Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Oxide Surfaces 1
O 49.7: Talk
Wednesday, September 7, 2022, 16:30–16:45, S053
Role of surface termination and orientation on the activity of CoFe2O4(001) and (100) surfaces for water oxidation — •shohreh rafiezadeh and rossitza pentcheva — Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg
CoFe2O4 plays an important role as an anode material for electrochemical water splitting, necessitating detailed understanding of the mechanism of oxygen evolution reaction (OER). This inverse spinel contains alternating layers of octahedral Co and Fe in the (001) direction and mixed Co and Fe layers along the (100) orientation. Here, we employ density functional theory calculations with an onsite Hubbard U term (DFT+U) to investigate the OER performance of CoFe2O4(100) and iron-rich (001) surfaces and compare to the cobalt-rich (001) surface [1]. While the overpotentials of Fe reaction sites are above 0.44 V, octahedral Co shows the lowest overpotential: 0.38 V at the Co-rich (001) surface and even 0.20 V at the mixed Co-Fe (100) surface when terminated with an additional tetrahedral Fe-layer. This reduction of overpotential correlates with a Co2+ oxidation state at the surface and a stabilization of the *OOH intermediate due to hydrogen bonding to neighboring sites. Support by the German Science Foundation (DFG), CRC/TRR 247, project B04 and a computational grant at MagnitUDE are gratefully acknowledged.
[1] H. Hajiyani, R. Pentcheva, ACS Catalysis, 8, 11773-11782 (2018).