Evaluating Zn ferrite (Zn x Fe 3-x O 4 ; 0 ≤ x ≤ 1) for alkaline water oxidation: electrochemical and operando spectro- electrochemical study

Abstract

The present research work describes the fabrication of zinc ferrite nanoparticles with varying stoichiometric compositions (ZnxFe3-xO4; x= 0.25, 0.5, 0.75, and 1) and their electrocatalytic performance for the oxygen evolution reaction (OER). Egg white was employed as a precursor material during the thermal decomposition process to produce the catalysts. OER performances of four synthesized catalysts in the alkaline medium (1.0 M KOH) were investigated by physicochemical (XRD, FTIR and SEM) and electrochemical (CV, EIS, Tafel polarization) techniques. Among four Zn ferrite catalysts of different stoichiometry, just Zn0.25Fe2.75O4 exhibited the optimum catalytic activity, with the current density of 1 mA cm-2 at the overpotential of 454 mV, and with Tafel slope of 107 mVdec-1. The Arrhenius plot was applied to determine thermodynamic parameters such as activation energy and electrochemical entropy of reaction, which were found to be 54.22 kJ mol-1 and -74 J K-1 mol-1, respectively.