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Electrodeposited manganese oxide on superhydrophobic nickel-mesh for application in gas diffusion electrode

Poster presented at Bunsentagung 2019, Jena (30.5.-1.6.2019)
: Bekisch, Artur; Skadell, Karl; Schulz, Matthias; Stelter, Michael

Adelhelm, P. ; Deutsche Bunsen-Gesellschaft für Physikalische Chemie e.V. -DBG-, Frankfurt/M.; Univ. Jena:
Functional materials. Bunsentagung 2019. Book of abstracts : 118th General Assembly of the German Bunsen Society for Physical Chemistry; 30 May-1 June 2019, Jena, Germany
Frankfurt am Main: DBG, 2019
ISBN: 978-3-947197-12-5
ISBN: 3-947197-12-8
Bunsentagung <118, 2019, Jena>
Fraunhofer IKTS ()
manganese oxide; electrodeposition

Technologies like alkaline electrolyzers, alkaline fuel cells and metal-air-batteries are limited by low conversion efficiency. One reason is that applied gas diffusion electrodes have slow oxygen conversion reactions [1]. It is necessary to optimize gas-diffusion electrodes to provide the latent high energy density. The integration of a hierarchic surface architecture similar to the surface of floating fern is a suitable option therefore. The combination of a macroscopic superhydrophobic metal-mesh or –foam with a microscopic hydrophilic bifunctional (OER/ORR) catalyst formed a hierarchic surface architecture. This results in a stable air layer on the gas diffusion electrode surface in an aqueous media. Thus, a stable three-phase boundary will be established, and charge and discharge reactions are accelerated. Because the oxygen transport to the catalytic active regions of the electrode will be improved [2].Furthermore, weaknesses of conventional gas diffusion electrode designs (poor longterm stability of materials) can be overcome and higher performance and efficiency can be achieved [3].It was possible to maintain a superhydrophobic surface on a nickel-mesh after an electrodeposition of manganese oxide. Firstly, the nickel surface was etched inhydrochloric acid, temperature treated at 350 °C and dipped in stearic acid to generate a superhydrophobic surface. Afterwards, the electrodeposition of manganese oxide followed with an electrolyte composed of manganese(II) acetate tetrahydrate and sodium sulfate. The fabricated superhydrophobic electrodes were electrochemically characterized in a symmetric cell and with a rotating disc electrode setup to evaluate the activity of the electrodeposited manganese oxide. Measurements of the surface area (nitrogen sorption), surface structure (SEM) and manganese oxide phase structure (XRD) were also performed.