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O: Fachverband Oberflächenphysik
O 18: Solid-Liquid Interfaces I: Structure and Spectroscopy
O 18.9: Talk
Monday, March 18, 2024, 17:00–17:15, H 1012
Size Effects and Active State Formation in Cobalt Oxide Nanoparticles during Oxygen Evolution Reaction — •Arno Bergmann1, Felix T. Haase1, Travis E. Jones2, Janis Timoshenko1, and Beatriz Roldan Cuenya1 — 1Department of Interface Science, Fritz-Haber-Institut, Berlin, Deutschland — 2Department of Inorganic Chemistry, Fritz-Haber-Institut, Berlin, Deutschland
Water electrolysis for a CO2-neutral H2 production remains challenging due to the large overpotential required for the anodic oxygen evolution reaction (OER). Cobalt oxides exhibit high catalytic activity for OER but the underlying principles of the oxygen-evolving surface is unkown. Thus, we investigated size-selected CoOx(OH)y nanoparticle (NP) catalysts down to 1 nm using operando X-ray absorption spectroscopy (XAS) combined with DFT calculations.[1] The mass-based activity showed an increasing OER current with decreasing NP size which correlates with a larger accessible surface area. XAS revealed reversible changes in charge density at the Co-O ligand system during OER, being more pronounced with decreasing NP size. Size-dependent changes in the Co-O distance during OER were correlated to charge-transfer between Co and O ligand determined by DFT suggesting electrophilic O sites and allow to extract quantitative information on the near-surface atomic and electronic structure of the oxygen evolving CoOx(OH)y NP near-surface. [1] F.T. Haase et al, Nat Energy 7, 765 (2022).
Keywords: Oxygen Evolution Reaction; Operando Investigation; X-ray absorption spectroscopy; Cobalt Oxides