Role of Electrolyte pH on Water Oxidation for Iridium Oxides

Liang, Caiwu; Katayama, Yu; Tao, Yemin; Morinaga, Asuka; Moss, Benjamin; Celorrio, Verónica; Ryan, Mary; Stephens, Ifan E. L.; Durrant, James R.; Rao, Reshma R.

doi:10.1021/jacs.3c12011

Cited by 14 publications

(5 citation statements)

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“…Consequently, the authors find a much wider deprotonation window of μ 2 -OH and μ 1 -OH, spanning together approximately 1 V, in better agreement to experiments. This behavior is also in accordance with the broad and less structured cyclo voltammogram of IrO 2 (110) and electrochemically prepared IrO x , under acidic pH (See Figure ). Redox transitions of amorphous IrO x with broad potential window were found by the Durrant group using operando UV–vis spectroscopy, matching the sample’s pseudocapacitive behavior in the cyclo voltammogram. ,, They also argue that the broadness of the redox transitions are due to lateral interaction of adsorbates, giving rise to isotherms of Frumkin-type.…”

Section: Ab Initio Atomistic Thermodynamics and The Computational Hyd...supporting

confidence: 86%

“…This behavior is also in accordance with the broad and less structured cyclo voltammogram of IrO 2 (110) and electrochemically prepared IrO x , under acidic pH (See Figure ). Redox transitions of amorphous IrO x with broad potential window were found by the Durrant group using operando UV–vis spectroscopy, matching the sample’s pseudocapacitive behavior in the cyclo voltammogram. ,, They also argue that the broadness of the redox transitions are due to lateral interaction of adsorbates, giving rise to isotherms of Frumkin-type. We note by passing that early works by Conway , and later by Saraby-Reintjes emphasized the importance of Temkin/Frumkin isotherms in electrochemical gas evolution processes, as discussed in Section , either due to surface heterogeneity or due to lateral interactions of adsorbates.…”

Section: Ab Initio Atomistic Thermodynamics and The Computational Hyd...supporting

confidence: 86%

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Toward Realistic Models of the Electrocatalytic Oxygen Evolution Reaction

Jones,

Teschner,

Piccinin

2024

Chem. Rev.

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The electrocatalytic oxygen evolution reaction (OER) supplies the protons and electrons needed to transform renewable electricity into chemicals and fuels. However, the OER is kinetically sluggish; it operates at significant rates only when the applied potential far exceeds the reversible voltage. The origin of this overpotential is hidden in a complex mechanism involving multiple electron transfers and chemical bond making/breaking steps. Our desire to improve catalytic performance has then made mechanistic studies of the OER an area of major scientific inquiry, though the complexity of the reaction has made understanding difficult. While historically, mechanistic studies have relied solely on experiment and phenomenological models, over the past twenty years ab initio simulation has been playing an increasingly important role in developing our understanding of the electrocatalytic OER and its reaction mechanisms. In this Review we cover advances in our mechanistic understanding of the OER, organized by increasing complexity in the way through which the OER is modeled. We begin with phenomenological models built using experimental data before reviewing early efforts to incorporate ab initio methods into mechanistic studies. We go on to cover how the assumptions in these early ab initio simulationsno electric field, electrolyte, or explicit kineticshave been relaxed. Through comparison with experimental literature, we explore the veracity of these different assumptions. We summarize by discussing the most critical open challenges in developing models to understand the mechanisms of the OER.

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Section: Ab Initio Atomistic Thermodynamics and The Computational Hyd...supporting

confidence: 86%

Section: Ab Initio Atomistic Thermodynamics and The Computational Hyd...supporting

confidence: 86%

Toward Realistic Models of the Electrocatalytic Oxygen Evolution Reaction

Jones,

Teschner,

Piccinin

2024

Chem. Rev.

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“…We note that for the chloride-derived sample, a kink in the density of oxidized species as a function of potential has been observed at 1.55 V. This nonlinear dependence can be attributed to the interaction between adsorbates formed on the surface at these potentials, which alter their binding energetics and consequently the potential dependence for their formation. Such a behavior has recently been demonstrated for NiOOH, CoOOH, and IrO x − electrodes.…”

Section: Resultsmentioning

confidence: 78%

“…This increase in activity can be correlated to the smaller increase in the accumulation of oxidation charge and Co–O contraction during OER compared to the ideal value calculated based on the surface area-to-volume ratio changes . Recent mechanistic studies using a combination of spectroscopy and density functional theory calculations on iridium, − nickel, , and cobalt-based catalysts have demonstrated the crucial role of cooperative effects between adjacent oxidized centers in enabling the rate-determining O–O bond formation step. Consequently, the energetics of O–O bond formation might also be affected by a change in the accumulation of oxidized species and the strength of the metal–oxygen bond, which can vary depending on the particle size.…”

Section: Introductionmentioning

confidence: 94%

Unraveling the Role of Particle Size and Nanostructuring on the Oxygen Evolution Activity of Fe-Doped NiO

Rao,

Bucci,

Corby

et al. 2024

ACS Catal.

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Nickel-based oxides and oxyhydroxide catalysts exhibit state-of-the-art activity for the sluggish oxygen evolution reaction (OER) under alkaline conditions. A widely employed strategy to increase the gravimetric activity of the catalyst is to increase the active surface area via nanostructuring or decrease the particle size. However, the fundamental understanding about how tuning these parameters influences the density of oxidized species and their reaction kinetics remains unclear. Here, we use solution combustion synthesis, a low-cost and scalable approach, to synthesize a series of Fe 0.1 Ni 0.9 O samples from different precursor salts. Based on the precursor salt, the nanoparticle size can be changed significantly from ∼2.5 to ∼37 nm. The OER activity at pH 13 trends inversely with the particle size. Using operando timeresolved optical spectroscopy, we quantify the density of oxidized species as a function of potential and demonstrate that the OER kinetics exhibits a second-order dependence on the density of these species, suggesting that the OER mechanism relies on O−O coupling between neighboring oxidized species. With the decreasing particle size, the density of species accumulated is found to increase, and their intrinsic reactivity for the OER is found to decrease, attributed to the stronger binding of *O species (i.e., a cathodic shift of species energetics). This signifies that the high apparent OER activity per geometric area of the smaller nanoparticles is driven by their ability to accumulate a larger density of oxidized species. This study not only experimentally disentangles the influence of the density of oxidized species and intrinsic kinetics on the overall rate of the OER but also highlights the importance of tuning these parameters independently to develop more active OER catalysts.

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“…Recent mechanistic studies using a combination of spectroscopy and density functional theory calculations on iridium, 20,21,22,23,24 nickel 25,26 and cobalt-based catalysts 27 have demonstrated the crucial role of cooperative effects between adjacent oxidized centres in enabling the ratedetermining O-O bond formation step. Consequently, the energetics of the O-O bond formation might also be affected by a change in the accumulation of oxidized species and the strength of the metal-oxygen bond, which can vary depending on particle size.…”

Section: Introductionmentioning

confidence: 99%

Unravelling the role of particle size and nanostructuring on the oxygen evolution activity of Fe-doped NiO

Rao,

Bucci,

Corby

et al. 2024

Preprint

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Nickel-based oxides and oxyhydroxide catalysts exhibit state-of-the-art activity for the sluggish oxygen evolution reaction (OER) in alkaline conditions. A widely employed strategy to increase the gravimetric activity of the catalyst is to increase the active surface area via nanostructuring or decreasing the particle size. However, fundamental understanding about how tuning these parameters influences the density of oxidized species and their reaction kinetics remains unclear. Here, we use solution combustion synthesis, a low-cost and scalable approach, to synthesize a series of Fe0.1Ni0.9O samples from different precursor salts. Based on the precursor salt, the nanoparticle size can be changed significantly from ~2.5 nm to ~37 nm. The OER activity in pH 13 trends inversely with the particle size. Using operando, time-resolved optical spectroscopy, we quantify the density of oxidized species as a function of potential and demonstrate that the OER kinetics exhibits a second order dependence on the density of these species, suggesting that the OER mechanism relies on O-O coupling between neighbouring oxidized species. With decreasing particle size, the density of species accumulated is found to increase, with a decrease in their intrinsic reactivity for OER, attributed to a stronger binding of *O species (i.e. a cathodic shift of species energetics). This signifies that the high apparent OER activity per geometric area of the smaller nanoparticles is driven by their ability to accumulate a larger density of oxidized species. This study not only experimentally disentangles the influence of the density of oxidized species and intrinsic kinetics on the overall rate of OER, but also highlights the importance of tuning these parameters independently to develop more active OER catalysts.

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Role of Electrolyte pH on Water Oxidation for Iridium Oxides

Cited by 14 publications

References 67 publications

Toward Realistic Models of the Electrocatalytic Oxygen Evolution Reaction

Toward Realistic Models of the Electrocatalytic Oxygen Evolution Reaction

Unraveling the Role of Particle Size and Nanostructuring on the Oxygen Evolution Activity of Fe-Doped NiO

Unravelling the role of particle size and nanostructuring on the oxygen evolution activity of Fe-doped NiO

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