Hydrogen Overvoltage on Rhenium and Niobium Electrodes

Joncich, M. J.; Stewart, Leland; Posey, F.A.

doi:10.1149/1.2423674

Cited by 26 publications

(9 citation statements)

References 19 publications

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“…WO 3 is a good example for this effect [ 31 ]. (3) The experimental data are affected by the charge transport through the film, which is very difficult to correct for [ 32 ]. Therefore, for this class of electrodes it is impossible to relate DFT data for hydrogen adsorption with experimental data.…”

Section: Final Remarksmentioning

confidence: 99%

Volcano plots in hydrogen electrocatalysis – uses and abuses

Quaino¹,

Juárez²,

Santos³

et al. 2014

Beilstein J. Nanotechnol.

494

415

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SummarySabatier’s principle suggests, that for hydrogen evolution a plot of the rate constant versus the hydrogen adsorption energy should result in a volcano, and several such plots have been presented in the literature. A thorough examination of the data shows, that there is no volcano once the oxide-covered metals are left out. We examine the factors that govern the reaction rate in the light of our own theory and conclude, that Sabatier’s principle is only one of several factors that determine the rate. With the exception of nickel and cobalt, the reaction rate does not decrease for highly exothermic hydrogen adsorption as predicted, because the reaction passes through more suitable intermediate states. The case of nickel is given special attention; since it is a 3d metal, its orbitals are compact and the overlap with hydrogen is too low to make it a good catalyst.

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Section: Final Remarksmentioning

confidence: 99%

Volcano plots in hydrogen electrocatalysis – uses and abuses

Quaino¹,

Juárez²,

Santos³

et al. 2014

Beilstein J. Nanotechnol.

494

415

View full text Add to dashboard Cite

show abstract

“…For tungsten [118,171,172], molybdenum [149,173], and niobium [174][175][176], two Tafel regions with slopes of 60-80 mV and 100-120 mV have been reported. For Wand Nb, there were no data concerning the dependence of the overpotential on the solution composition, while a stronger dependence for the upper part of the polarization curve was indicated in the case of Mo[173].…”

Section: 6* Evolution Of Hydrogen At Other Cathodesmentioning

confidence: 99%

Charge Transfer Reactions in Electrochemical and Chemical Processes

Krishtalik

1986

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“…( 6), is found to be the rate determining step (in the case of active metals such as Nb, the passive film is frequently in place during these measurements making them of little value to this discussion). [48] This implies that the fugacity on the surface may be orders of magnitude greater than the ambient pressure, but also orders of magnitude below the calculated theoretical fugacities.…”

Section: B Kinetic Limitationsmentioning

confidence: 93%

“…It is reported that in this environment the values for and i 0 are 0.10 (V) and 1 x10 -4 (mA/cm 2 ) respectively. [4,48] Assuming that the EP current density is 100 mA/cm 2 , then eq. ( 29) becomes = (0.10) log 100 0.0001 0.6…”

Section: E Electropolishingmentioning

confidence: 99%

Thermodynamic Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Accelerator Cavities

Ricker¹

2009

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During the fabrication of niobium superconducting radio frequency (SRF) particle accelerator cavities procedures are used that chemically or mechanically remove the passivating surface film of niobium pentoxide (Nb 2 O 5 ). Removal of this film will expose the underlying niobium metal and allow it to react with the processing environment. If these reactions produce hydrogen at sufficient concentrations and rates, then hydrogen will be absorbed and diffuse into the metal. High hydrogen activities could result in supersaturation and the nucleation of hydride phases. If the metal repassivates at the conclusion of the processing step and the passive film blocks hydrogen egress, then the absorbed hydrogen or hydrides could be retained and alter the performance of the metal during subsequent processing steps or in-service. This report examines the feasibility of this hypothesis by first identifying the postulated events, conditions, and reactions and then determining if each is consistent with accepted scientific principles, literature, and data. Established precedent for similar events in other systems was found in the scientific literature and thermodynamic analysis found that the postulated reactions were not only energetically favorable, but produced large driving forces. The hydrogen activity or fugacity required for the reactions to be at equilibrium was determined to indicate the propensity for hydrogen evolution, absorption, and hydride nucleation. The influence of processing conditions and kinetics on the proximity of hydrogen surface coverage to these theoretical values is discussed. This examination found that the hypothesis of hydrogen absorption during SRF processing is consistent with published scientific literature and thermodynamic principles.

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Hydrogen Overvoltage on Rhenium and Niobium Electrodes

Cited by 26 publications

References 19 publications

Volcano plots in hydrogen electrocatalysis – uses and abuses

Volcano plots in hydrogen electrocatalysis – uses and abuses

Charge Transfer Reactions in Electrochemical and Chemical Processes

Thermodynamic Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Accelerator Cavities

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