Transformation of waste onion peels into core-shell Fe3C@ N-doped carbon as a robust electrocatalyst for oxygen evolution reaction

• Published in: Electrochimica acta 2022-08, Vol.422, p.140545, Article 140545
• Main Authors: Bandal, Harshad A., Pawar, Atul A., Kim, Hern
• Format: Article
• Language: English
• Subjects: Carbon; Cementite; Charge efficiency; Charge transfer; Core-shell catalyst; Core-shell structure; Electrocatalysts; Fe3C; Iron carbides; Onions; Oxygen evolution reaction; Oxygen evolution reactions; Shell stability; Shells; Water electrolysis
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140545

Herein, we provide a facile pathway to transform waste onion skins into a competent and stable electrocatalyst for the OER. The obtained catalyst had a core-shell structure wherein, Fe-Fe3C particles were encased within shells of N-doped carbon (FO800). Due to the synergetic interplay among its components, FO800 displayed excellent OER activity. Notably, FO800 delivered the current density of 10 mA cm−2, and 50 mA cm−2 at a low overpotential of 330 mV, and 380 mV with a Tafel slope of 52 mV dec−1. Moreover, at an overpotential of 350 mV FO800 displayed a turnover frequency of 0.02 s−1 indicating that FO800 possesses high intrinsic activity which is comparable to that of RuO2. Owing to the presence of a protective carbon shell FO800 displayed excellent stability for 24 h. The role of Fe3C, N doping, and C shell, in determining the overall OER activity was also examined. Our experimental observations suggest that the incorporation of Fe3C in the N-doped carbon improves the charge transfer efficiencies at the electrode-electrolyte interface by increasing the Donor density. [Display omitted]