TL;DR: In this paper, a nickel sulfide (NiS) nanowires are developed directly on nickel foam (NF), which have proven to be a highly efficient electrocatalyst for OER in an alkaline medium.
8 citations
TL;DR: In this paper , a nickel sulfide (NiS) nanowires are developed directly on nickel foam (NF), which have proven to be a highly efficient electrocatalyst for OER in an alkaline medium.
8 citations
TL;DR: In this paper , a Fe-doped amorphous CoOx (a-CoyFezOx) was used as an oxygen evolution reaction (OER) catalyst by a facile reduction reaction at room temperature.
Abstract: Reasonable optimization of the crystal structure and composite is an effective way to enhance the electrocatalytic activity of transition metal oxides. Herein, we report a strategy to fabricate Fe-doped amorphous CoOx (a-CoyFezOx) as an oxygen evolution reaction (OER) catalyst by a facile reduction reaction at room temperature. In a 1 M KOH electrolyte, the optimized a-Co2.5Fe0.5Ox catalyst shows the best OER activity. It only requires a 280 mV overpotential to achieve a current density of 10 mA cm–2 with a Tafel slope of 39.9 mV dec–1, which is even better than that of a commercial IrO2 catalyst. This high activity can be ascribed to the combined merits of the amorphous structure and the doped Fe element. The amorphous structure can enlarge the electrochemically accessible surface area and offer more active sites, while the Fe doped into the amorphous CoOx material can not only form the Fe site to promote the adsorption of intermediates during the OER process but also optimize the electronic structure of neighboring Co sites to enhance the OER activity. This work provides a strategy for rational design and large-scale synthesis of the transition metal oxide electrocatalysts to enhance the OER performance.
7 citations
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TL;DR: In this paper, the authors report a protocol for evaluating the activity, stability, and Faradaic efficiency of electrodeposited oxygen-evolving electrocatalysts for water oxidation.
Abstract: Objective evaluation of the activity of electrocatalysts for water oxidation is of fundamental importance for the development of promising energy conversion technologies including integrated solar water-splitting devices, water electrolyzers, and Li-air batteries. However, current methods employed to evaluate oxygen-evolving catalysts are not standardized, making it difficult to compare the activity and stability of these materials. We report a protocol for evaluating the activity, stability, and Faradaic efficiency of electrodeposited oxygen-evolving electrocatalysts. In particular, we focus on methods for determining electrochemically active surface area and measuring electrocatalytic activity and stability under conditions relevant to an integrated solar water-splitting device. Our primary figure of merit is the overpotential required to achieve a current density of 10 mA cm–2 per geometric area, approximately the current density expected for a 10% efficient solar-to-fuels conversion device. Utilizing ...
4,808 citations
TL;DR: Measurements of activity as a function of film thickness on Au and glassy carbon substrates are consistent with the hypothesis that Fe exerts a partial-charge-transfer activation effect on Ni, similar to that observed for noble-metal electrode surfaces.
Abstract: Fe plays a critical, but not yet understood, role in enhancing the activity of the Ni-based oxygen evolution reaction (OER) electrocatalysts. We report electrochemical, in situ electrical, photoelectron spectroscopy, and X-ray diffraction measurements on Ni1–xFex(OH)2/Ni1–xFexOOH thin films to investigate the changes in electronic properties, OER activity, and structure as a result of Fe inclusion. We developed a simple method for purification of KOH electrolyte that uses precipitated bulk Ni(OH)2 to absorb Fe impurities. Cyclic voltammetry on rigorously Fe-free Ni(OH)2/NiOOH reveals new Ni redox features and no significant OER current until >400 mV overpotential, different from previous reports which were likely affected by Fe impurities. We show through controlled crystallization that β-NiOOH is less active for OER than the disordered γ-NiOOH starting material and that previous reports of increased activity for β-NiOOH are due to incorporation of Fe-impurities during the crystallization process. Through...
2,419 citations
TL;DR: Observations suggest that the OER is catalyzed by Ni in Ni-Fe films and that the presence of Fe alters the redox properties of Ni, causing a positive shift in the potential at which Ni(OH)2/NiOOH redox occurs.
Abstract: A detailed investigation has been carried out of the structure and electrochemical activity of electrodeposited Ni-Fe films for the oxygen evolution reaction (OER) in alkaline electrolytes. Ni-Fe films with a bulk and surface composition of 40% Fe exhibit OER activities that are roughly 2 orders of magnitude higher than that of a freshly deposited Ni film and about 3 orders of magnitude higher than that of an Fe film. The freshly deposited Ni film increases in activity by as much as 20-fold during exposure to the electrolyte (KOH); however, all films containing Fe are stable as deposited. The oxidation of Ni(OH)2 to NiOOH in Ni films occurs at potentials below the onset of the OER. Incorporation of Fe into the film increases the potential at which Ni(OH)2/NiOOH redox occurs and decreases the average oxidation state of Ni in NiOOH. The Tafel slope (40 mV dec(-1)) and reaction order in OH(-) (1) for the mixed Ni-Fe films (containing up to 95% Fe) are the same as those for aged Ni films. In situ Raman spectra acquired in 0.1 M KOH at OER potentials show two bands characteristic of NiOOH. The relative intensities of these bands vary with Fe content, indicating a change in the local environment of Ni-O. Similar changes in the relative intensities of the bands and an increase in OER activity are observed when pure Ni films are aged. These observations suggest that the OER is catalyzed by Ni in Ni-Fe films and that the presence of Fe alters the redox properties of Ni, causing a positive shift in the potential at which Ni(OH)2/NiOOH redox occurs, a decrease in the average oxidation state of the Ni sites, and a concurrent increase in the activity of Ni cations for the OER.
1,951 citations
TL;DR: It is hypothesized that Fe is the most-active site in the catalyst, while CoOOH primarily provides a conductive, high-surface area, chemically stabilizing host.
Abstract: Cobalt oxides and (oxy)hydroxides have been widely studied as electrocatalysts for the oxygen evolution reaction (OER). For related Ni-based materials, the addition of Fe dramatically enhances OER activity. The role of Fe in Co-based materials is not well-documented. We show that the intrinsic OER activity of Co1–xFex(OOH) is ∼100-fold higher for x ≈ 0.6–0.7 than for x = 0 on a per-metal turnover frequency basis. Fe-free CoOOH absorbs Fe from electrolyte impurities if the electrolyte is not rigorously purified. Fe incorporation and increased activity correlate with an anodic shift in the nominally Co2+/3+ redox wave, indicating strong electronic interactions between the two elements and likely substitutional doping of Fe for Co. In situ electrical measurements show that Co1–xFex(OOH) is conductive under OER conditions (∼0.7–4 mS cm–1 at ∼300 mV overpotential), but that FeOOH is an insulator with measurable conductivity (2.2 × 10–2 mS cm–1) only at high overpotentials >400 mV. The apparent OER activity of ...
1,449 citations
TL;DR: In this paper, the Ni2P nanoparticles were used as both cathode and anode catalysts for an alkaline electrolyzer, which generated 10 mA cm−2 at 1.63 V.
Abstract: Electrochemical water splitting into hydrogen and oxygen is a promising method for solar energy storage. The development of efficient electrocatalysts for water splitting has drawn much attention. However, catalysts that are active for both the hydrogen evolution and oxygen evolution reactions are rare. Herein, we show for the first time that nickel phosphide (Ni2P), an excellent hydrogen evolving catalyst, is also highly active for oxygen evolution. A current density of 10 mA cm−2 is generated at an overpotential of only 290 mV in 1 M KOH. The high activity is attributed to the core–shell (Ni2P/NiOx) structure that the material adopts under catalytic conditions. The Ni2P nanoparticles can serve as both cathode and anode catalysts for an alkaline electrolyzer, which generates 10 mA cm−2 at 1.63 V.
1,374 citations