Multiple phase separation of super-abundant-vacancies in Pd hydrides by all solid-state electrolysis in moderate temperatures around 300 °C

Fukada, Yoshiki; Hioki, Tatsumi; Tagaya, Motohiro

doi:10.1016/j.jallcom.2016.07.176

Cited by 9 publications

(4 citation statements)

References 37 publications

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“…As we show, the extent of adhesion of Pd to the solid electrolyte dramatically affects hydrogen insertion. Limited work on the use of solid electrolytes appears in the literature. , It was of interest to us to explore temperature regimes well above those accessible by aqueous or Nafion electrolytes: first to explore the temperature dependence of hydrogen insertion per se and second because a vacancy-rich PdH x phase with a H/Pd ratio greater than 1 has been reported at high temperatures (700–800 °C) and hydrogen pressures (several GPa) . Results presented below are primarily for a temperature of 400 °C at which there is sufficient proton conductivity to achieve reasonable cell impedance.…”

Section: Methodsmentioning

confidence: 99%

“…Typically, synchrotron radiation has been used to measure the H/Pd ratio via XRD measurements of the lattice parameter 39−42 or EXAFS measurements of interatomic distances. 35,42,43 Still, proper calibration of structure dimensions to H/Pd ratio is needed.…”

Section: ■ Introductionmentioning

confidence: 99%

“…These and other complications of the resistivity method have been described in detail by Zhang et al Among previously used methods, operando measurements of the PdH x structure such as X-ray diffraction (XRD) or extended X-ray absorption fine structure (EXAFS) probably have the least uncertainty. Typically, synchrotron radiation has been used to measure the H/Pd ratio via XRD measurements of the lattice parameter − or EXAFS measurements of interatomic distances. ,, Still, proper calibration of structure dimensions to H/Pd ratio is needed.…”

Section: Introductionmentioning

confidence: 99%

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Producing High Concentrations of Hydrogen in Palladium via Electrochemical Insertion from Aqueous and Solid Electrolytes

et al. 2019

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Metal hydrides are critical materials in numerous technologies including hydrogen storage, gas separation, and electrocatalysis. Here, using Pd-H as a model metal hydride, we perform electrochemical insertion studies of hydrogen via liquid and solid state electrolytes at 1 atm ambient pressure, and achieve H:Pd ratios near unity, the theoretical solubility limit. We show that the compositions achieved result from a dynamic balance between the rate of hydrogen insertion and evolution from the Pd lattice, the combined kinetics of which are sufficiently rapid that operando experiments are necessary to characterize instantaneous PdHx composition. We use simultaneous electrochemical insertion and X-ray diffraction measurements, combined with a new calibration of lattice parameter versus hydrogen concentration, to enable accurate quantification of the composition of electrochemically synthesized PdHx. Furthermore, we show that the achievable hydrogen concentration is severely limited by electrochemomechanical damage to the palladium and/or substrate. The understanding embodied in these results helps to establish new design rules for achieving high hydrogen concentrations in metal hydrides.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Producing High Concentrations of Hydrogen in Palladium via Electrochemical Insertion from Aqueous and Solid Electrolytes

et al. 2019

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“…In-situ (operando) measurements including X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) have been employed to identify the lattice parameters and interatomic distances of Pd/PdHx phases, respectively. [34][35][36][37][38] Landers et al 39 utilized in-situ synchrotron XRD and coulometry measurements to understand intercalation/ deintercalation processes for hydrogen in palladium, enabling determination of the electrode potentials where α-and β-PdHx phases were formed. 39 Gao et al 10 utilized in-situ XAS to demonstrate the coexistence of α-and β-phases at potentials above -0.2 V (vs. the reversible hydrogen electrode, RHE), which promoted electrochemical CO2R into formate via a HCOO* intermediate.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Liquid Phase Transmission Electron Microscopy and Electron Diffraction Provides Mechanistic Insight into Electrochemical CO2 Reduction on Palladium/Palladium Hydride Catalysts

Abdellah

Ismail

Siig

et al. 2023

Preprint

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Electrochemical conversion of CO2 (CO2R) offers a sustainable route for producing fuels and chemicals. Pd-based catalysts are effective for selective conversion of CO2 into formate at low overpotentials and CO/H2 at high overpotentials. Furthermore, Pd catalysts undergo morphology and phase structure transformations under reaction conditions that are not well understood. Herein, in-situ liquid phase transmission electron microscopy (LP-TEM) and select area diffraction (SAD) measurements under CO2R conditions is applied to track the morphology and Pd/PdHx phase interconversion as a function of electrode potential, respectively. Correlating in-situ characterization with electrochemical CO2R activity/selectivity measurements, density functional theory and micro-kinetic analyses, the change in Pd/PdHx catalyst selectivity from formate at low overpotentials towards CO/H2 at higher overpotentials is found to result from electrode potential-dependent thermodynamic changes in the reaction energetics and not morphological or phase structure changes, providing insight that can guide advanced understanding and design of improved performance catalysts.

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How to achieve the Fleischmann-Pons heat effect

Staker

2023

International Journal of Hydrogen Energy

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Multiple phase separation of super-abundant-vacancies in Pd hydrides by all solid-state electrolysis in moderate temperatures around 300 °C

Cited by 9 publications

References 37 publications

Producing High Concentrations of Hydrogen in Palladium via Electrochemical Insertion from Aqueous and Solid Electrolytes

Producing High Concentrations of Hydrogen in Palladium via Electrochemical Insertion from Aqueous and Solid Electrolytes

In-Situ Liquid Phase Transmission Electron Microscopy and Electron Diffraction Provides Mechanistic Insight into Electrochemical CO2 Reduction on Palladium/Palladium Hydride Catalysts

How to achieve the Fleischmann-Pons heat effect

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