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| Home > Publications database > The Role of the d-Band Structure and Adsorption Sites for the Electrocatalytic Hydrogen Evolution on AuPt Alloys |
| Home > Publications database > The Role of the d-Band Structure and Adsorption Sites for the Electrocatalytic Hydrogen Evolution on AuPt Alloys |
| Conference Presentation (Other) | FZJ-2025-03889 |
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2025
Abstract: The hydrogen evolution reaction in acidic media displays a simple electrocatalytic model system with adsorbed hydrogen as the only reaction intermediate. However, after a century of research on this reaction, the electronic properties of electrocatalysts that affect the kinetics are still a field of controversial debate 1. In the current literature 2, trends of the electrocatalytic activity for the hydrogen evolution reaction are typically explained by d-band properties such as the d-band center or upper edge positions in respect to the Fermi level. Here, we critically evaluate this relation for alloys, considering the hydrogen evolution on gold-platinum metal alloys as a test system. By a combination of electrocatalytic measurements and density functional theory (DFT) calculations we revealed new aspects of electronic structure-electrochemical activity coupling. Our measurements show that at small overpotentials, linear combinations of the pure-metals’ Tafel kinetics normalized to the alloy compositions resemble well the measured alloy activities. Adsorption energies determined with the DFT calculations show neighbor-independent activities for Au and Pt surface-sites. The adsorbed hydrogen influences the electron density mostly locally at the adsorption site. In contrast, the density of states of the d-band describes the delocalized conduction electrons in the alloys, which cannot be meaningfully related to the local electronic environments at the hydrogen adsorption site. Hence, we correlate the hydrogen adsorption energies at element-specific surface sites directly to the overpotential-driven reaction mechanisms. We propose a multidimensional reinterpretation of the volcano plot for alloys, which bridges the activity and common bonding strength descriptors of the electrocatalytic theory.
Keyword(s): Energy (1st) ; Chemistry (2nd)
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