Structure and transformation of oxy-hydroxide films on Ni anodes below and above the oxygen evolution potential in alkaline electrolytes

Mellsop, Sophia R.; Gardiner, Alister; Johannessen, Bernt; Marshall, A.

doi:10.1016/j.electacta.2015.04.020

Cited by 48 publications

(61 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…cyclic voltammetry), a change in the oxide structure is known to occur [1,8,24]. Here the cyclic voltammogram after 200 cycles is noticeably different to that after only 5 cycles (Figure 2).…”

Section: Galvanostatic Ageing and Rejuvenationmentioning

confidence: 92%

“…For example, raman spectroscopy suggests that at the onset of oxygen evolution, NiOOH transforms to another phase [15] and similarly our cyclic voltammetry work suggested that after extensive oxygen evolution (at least 40 hours at 50 mA cm -2 ) an additional phase forms [8]. Many authors have also suggested that over-oxidation causes Ni(IV) to form [6,[20][21][22][23], although there is currently little direct evidence of the formation of NiO 2 or other Ni(IV) species.…”

Section: Introductionmentioning

confidence: 94%

“…The true map of phases and their transformations is likely to be more complex [8] based on recent research [8,[14][15][16][17][18][19]. For example, raman spectroscopy suggests that at the onset of oxygen evolution, NiOOH transforms to another phase [15] and similarly our cyclic voltammetry work suggested that after extensive oxygen evolution (at least 40 hours at 50 mA cm -2 ) an additional phase forms [8].…”

Section: Introductionmentioning

confidence: 96%

“…Here the cyclic voltammogram after 200 cycles is noticeably different to that after only 5 cycles (Figure 2). It is well known that this cycling causes a transition from the α-Ni(OH) 2 / γ-NiOOH solid-state redox couple to the β-Ni(OH) 2 / β-NiOOH couple [1,8,24].…”

Section: Galvanostatic Ageing and Rejuvenationmentioning

confidence: 99%

“…Important factors to consider when choosing an electrocatalyst include its stability, performance, and cost. Many researchers have investigated nickel oxides as the electrocatalyst for the anodic oxygen evolution reaction [1][2][3][4][5][6][7], as it is much less costly than options such as iridium or ruthenium oxide and has reasonably good performance, with a potentials of approximately 750 mV vs. HgHgO at a current density of 50 mA cm -2 [8], and Tafel slopes as low as 38 mV. However, the performance stability under anodic conditions can be an issue, resulting in the performance of the electrocatalyst decreasing over time [6,8] As the loss in performance of nickel oxide anodes is generally accepted to be related to structural changes in the oxide, much of the research into nickel oxide electrocatalysts has involved investigating the structure of the electrocatalyst [6,[9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Electrocatalytic oxygen evolution on nickel oxy-hydroxide anodes: Improvement through rejuvenation

Mellsop

Gardiner

Marshall

2015

Electrochimica Acta

Self Cite

View full text Add to dashboard Cite

The ageing and rejuvenation behaviour of nickel oxy-hydroxide anodes for alkaline water electrolysis is investigated. The anodically formed oxy-hydroxide material is known to age over time causing a decrease in performance. However, this deactivation can be mitigated by temporarily reducing the potential for brief periods. This work looks at continuous rejuvenation of nickel anodes in 30wt.% KOH solution and it is shown that rejuvenation at 0.5 V vs. HgHgO for 10 minutes every 100 minutes can prevent ageing of the anode, thus maintaining a low overpotential during galvanostatic oxygen evolution at 50 mA cm -2 . It is suggested that the short potentiostatic rejuvenation periods at regular intervals prevents the ratio of Ni(IV) to Ni(III) from increasing, thereby maintaining the intrinsic activity of the material. The rejuvenation potential must be above 0.36 V vs. HgHgO to ensure it is effective in obtaining good performance (i.e. the material must not reduce to Ni(II)). These findings suggest that electrolysis systems using nickel anodes could benefit from direct coupling to fluctuating power sources such as solar or wind, where the variability in their power output could facilitate the rejuvenation of the nickel anode. We estimate that by using the rejuvenation steps, an energy saving of 9% is possible in an alkaline water electrolyser using nickel anodes.

show abstract

Section: Galvanostatic Ageing and Rejuvenationmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 96%

Section: Galvanostatic Ageing and Rejuvenationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrocatalytic oxygen evolution on nickel oxy-hydroxide anodes: Improvement through rejuvenation

Mellsop

Gardiner

Marshall

2015

Electrochimica Acta

Self Cite

View full text Add to dashboard Cite

show abstract

Transition‐Metal (Co, Ni, and Fe)‐Based Electrocatalysts for the Water Oxidation Reaction

2016

View full text Add to dashboard Cite

Increasing energy demands and environment awareness have promoted extensive research on the development of alternative energy conversion and storage technologies with high efficiency and environmental friendliness. Among them, water splitting is very appealing, and is receiving more and more attention. The critical challenge of this renewable-energy technology is to expedite the oxygen evolution reaction (OER) because of its slow kinetics and large overpotential. Therefore, developing efficient electrocatalysts with high catalytic activities is of great importance for high-performance water splitting. In the past few years, much effort has been devoted to the development of alternative OER electrocatalysts based on transition-metal elements that are low-cost, highly efficient, and have excellent stability. Here, recent progress on the design, synthesis, and application of OER electrocatalysts based on transition-metal elements, including Co, Ni, and Fe, is summarized, and some invigorating perspectives on the future developments are provided.

show abstract

In Situ Formation of Nano Ni–Co Oxyhydroxide Enables Water Oxidation Electrocatalysts Durable at High Current Densities

et al. 2021

View full text Add to dashboard Cite

The oxygen evolution reaction (OER) limits the energy efficiency of electrocatalytic systems due to the high overpotential symptomatic of poor reaction kinetics; this problem worsens over time if the performance of the OER electrocatalyst diminishes during operation. Here, a novel synthesis of nanocrystalline Ni–Co–Se using ball milling at cryogenic temperature is reported. It is discovered that, by anodizing the Ni–Co–Se structure during OER, Se ions leach out of the original structure, allowing water molecules to hydrate Ni and Co defective sites, and the nanoparticles to evolve into an active Ni–Co oxyhydroxide. This transformation is observed using operando X‐ray absorption spectroscopy, with the findings confirmed using density functional theory calculations. The resulting electrocatalyst exhibits an overpotential of 279 mV at 0.5 A cm−2 and 329 mV at 1 A cm−2 and sustained performance for 500 h. This is achieved using low mass loadings (0.36 mg cm−2) of cobalt. Incorporating the electrocatalyst in an anion exchange membrane water electrolyzer yields a current density of 1 A cm−2 at 1.75 V for 95 h without decay in performance. When the electrocatalyst is integrated into a CO2‐to‐ethylene electrolyzer, a record‐setting full cell voltage of 3 V at current density 1 A cm−2 is achieved.

show abstract

Structure and transformation of oxy-hydroxide films on Ni anodes below and above the oxygen evolution potential in alkaline electrolytes

Cited by 48 publications

References 31 publications

Electrocatalytic oxygen evolution on nickel oxy-hydroxide anodes: Improvement through rejuvenation

Electrocatalytic oxygen evolution on nickel oxy-hydroxide anodes: Improvement through rejuvenation

Transition‐Metal (Co, Ni, and Fe)‐Based Electrocatalysts for the Water Oxidation Reaction

In Situ Formation of Nano Ni–Co Oxyhydroxide Enables Water Oxidation Electrocatalysts Durable at High Current Densities

Contact Info

Product

Resources

About