Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 75: Fundamentals of Catalysis I

O 75.7: Vortrag

Donnerstag, 4. April 2019, 12:15–12:30, H5

Density functional study of hydrogen adsorption on 55-atom Pt-Ni nanoclusters — •Olli Ahlstedt¹ and Jaakko Akola^1,2 — ¹Laboratory of Physics, Tampere University of Technology, Finland — ²Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway

Density functional theory calculations were performed on small 55-atom Pt-Ni nanoclusters to study their activity towards the hydrogen evolution reaction (HER). Two Pt_nNi_55−n compositions, Pt₁₂Ni₄₃ and Pt₂₀Ni₃₅, were studied in the gas phase and on an Al₂O₃ support. The critical hydrogen coverages were determined using the method based on the differential free energy of hydrogen adsorption. The free energy of hydrogen adsorption, Δ G_H^*, was used as a descriptor of the HER activity.

Ni₃ hollow sites were discovered to be the strongly binding sites for hydrogen. The clusters adsorb approximately four H atoms per facet before the hydrogen adsorption becomes endergonic, therefore the critical hydrogen coverages on the clusters are high. The obtained Δ G_H^* descriptor values are smaller than 0.1 eV in the gas phase and on the support, suggesting that the clusters are catalytically active towards HER.