Optimizing post-treatment strategies for enhanced oxygen reduction/evolution activity in Co–N–C electrocatalyst

• Published in: International journal of hydrogen energy Vol. 82; pp. 398 - 406
• Main Authors: Yusibova, Gulnara, Ping, Kefeng, Käärik, Maike, Leis, Jaan, Aruväli, Jaan, Šmits, Krišjānis, Käämbre, Tanel, Kisand, Vambola, Karpichev, Yevgen, Tammeveski, Kaido, Kongi, Nadezda
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 11.09.2024
• Subjects: Bifunctional electrocatalyst; M-N-C catalysts; Metal–organic frameworks (MOF); Non-precious metal catalysts; Oxygen evolution reaction (OER); Oxygen reduction reaction (ORR); Bifunctional electrocatalyst; M-N-C catalysts; Non-precious metal catalysts; Oxygen reduction reaction (ORR); Oxygen evolution reaction (OER); Metal–organic frameworks (MOF)
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.07.388

Uncovering the origin of bifunctional oxygen reduction/evolution reaction (ORR/OER) activity of M-N-C type electrocatalysts is essential for their extensive usage in fuel cells and metal-air batteries. The electrochemical properties of heterogeneous M-N-C catalysts depend on the surface structure, which can be modified via different synthetic methods. Herein, we investigate the effect of structure on the activity of Co–N–C electrocatalyst material derived from an amorphous metal-organic framework TAL-2. Specifically, TAL-2 served as the sole precursor for the synthesis of a range of Co–N–C catalysts via various carbonization and acid-leaching modes. Co–N–C catalysts were prepared by carbonizing TAL-2 at different temperatures (700, 800, 900, and 1000 °C) and subsequent acid-leaching using different acids, namely HCl, H2SO4, and HNO3, either individually or in various combinations. This resulted in the generation of 36 distinct catalyst samples, each exhibiting unique morphological characteristics. By systematically varying these parameters, we aimed to unravel the intricate relationship between post-synthetic treatment and the resulting electrocatalytic properties, shedding light on the rational design of Co–N–C catalysts for enhanced ORR/OER. [Display omitted] •Co–N–C catalysts were derived from TAL-2 MOF by varied post-synthetic treatment.•36 unique catalysts were studied to understand structure-activity relationships.•Optimized catalysts showed superior ORR/OER performance with low ΔE values.