Temperature-Controlled Structural Variations of Meticulous Fibrous Networks of NiFe-Polymeric Zeolite Imidazolate Frameworks for Enhanced Performance in Electrocatalytic Water-Splitting Reactions.

Abstract

Developing non-noble, earth-ample, and stable electrocatalysts are highly anticipated in oxygen-evolution reaction (OER) and hydrogen-evolution reaction (HER) at unique pH conditions. Herein, we have synthesized bimetallic (nickel and iron) zeolite imidazolate framework (ZIF)-based nanofibrous materials via a simple electrospinning (ES) process. The structural stability of the fibrous material is subjected to various calcination conditions. We have elaborated the structural importance of the one-dimensional (1D) fibrous materials in electrocatalytic water-splitting reactions. As a result, NiFe-ZIF-NFs (Nanofibers)-RT (Room Temperature) have delivered a small overpotential of 241 mV at 10 mA cm-2 current density in OER and 290 mV at a fixed current density of 50 mA cm-2 in HER at two different pH conditions with 1 M KOH and 0.5 M H2SO4, respectively. Furthermore, it exposes the actual surface area of 27.270 m2 g-1 and a high electrochemical active surface area (ECSA) of 50 μF in OER and 55 μF in HER, which is responsible for the electrochemical performance with better stability. This exceptional activity of the materials is mainly attributed to the structural dependency of the fibrous network through the polymeric architecture.