Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 67: Solid-Liquid Interfaces III: OER, ORR, CO2RR, etc.
O 67.2: Talk
Wednesday, March 18, 2020, 11:00–11:15, WIL C107
ORR and OER on Ni-modified Co3O4(111) - a combined surface science and electrochemical model study for Zn-Air batteries — •Florian Buchner1, Markus Eckardt1,2, Timo Böhler1, Jihyun Kim1, Johannes Schnaidt2, and R. Jürgen Behm1,2 — 1Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany — 2Helmholtz-Institute Ulm (HIU) Electrochemical Energy Storage, Helmholtzstr. 11, D-89081 Ulm, Germany
We report results of a combined surface science and electrochemistry study on the oxygen reduction and oxygen evolution reactions (ORR and OER) on structurally well-defined Ni-free and Ni-modified single crystalline Co3O4(111) thin films. These films, which serve as model for the air cathode in Zn-air batteries, were grown on a Ir(100)-(2x1)O surface under ultrahigh vacuum (UHV) conditions. Co3O4(111) and their Ni-modified derivatives were first characterized by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) under UHV conditions. Post-deposition of Ni on a Co3O4(111) reveals a Ni0 state in XPS, while simultaneous vapor deposition of Ni, Co and O2 results in mixed metal oxides such as NixCo1−xO or NixCo3−xO4) (Ni2+ and Ni3+ states). STM images show extended flat island structures both for Co3O4(111) and mixed metal oxides, while post-deposited Ni forms clusters. The thin films revealed an up-shifted ORR onset for Co3O4 compared to pure Ni and Ir. Nickel doping improves the ORR current densities, while hardly influencing the ORR and OER onsets.