Effective Formation of a Mn-ZIF-67 Nanofibrous Network via Electrospinning: An Active Electrocatalyst for OER in Alkaline Medium
Selvasundarasekar Sam Sankar, T. K. Bijoy, Sangeetha Kumaravel, Arun Karmakar, Ragunath Madhu, Krishnendu Bera, Sreenivasan Nagappan, Hariharan N. Dhandapani, Gaber A. M. Mersal, Mohamed M. Ibrahim, Debashish Sarkar, S. M. Yusuf, Seung‐Cheol Lee, Subrata Kundu
Abstract
Finding the active center in a bimetallic zeolite imidazolate framework (ZIF) is highly crucial for the electrocatalytic oxygen evolution reaction (OER). In the present study, we constructed a bimetallic ZIF system with cobalt and manganese metal ions and subjected it to an electrospinning technique for feasible fiber formation. The obtained nanofibers delivered a lower overpotential value of 302 mV at a benchmarking current density of 10 mA cm–2 in an electrocatalytic OER study under alkaline conditions. The obtained Tafel slope and charge-transfer resistance values were 125 mV dec–1 and 4 Ω, respectively. The kinetics of the reaction is mainly attributed from the ratio of metals (Co and Mn) present in the catalyst. Jahn–Teller distortion reveals that the electrocatalytic active center on the Mn-incorporated ZIF-67 nanofibers (Mn-ZIF-67-NFs) was found to be Mn3+ along with the Mn2+ and Co2+ ions on the octahedral and tetrahedral sites, respectively, where Co2+ ions tend to suppress the distortion, which is well supported by density functional theory analysis, molecular orbital study, and magnetic studies.