Oxygen vacancy engineering of mesoporous Bi-Fe2O3@NC multi-channel microspheres for remarkable oxygen reduction and aqueous/flexible Zn-air batteries

• Published in: Journal of colloid and interface science 2023-11, Vol.650, p.719-727
• Main Authors: Wang, Lixia, Qin, Yanjing, Li, Huatong, Huang, Zhiyang, Gao, Mingcheng, Isimjan, Tayirjan Taylor, Yang, Xiulin
• Format: Article
• Language: English
• Subjects: Aqueous/flexible zinc-air batteries; Bi-Fe2O3@NC; Mesoporous structure; Oxygen vacancies
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2023.07.033

A novel multi-channel mesoporous Bi-Fe2O3 microsphere (Bi-Fe2O3@NC) with abundant oxygen vacancies was successfully constructed by hydrothermal and high-temperature pyrolysis strategy. Bi-Fe2O3@NC exhibits higher half-wave potential and limiting current density than commercial Pt/C for oxygen reduction reaction (ORR). The unique multichannel mesoporous architecture of Bi-Fe2O3@NC combined with abundant oxygen vacancies increases the exposure of active sites, tunes the electronic structure and facilitates efficient electron/mass transport. [Display omitted] •A unique multichannel Bi-Fe2O3@NC mesoporous catalyst was synthesized for ORR.•Bi-Fe2O3@NC exhibits a higher half-wave potential and large limiting current density.•Bi-Fe2O3@NC based aqueous/flexible Zn-air batteries deliver high peak power densities.•Abundant oxygen vacancies regulate the electronic structure and provide new active sites on the catalyst surface. Designing multi-channel mesoporous structure and introducing oxygen vacancies to synergistically enhance oxygen reduction reaction (ORR) activity is crucial for the practical application of zinc-air batteries (ZABs) in the field of energy storage and conversion. Herein, a novel multi-channel mesoporous Bi-Fe2O3 microsphere with abundant oxygen vacancies supported on nitrogen-doped carbon (denoted as Bi-Fe2O3@NC) is constructed and the designated catalyst demonstrates a higher half-wave potential (0.88 V), large limiting current density (5.8 mA cm−2@0.4 V), and superior stability. Besides, the aqueous ZAB utilizing Bi-Fe2O3@NC cathode achieves a high power density of 198.6 mW cm−2 and maintains exceptional stability for 459 h at 5 mA cm−2, superior to most previously reported catalysts. Furthermore, a solid-state ZAB assembled with Bi-Fe2O3@NC shows a power density of 55.9 mW cm−2, highlighting its potential for flexible ZAB applications. The prominent ORR performance of Bi-Fe2O3@NC can be ascribed to its unique multi-channel mesoporous structure and abundant oxygen vacancies, which increase the exposure of active sites and facilitate efficient electron/mass transport. This work provides valuable insights for the rational design of advanced ORR catalysts for the practical requirements of aqueous/flexible ZABs in energy storage and conversion.