Constructing the Pourbaix diagram of Fe-Cl−-H2O ternary system under supercritical water conditions

Zhou, Xu; Chuan-hua, Liao; Wang, Yinfeng; Zhu, Yuezhao

doi:10.1016/j.electacta.2021.138075

Cited by 13 publications

(4 citation statements)

References 40 publications

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“…Local metal ion concentration may also impact metal dissolution and therefore S-number. Pourbaix diagrams have x and y axes that account for pH and potential, respectively; however, they can also be considered to have a third z axis accounting for metal ion concentration, which adjusts the thermodynamics to be less favorable for dissolution when the metal ion concentration is elevated. , Additionally, the local and bulk metal ion concentration can have stabilizing effects by enabling redeposition of species onto the surface of a catalyst, thereby having a passivating or even self-healing effect. Although not applicable to all materials, some iridates have been observed to develop a more active and stable Ir-rich surface layer when they are electrochemically cycled in an Ir-enriched electrolyte solution …”

Section: Variables Impacting S-number Resultsmentioning

confidence: 99%

“…Pourbaix diagrams have x and y axes that account for pH and potential, respectively; however, they can also be considered to have a third z axis accounting for metal ion concentration, which adjusts the thermodynamics to be less favorable for dissolution when the metal ion concentration is elevated. 101,102 Additionally, the local and bulk metal ion concentration can have stabilizing effects by enabling redeposition of species onto the surface of a catalyst, thereby having a passivating or even self-healing effect.…”

Section: Local and Bulk Environmentmentioning

confidence: 99%

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Advancing the Rigor and Reproducibility of Electrocatalyst Stability Benchmarking and Intrinsic Material Degradation Analysis for Water Oxidation

Seitz

2023

ACS Catal.

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The stability of electrocatalysts is a concern for nearly all materials; degradation can occur via dissolution, leaching, sintering, amorphization, or reduction/oxidation processes. Extreme pH or large applied potentials often exacerbate these effects, but scant fundamental understanding of these processes exists due to complex structural and nanoscale effects in electrocatalysis. Instead, "catalyst stability" is often reported using broad electrode performance metrics, such as measured activity over time. To advance the fundamental understanding and comparison of catalyst materials, we propose that it is necessary to establish improved benchmarking metrics that reflect intrinsic material dynamics and stabilities of catalysts, supports, and substrates as a function of testing parameters, to complement existing metrics that primarily capture the performance of the complete electrode. We consider many degradation processes of lab-scale aqueous media systems, as well as membrane electrode assemblies and proton exchange membrane water electrolyzers, and consider the relatability between the two systems. Herein, we summarize various approaches to standardizing or benchmarking electrocatalyst performance, consider their strengths and weaknesses, and provide an outlook for advancing the rigor, specificity, and reproducibility of these techniques.

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Section: Variables Impacting S-number Resultsmentioning

confidence: 99%

Section: Local and Bulk Environmentmentioning

confidence: 99%

Advancing the Rigor and Reproducibility of Electrocatalyst Stability Benchmarking and Intrinsic Material Degradation Analysis for Water Oxidation

Seitz

2023

ACS Catal.

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“…where E° is the standard potential, T is absolute temperature, R is the gas constant, n is the number of the electrons transferred, F is Faraday's constant, and aA, aB, aH+, aC, and aD are the activity of the species involved in the reaction (assuming activity coefficient of unity, we can use concentration of ionic species instead of their activity). The standard potential (E °) can be calculated as [36,37]:…”

Section: Calculation Of E-ph Diagramsmentioning

confidence: 99%

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Khollari¹,

Zebardast

Asselin

2023

Preprint

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Nuclear power plant steam generator (SG) tubes contain nickel as the main alloying element and there is concern about their corrosion. We optimized models for calculating the high-temperature and high-pressure thermodynamic properties of common nuclear alloy elements and then, calculated the E-pH diagrams for nickel in different concentrations of ammonia or acetate ion between 100 to 260 ℃ at 4.7 MPa. This information is used to predict the corrosion behaviour for nickel in the secondary circuit conditions of CANDU SGs. Based on the results, nickel ammonia and nickel acetate complexes are not stable at low concentrations of ammonia or acetate ion. However, increasing the ammonia or acetate ion concentration resulted in the predominance of Ni(NH3)n2+ or Ni(Ac)n(2−n) at the expense of Ni2+ and NiO, indicating a higher risk of nickel corrosion. Calculations showed that under normal operating conditions with [NH3]tot=5×10−5 and [CH3COO−]tot=10−8 m at 260 ℃ and 4.7 MPa, nickel will be passivated as NiO, preventing the rapid degradation of nickel-based alloys. However, in the presence of a crevice that allows the acetate ion to concentrate, nickel would dissolve in the form of the Ni2+ ion, endangering safe operation of CANDU SGs.

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“…[18][19][20][21][22] Given the extensive use of stainless steels in the nuclear industry, many works have focused on constructing these diagrams in supercritical water environments. 23,24 Since there are no representative Pourbaix diagrams of stainless steels, some authors have used diagrams of pure or binary metals to explain their results, such as the role of Mo in the passivation mechanism of AISI 304 and 316 SS. 25 Despite all these efforts, no representative diagrams are currently available.…”

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confidence: 99%

Deriving Metastable Pourbaix Diagrams of Stainless Steels Using Density Functional Theory Calculations

Malki,

Guillotte,

Baroux

2023

J. Electrochem. Soc.

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This paper presents a novel method for deriving metastable Pourbaix diagrams of Fe-Cr alloys using density functional theory calculations, with the objective of providing a more comprehensive understanding of the thermodynamic equilibria within passive films, considering the metallurgical characteristics of the alloys and the electrochemical polarization conditions. By using advanced numerical tools and optimization algorithms provided by the Materials Project Database, we have developed an approach that incorporates nonequilibrium effects as a corrective factor for the chemical equilibria observed in passive films. Our findings highlight the significant role of nucleation conditions, particularly for the Cr2O3 oxide, in stabilizing the inner layers of the passive films. Lastly, the method was used to investigate the impact of pulsed polarization conditions on AISI 304 stainless steel and proposed a reaction scheme elucidating the enhanced corrosion protective properties of the passive film.

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Constructing the Pourbaix diagram of Fe-Cl−-H2O ternary system under supercritical water conditions

Cited by 13 publications

References 40 publications

Advancing the Rigor and Reproducibility of Electrocatalyst Stability Benchmarking and Intrinsic Material Degradation Analysis for Water Oxidation

Advancing the Rigor and Reproducibility of Electrocatalyst Stability Benchmarking and Intrinsic Material Degradation Analysis for Water Oxidation

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Deriving Metastable Pourbaix Diagrams of Stainless Steels Using Density Functional Theory Calculations

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