TY - JOUR

T1 - Enhancement of Interfacial Hydrogen Interactions with Nanoporous Gold-Containing Metallic Glass

AU - Sarac, Baran

AU - Ivanov, Yurii P.

AU - Micusik, Matej

AU - Karazehir, Tolga

AU - Putz, Barbara

AU - Dancette, Sylvain

AU - Omastova, Maria

AU - Greer, A. Lindsay

AU - Sarac, A. Sezai

AU - Eckert, Jürgen

N1 - Publisher Copyright: © 2021 American Chemical Society

PY - 2021/9/15

Y1 - 2021/9/15

N2 - Contrary to the electrochemical energy storage in Pd nanofilms challenged by diffusion limitations, extensive metal–hydrogen interactions in Pd-based metallic glasses result from their grain-free structure and presence of free volume. This contribution investigates the kinetics of hydrogen–metal interactions in gold-containing Pd-based metallic glass (MG) and crystalline Pd nanofilms for two different pore architectures and nonporous substrates. Fully amorphous MGs obtained by physical vapor deposition (PVD) co-sputtering are electrochemically hydrogenated by chronoamperometry. High-resolution (scanning) transmission electron microscopy and corresponding energy-dispersive X-ray analysis after hydrogenation corroborate the existence of several nanometer-sized crystals homogeneously dispersed throughout the matrix. These nanocrystals are induced by PdHx formation, which was confirmed by depth-resolved X-ray photoelectron spectroscopy, indicating an oxide-free inner layer of the nanofilm. With a larger pore diameter and spacing in the substrate (Pore40), the MG attains a frequency-independent impedance at low frequencies (∼500 Hz) with very high Bode magnitude stability accounting for enhanced ionic diffusion. On the contrary, on a substrate with a smaller pore diameter and spacing (Pore25), the MG shows a larger low-frequency (0.1 Hz) capacitance, linked to enhanced ionic transfer in the near-DC region. Hence, the nanoporosity of amorphous and crystalline metallic materials can be systematically adjusted depending on AC- and DC-type applications.

AB - Contrary to the electrochemical energy storage in Pd nanofilms challenged by diffusion limitations, extensive metal–hydrogen interactions in Pd-based metallic glasses result from their grain-free structure and presence of free volume. This contribution investigates the kinetics of hydrogen–metal interactions in gold-containing Pd-based metallic glass (MG) and crystalline Pd nanofilms for two different pore architectures and nonporous substrates. Fully amorphous MGs obtained by physical vapor deposition (PVD) co-sputtering are electrochemically hydrogenated by chronoamperometry. High-resolution (scanning) transmission electron microscopy and corresponding energy-dispersive X-ray analysis after hydrogenation corroborate the existence of several nanometer-sized crystals homogeneously dispersed throughout the matrix. These nanocrystals are induced by PdHx formation, which was confirmed by depth-resolved X-ray photoelectron spectroscopy, indicating an oxide-free inner layer of the nanofilm. With a larger pore diameter and spacing in the substrate (Pore40), the MG attains a frequency-independent impedance at low frequencies (∼500 Hz) with very high Bode magnitude stability accounting for enhanced ionic diffusion. On the contrary, on a substrate with a smaller pore diameter and spacing (Pore25), the MG shows a larger low-frequency (0.1 Hz) capacitance, linked to enhanced ionic transfer in the near-DC region. Hence, the nanoporosity of amorphous and crystalline metallic materials can be systematically adjusted depending on AC- and DC-type applications.

KW - electrochemical hydrogen

KW - equivalent circuit model

KW - gold

KW - metallic glass

KW - palladium

KW - thin films

KW - transmission electron microscopy

KW - X-ray photoelectron spectroscopy

U2 - 10.1021/acsami.1c08560

DO - 10.1021/acsami.1c08560

M3 - Article

C2 - 34491728

AN - SCOPUS:85115636382

VL - 13.2021

SP - 42613

EP - 42623

JO - ACS Applied Materials and Interfaces

JF - ACS Applied Materials and Interfaces

SN - 1944-8244

IS - 36

ER -