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O: Fachverband Oberflächenphysik
O 32: Heterogeneous Catalysis I
O 32.5: Vortrag
Dienstag, 18. März 2025, 11:30–11:45, H25
A comparative DFT+U study of the oxygen evolution reaction at infinite-layer, brownmillerite and perovskite nickelates — •Achim Füngerlings and Rossitza Pentcheva — Department of Physics, University of Duisburg-Essen, Duisburg, Germany
We present a detailed DFT+U investigation of rare earth nickelates RNiOx(001), R = La, Nd; x = 2, 2.5, 3 as anode materials for the oxygen evolution reaction (OER). In these materials the Ni reaction sites at the surface exhibit different coordination, i.e. square-planar in the infinite layer (x = 2, IL), fivefold coordination at the (001) perovskite surface (x = 3) and both fourfold and fivefold coordination at the brownmillerite surface (x = 2.5, BM). Voltammetry measurements find a lower onset potential for the catalytically much more active infinite layer compared to the perovskite counterparts.[1] Moreover, x-ray diffraction measurements suggest that the infinite layer gradually transform into brownmillerite during OER.[1] Our calculations confirm a lower overpotential for both the infinite layer and brownmillerite phases over the respective perovskite phase. The results reveal that the oxidation state of surface Ni has a more profound effect on the catalytic activity than the coordination number, with Ni2+ (found at the IL and the fivefold coordinated BM site) leading to lower (0.53, 0.56 V for R=La; x=2, 2.5) and Ni3+ (at the fourfold coordinated site in BM and the fivefold coordinated site at the perovskite surface) leading to higher overpotentials (0.67, 0.68 V for R=La; x=2.5, 3).
[1] M. Osada, A. Füngerlings, R. Pentcheva, and H. Y. Hwang, to be submitted.
Keywords: Oxygen evolution reaction (OER); Density functional theory (DFT); Infinite-layer; Brownmillerite; Perovskite