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O: Fachverband Oberflächenphysik

O 67: Solid-Liquid Interfaces III: OER, ORR, CO2RR, etc.

O 67.7: Vortrag

Mittwoch, 18. März 2020, 12:15–12:30, WIL C107

Improvement of OER performance by Fe and Ni doping at the Co₃O₄(001) surface — •Yuman Peng, Hamidreza Hajiyani, and Rossitza Pentcheva — Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg

Using density functional theory (DFT)+U method, we study the oxygen evolution reaction (OER) at the Co₃O₄(001) surface. The stability of different surface terminations as a function of oxygen partial pressure, as well as of pH and applied voltage (Pourbaix diagram) were investigated. The termination with octahedral Co and O ions is found to have the lowest overpotential of 0.46 V for an octahedral Co reaction site. Furthermore, we systematically investigated the effect of Fe and Ni doping on the overpotential. Our results indicate that Ni doping at octahedral site in the surface layer reduces the overpotential from 0.46 to 0.36 V and Fe doping at octahedral site at the tetrahedral Co termination reduces the overpotential from 0.63 to 0.37 V, with the octahedral Co site being the active site. The scaling relationship of Δ G_*OOH and Δ G_*OH binding energies is overall reproduced, the Ni-doped system lying close to the top of the volcano of the overpotentials versus (Δ G_*O-Δ G_*OH). Further insight was gained into the oxidation states of surface ions and in particular the Co active site during OER, by analyzing the magnetic and electronic properties. Support by the DFG, CRC TRR247, IMPRS-Surmat and a computational grant at the magnitUDE of the Center of Computer Science and Simulation are gratefully acknowledged.