From 3D ZIF Nanocrystals to Co–Nx/C Nanorod Array Electrocatalysts for ORR, OER, and Zn–Air Batteries

• Published in: Advanced functional materials Vol. 28; no. 5
• Main Authors: Amiinu, Ibrahim Saana, Liu, Xiaobo, Pu, Zonghua, Li, Wenqiang, Li, Qidong, Zhang, Jie, Tang, Haolin, Zhang, Haining, Mu, Shichun
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 31.01.2018
• Subjects: bifunctional electrocatalysts; Chemical synthesis; Cobalt; Composition effects; Density functional theory; DFT computation; Electrocatalysts; Materials science; Metal air batteries; Metal-organic frameworks; Multifunctional materials; Nanocrystals; nanorod array; Nanorods; Oxygen evolution reactions; Stability; Surface area; Synergistic effect; ZIF nanocrystals; Zinc-oxygen batteries; Zn–air batteries
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201704638

Designing a highly active electrocatalyst with optimal stability at low cost is must and non‐negotiable if large‐scale implementations of fuel cells are to be fully realized. Zeolitic‐imidazolate frameworks (ZIFs) offer rich platforms to design multifunctional materials due to their flexibility and ultrahigh surface area. Herein, an advanced Co–Nx/C nanorod array derived from 3D ZIF nanocrystals with superior electrocatalytic activity and stability toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) compared to commercial Pt/C and IrO2, respectively, is synthesized. Remarkably, as a bifunctional catalyst (Ej = 10 (OER) − E1/2 (ORR) ≈ 0.65 V), it further displays high performance of Zn–air batteries with high cycling stability even at a high current density. Such supercatalytic properties are largely attributed to the synergistic effect of the chemical composition, high surface area, and abundant active sites of the nanorods. The activity origin is clarified through post oxygen reduction X‐ray photoelectron spectroscopy analysis and density functional theory studies. Undoubtedly, this approach opens a new avenue to strategically design highly active and performance‐oriented electrocatalytic materials for wider electrochemical energy applications. A highly active bifunctional electrocatalyst is designed via a structural transformation of 3D ZIF nanocrystals into an array of 1D metal/N functionalized carbon nanorod frameworks. The obtained catalyst exhibits superior bifunctional activity and stability toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), leading to high Zn‐air battery performances compared to the state‐of‐the‐art counterparts.