Oxygen Reduction and Evolution on Ni-modified Co3 O4 (1?1?1) Cathodes for Zn-Air Batteries: A Combined Surface Science and Electrochemical Model Study.

ABSTRACT: The performance of structurally and chemically well-defined Ni-free and Ni-modified single-crystalline Co3 O4 (1?1?1) thin-film electrodes in the oxygen reduction and evolution reactions (ORR and OER) was investigated in a combined surface science and electrochemistry approach. Pure and Ni-modified Co3 O4 (1?1?1) film electrodes were prepared and characterized under ultrahigh-vacuum conditions by scanning tunneling microscopy and X-ray photoelectron spectroscopy. Both Ni decoration (by post-deposition of Ni) and Ni doping (by simultaneous vapor deposition of Ni, Co, and O2 ) induced distinct differences in the base cyclic voltammograms in 0.5?m KOH at potentials higher than 0.7?V compared with Co3 O4 (1?1?1) electrodes. Also, all oxide film electrodes showed a higher overpotential for the ORR but a lower one for the OER than polycrystalline Pt. Ni modification significantly improved the ORR current densities by increasing the electrical conductivity, whereas the OER onset of approximately 1.47?VRHE (RHE: reversible hydrogen electrode) at 0.1?mA?cm-2 was almost unchanged.

SUBMITTER: Buchner F 

PROVIDER: S-EPMC7318127 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature