A1 Refereed original research article in a scientific journal
Revealing Catalytic Properties of Palladium/Gold Systems toward Hydrogen Evolution, Oxidation, and Absorption with Scanning Electrochemical Microscopy
Authors: Schott, Christian M.; Holl, Julia; Zazpe, Raul; Kopp, Michael; Man, Ondřej; Thalluri, Sitaramanjaneya, M.; Rodriguez-Pereira, Jhonatan; Schneider, Peter M.; Song, Kun-Ting; Keles, Emre; Peljo, Pekka; Jasielec, Jerzy J.; Gubanova, Elena L.; Macak, Jan M.; Bandarenka, Aliaksandr S.
Publisher: American Chemical Society (ACS)
Publication year: 2025
Journal: ACS Catalysis
Journal name in source: ACS Catalysis
Volume: 15
Issue: 11
First page : 9035
Last page: 9046
ISSN: 2155-5435
eISSN: 2155-5435
DOI: https://doi.org/10.1021/acscatal.5c00783
Web address : https://doi.org/10.1021/acscatal.5c00783
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/498672133
Palladium (Pd) is an active catalyst for various reactions, such as hydrogen evolution (HER) and hydrogen oxidation (HOR) reactions. However, its activity can be further optimized by introducing strain and ligand effects from Pd deposition onto suitable substrates like gold (Au). In this study, we use scanning electrochemical microscopy (SECM) to investigate the catalytic properties of such Pd/Au systems. For the HER, a sub-monolayer of Pd (PdML) was electrochemically deposited onto half of a polycrystalline (pc) Au substrate with underpotential deposition (UPD). The localized activity measurements revealed improved HER kinetics for Pd atoms at the Pd/Au border in 0.1 M HClO4. As a consequence, a set of Pd/Au samples with increasing density of Pd/Au borders was synthesized by atomic layer deposition (ALD). These ALD Pd deposits have an increased thickness compared to a sub-monolayer, which makes hydride formation thermodynamically viable. Because of this, the samples were investigated for the HOR/H absorption activity using the redox competition (RC) mode. We highlight the influence of cations in 0.1 M AMOH (AM = Li+, Na+, K+, Rb+, Cs+) electrolytes on the HOR/H absorption activity, displaying higher activities for larger cations: jLiOH < jNaOH < jKOH < jRbOH < jCsOH. From the spatial and temporal resolution of the activity, active spots are identified, which expand with time and diminishing hydrogen concentration in the electrolyte. Additional laser-induced current transient (LICT) experiments confirm the dependency between cation and electrocatalytic activity observed with RC-SECM.
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Funding information in the publication:
This project has received funding from (1) the European Union’s Horizon 2020 research and innovation program under Grant Agreement HERMES No. 952184, (2) the Ministry of Education, Youth and Sports of the Czech Republic, within the support via CEMNAT (LM2023037) and CzechNanoLab (LM2023051) infrastructures, providing ALD, SEM, EDX, XPS, AFM, and EBSD accesses, (3) DFG project BA 5795/8- 1, and (4) DFG collaborative research center within SFB CRC 1625, project no. 506711657. We thank Dr. Ludek Hromadko and MSc. Veronika Cicmancova for their support with SEM analyses and Dr. Michal Kurka for the AFM characterization.