Electrospun Fe-Incorporated ZIF-67 Nanofibers for Effective Electrocatalytic Water Splitting.

The explorations of earth-abundant, noble metal-free, highly efficient electrocatalysts for water-splitting reactions have been considered as highly significant for imperishable energy production. Though the metal organic framework (MOF)-based materials are highly promising candidates in the area of material chemistry, the combined properties associated with MOFs and the one-dimensional (1D) fibrous matrix, which can lead to better electrocatalytic performance, have been less explored. Herein, we ascertain a fabrication method for ZIF-67 (zeolite imidazolate framework) nanofibers (NFs), Fe-ZIF NFs, and Fe-ZIF-67 NFs via the wet chemical combined electrospinning (ES) approach. The as-synthesized catalysts were utilized for the electrochemical reaction, which showed a high efficiency toward the oxygen evolution reaction (OER). Compared to other catalysts, the Fe-ZIF-67 NF catalyst showed a very less overpotential of 278 mV at a fixed current density of 10 mA cm-2. The obtained Tafel slope and Rct values are 77 mV dec-1 and 1.2 Ω, respectively. The post-X-ray photoelectron spectroscopy (XPS) analysis revealed the transformation of FeOOH during the OER study along with Co3+ states in mixed Fe-ZIF-67 NFs. In an alkaline electrolyzer, Fe-ZIF-67 NFs were utilized as the anode and a Pt wire as the cathode in 1 M KOH solution, which required a cell voltage of 1.68 V at 10 mA cm-2 current density with astonishing stability. Hence, this work should open a new path for the exploration of efficient non-noble metal catalysts for energy-related applications.