FeMnO3/CNT as a synergistic bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions in alkaline medium

• Published in: Materials chemistry and physics 2024-09, Vol.324, p.129695, Article 129695
• Main Authors: Thomas, Annet Anna, Eledath, Anook Nazer, Niranjana, J.S., Muthukrishnan, Azhagumuthu, Bushiri, M Junaid
• Format: Article
• Language: English
• Subjects: Bifunctional electrocatalyst; FeMnO3/CNT; HPRR; OER; ORR
• ISSN: 0254-0584
• DOI: 10.1016/j.matchemphys.2024.129695

The development of highly effective and low-cost electrocatalysts for energy conversion and storage devices is triggered by the sluggish kinetics of oxygen reduction and evolution reactions. Perovskite-based oxides are identified as potential ORR and OER electrocatalysts in an alkaline medium. Thus, the present study discusses the synthesis and characterization of FeMnO3/CNT as a bifunctional catalyst with a low potential gap of 0.89 V. The FeMnO3/CNT composite was synthesized by the solution combustion method and characterized using spectroscopic and electron microscopic techniques. The increase in the ID/IG ratio obtained from the Raman spectra of the FeMnO3/CNT composite with respect to bare CNT indicates the functionalization of CNT. The ORR and OER characteristics of the FeMnO3/CNT composite were analyzed with rotating ring disc electrode and rotating disc electrode measurements. The LSV curve of the FeMnO3/CNT composite synthesized with 0.3g of CNT show better ORR and OER activity. The ORR activity measurements of the composite done in 0.1 M KOH electrolyte show a good onset potential of 0.95 V vs. RHE and a half-wave potential of 0.74 V. The HPRR studies show that the ORR reaction mechanism follows a 2e− + 2e− reduction pathway. The OER measurements in an alkaline medium show an onset potential of 1.63 V vs. RHE with a Tafel slope of 115.3 mV dec−1. Also, this work gives an insight into the fundamental understanding of the synergy between the perovskite and CNT, leading to an enhanced ORR and OER catalytic activity. In addition, the material exhibits good stability for ORR and OER stability studies. [Display omitted] •Solution combustion synthesis is used for anchoring FeMnO3 on carbon nanotubes.•FeMnO3/CNT shows an ORR onset of 0.95 V vs. RHE with a maximum current density of 4.63 mAcm−2.•The HPRR studies show that ORR occurs by a 2e− + 2e− electron pathway for FeMnO3/CNT composite.•FeMnO3/CNT shows bifunctional catalytic activity with ΔE of 0.89 V.