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arXiv · 2410.15452

Facile synthesis of palladium hydride via ionic gate-driven protonation using a deep eutectic solvent

Gaia Gavello·Giorgio Tofani·Domenico De Fazio·Stefania Lettieri·Andrea Mezzetta·Lorenzo Guazzelli·Christian S. Pomelli·Renato S. Gonnelli·Erik Piatti·Dario Daghero
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Abstract

Developing novel protocols for hydrogen (H) loading is crucial for furthering the investigation of hydrides as potential high-temperature superconductors at lower pressures compared to recent discoveries. Ionic gating-induced protonation (IGP) has emerged as a promising technique for H loading due to its inherent simplicity, but it can be limited in the maximum density of injected H when ionic liquids are used as a gating medium. Additionally, most ionic liquids are limited by high production costs, complex synthesis, and potential toxicity. Here, we demonstrate that large H concentrations can be successfully injected in both palladium (Pd) bulk foils and thin films (up to a stoichiometry PdH$_{0.89}$) by using a deep eutectic solvent (DES) choline chloride-glycerol 1:3 as gate electrolyte and applying gate voltages in excess of the cathodic stability limit. The attained H concentrations are large enough to induce superconductivity in Pd, albeit with an incomplete resistive transition which suggests a strongly inhomogeneous H incorporation in the Pd matrix. This DES-based IGP protocol can be used as a guideline for maximizing H loading in different materials, although specific details of the applied voltage profile might require adjustments based on the material under investigation.

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Gaia Gavello, Giorgio Tofani, Domenico De Fazio, Stefania Lettieri, Andrea Mezzetta, Lorenzo Guazzelli, Christian S. Pomelli, Renato S. Gonnelli, Erik Piatti, Dario Daghero. 2024-12-17. Facile synthesis of palladium hydride via ionic gate-driven protonation using a deep eutectic solvent. https://doi.org/10.1016/j.molliq.2024.126826

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