Bifunctional Oxygen Electrodes with Highly Step-Enriched Surface of Fe–Nx Containing Carbonaceous Thin Film. Issue 6 (19th March 2020)

• Record Type: Journal Article
• Authors: Maruyama, Jun; Maruyama, Shohei; Fukuhara, Tomoko; Mizuhata, Hirotaka; Takenaka, Shinobu; Yoshida, Akihito; Miyazaki, Kohei
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 6(2020)
• Publication Date: 2020-03-19
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ab7e86
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Carbonaceous air cathodes in zinc-air batteries have attracted attention due to their high electron conductivity and low cost; however, the increment in the catalytic activity for the oxygen reduction and evolution in addition to the durability are demanded. Based on a fundamental study about the substantial effect of a three-dimensional active site at a step on a highly-oriented pyrolytic graphite basal plane on the electrode reactions, we attempted to extend the idea to a graphitic carbon fiber surface as a more applied form for the air electrode. Coating of a carbonaceous thin film derived from iron phthalocyanine on finely-etched graphitic carbon fibers produced a highly step-enriched surface demonstrated by the field-emission scanning electron microscope image and Raman spectra with a developed defect peak. The iron K -edge X-ray absorption fine structure showed a step-oriented iron atom coordinated by two nitrogen atoms and a basal plane oriented iron atom coordinated by 4 nitrogen atoms. The step-enrichment enhanced the oxygen reduction and evolution; in particular, the low overpotential phenomenon observed for the fundamental graphite system was reproduced in the carbon fiber paper, both in a half cell and a full cell of the zinc-air battery, which also showed a favorable cycling performance.