Investigation of the stability of NiFe-(oxy)hydroxide anodes in alkaline water electrolysis under industrially relevant conditions

Pascuzzi, Marco Etzi Coller; Man, Alex Jan Wai; Goryachev, Andrey; Hofmann, Jan P.; Hensen, Emiel J. M.

doi:10.1039/d0cy01179g

Cited by 41 publications

(31 citation statements)

References 59 publications

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“…One strategy to reduce Fe leaching may be to incorporate it within the catalysts’ bulk structures. However, the preferential leaching of Fe compared to Ni under highly basic conditions and elevated temperatures in such devices will have to be addressed. , Improved stability might be achieved through novel synthesis methods and taking advantage of the catalyst/support interactions . The MEA configuration, though, might help to prevent the loss of dissolved species and favor their redeposition at the anode, while a more-selective AEM will slow the crossover of the those species to the cathode .…”

Section: Toward Advanced Electrolysis: Ni- and Co-based Catalysts Wit...mentioning

confidence: 99%

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Krivina

et al. 2021

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Catalyzing the oxygen evolution reaction (OER) is important for key energy-storage technologies, particularly water electrolysis and photoelectrolysis for hydrogen fuel production. Under neutral-to-alkaline conditions, first-row transitionmetal oxides/(oxy)hydroxides are the fastest-known OER catalysts and have been the subject of intense study for the past decade. Critical to their high performance is the intentional or accidental addition of Fe to Ni/Co oxides that convert to layered (oxy)hydroxide structures during the OER. Unraveling the role that Fe plays in the catalysis and the molecular identity of the true "active site" has proved challenging, however, due to the dynamics of the host structure and absorbed Fe sites as well as the diversity of local structures in these disordered active phases.In this Account, we highlight our work to understand the role of Fe in Ni/Co (oxy)hydroxide OER catalysts. We first discuss how we characterize the intrinsic activity of the first-row transition-metal (oxy)hydroxide catalysts as thin films by accounting for the contributions of the catalyst-layer thickness (mass loading) and electrical conductivity as well as the underlying substrate's chemical interactions with the catalyst and the presence of Fe species in the electrolyte. We show how Fe-doped Ni/Co (oxy)hydroxides restructure during catalysis, absorb/desorb Fe, and in some cases degrade or regenerate their activity during electrochemical testing. We highlight the relevant techniques and procedures that allowed us to better understand the role of Fe in activating other first-row transition metals for OER. We find several modes of Fe incorporation in Ni/Co (oxy)hydroxides and show how those modes correlate with activity and durability. We also discuss how this understanding informs the incorporation of earthabundant transition-metal OER catalysts in anion-exchange-membrane water electrolyzers (AEMWE) that provide a locally basic anode environment but run on pure water and have advantages over the more-developed proton-exchange-membrane water electrolyzers (PEMWE) that use platinum-group-metal (PGM) catalysts. We outline the key issues of introducing Fe-doped Ni/Co (oxy)hydroxide catalysts at the anode of the AEMWE, such as the oxidative processes triggered by Fe species traveling through the polymer membrane, pH-gradient effects on the catalyst stability, and possibly limited catalyst utilization in the compressed stack configuration. We also suggest possible mitigation strategies for these issues. Finally, we summarize remaining challenges including the long-term stability of Fe-doped Ni/Co (oxy)hydroxides under OER conditions and the lack of accurate models of the dynamic active surface that hinder our understanding of, and thus ability to design, these catalysts.

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Section: Toward Advanced Electrolysis: Ni- and Co-based Catalysts Wit...mentioning

confidence: 99%

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Krivina

et al. 2021

Acc. Mater. Res.

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“…Although significant effort has been devoted to developing highly active NiFe-based OER electrocatalysts, few studies have focused on this topic, − which is also important for practical water splitting. Recent studies have shown that the OER degradation is a common issue among the NiFe-based electrocatalysts under prolonged OER conditions, but the causes are still not fully understood. ,,, For example, Speck et al found that Fe in the FeNiO x films (anode), which were synthesized via electrodeposition or near-infrared-driven decomposition, leached into the KOH electrolyte and deposited on the Ni-cathode during the OER, which is likely related to the OER degradation, especially at high current densities . Obata and Takanabe also observed the loss of Fe from electrodeposited NiFeO x films (on an Au-coated FTO substrate) into the KOH electrolyte during the OER, which resulted in gradual OER deactivation over time .…”

Section: Introductionmentioning

confidence: 99%

Host, Suppressor, and Promoter—The Roles of Ni and Fe on Oxygen Evolution Reaction Activity and Stability of NiFe Alloy Thin Films in Alkaline Media

et al. 2021

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Understanding the oxygen evolution reaction (OER) activity and stability of the NiFe-based materials is important for achieving low-cost and highly efficient electrocatalysts for practical water splitting. Here, we report the roles of Ni and Fe on the OER activity and stability of metallic NiFe and pure Ni thin films in alkaline media. Our results support that Ni(OH) 2 /NiOOH does not contribute to the OER directly, but it serves as an ideal host for Fe incorporation, which is essential for obtaining high OER activity. Furthermore, the availability of Fe in the electrolyte is found to be important and necessary for both NiFe and pure Ni thin films to maintain an enhanced OER performance, while the presence of Ni is detrimental to the OER kinetics. The impacts of Fe and Ni species present in KOH on the OER activity are consistent with the dissolution/re-deposition mechanism we proposed. Stability studies show that the OER activity will degrade under prolonged continuous operation. Satisfactory stability can, however, be achieved with intermittent OER operation, in which the electrocatalyst is cycled between degraded and recovered states. Accordingly, two important ranges, that is, the recovery range and the degradation range, are proposed. Compared to the intermittent OER operation, prolonged continuous OER operation (i.e., in the degradation range) generates a higher NiOOH content in the electrocatalyst, which is likely related to the OER deactivation. If the electrode works in the recovery range for a certain period, that is, at a sufficiently low reduction potential, where Ni 3+ is reduced to Ni 2+ , the OER activity can be maintained and even improved if Fe is also present in the electrolyte.

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“…3 One class of materials that has received significant interest over the past years are mixed metal oxides of nickel and iron ((Ni,Fe)O x ), as they show remarkable catalytic activity for the oxygen evolution reaction, are sourced from Earth-abundant metals, and are (for the most part) stable under reaction conditions. 4,5 (Ni,Fe)O x catalyst occur in a variety of configurations. NiFe layered double hydroxides (LDHs) have been shown to be highly efficient for OER applications.…”

Section: Introductionmentioning

confidence: 99%

Local structural changes in polyamorphous (Ni,Fe)O_x electrocatalysts suggest a dual-site oxygen evolution reaction mechanism

et al. 2021

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Investigation of the stability of NiFe-(oxy)hydroxide anodes in alkaline water electrolysis under industrially relevant conditions

Abstract: NiFe-(oxy)hydroxide is one of the most active electrocatalysts for the oxygen evolution reaction (OER) in alkaline conditions. Herein we investigated the stability of NiFe-(oxy)hydroxide anodes at high current densities (100...

Cited by 41 publications

References 59 publications

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Host, Suppressor, and Promoter—The Roles of Ni and Fe on Oxygen Evolution Reaction Activity and Stability of NiFe Alloy Thin Films in Alkaline Media

Local structural changes in polyamorphous (Ni,Fe)O_x electrocatalysts suggest a dual-site oxygen evolution reaction mechanism

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Investigation of the stability of NiFe-(oxy)hydroxide anodes in alkaline water electrolysis under industrially relevant conditions

Abstract: NiFe-(oxy)hydroxide is one of the most active electrocatalysts for the oxygen evolution reaction (OER) in alkaline conditions. Herein we investigated the stability of NiFe-(oxy)hydroxide anodes at high current densities (100...

Cited by 41 publications

References 59 publications

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Oxygen Electrocatalysis on Mixed-Metal Oxides/Oxyhydroxides: From Fundamentals to Membrane Electrolyzer Technology

Host, Suppressor, and Promoter—The Roles of Ni and Fe on Oxygen Evolution Reaction Activity and Stability of NiFe Alloy Thin Films in Alkaline Media

Local structural changes in polyamorphous (Ni,Fe)Ox electrocatalysts suggest a dual-site oxygen evolution reaction mechanism

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Local structural changes in polyamorphous (Ni,Fe)O_x electrocatalysts suggest a dual-site oxygen evolution reaction mechanism