Neutral and alkaline chemical environment dependent synthesis of Mn3O4 for oxygen evolution reaction (OER)

Abstract

Co-precipitation assisted hydrothermal synthesis was employed to prepare Mn3O4 electrocatalysts for efficient electrochemical water oxidation. Tetragonal structure of high crystalline and pure phase Mn3O4 nanostructures was confirmed by X-ray diffraction (XRD) spectra. Physical characteristics such as vibration, optical and morphology of the electro catalysts were examined and confirmed by Raman spectra, Fourier Transform Infrared Spectra (FTIR), photoluminescence spectra (PL) and ultra-violet diffuse reflection spectra (UV-DRS) respectively. Mn3O4 electro catalysts were deposited on GCE electrode for investigating the electrochemical behavior. The electrochemical water splitting application was demonstrated by the prepared Mn3O4 electro catalysts in conventional three electrode cell with Hg/HgO as a reference electrode and Pt mesh as a counter electrode. Higher current density of 1.31 mA/g with lowest Tafel slope value of 63 mV/dec was achieved for the prepared electro catalyst synthesized in base pH condition. Good stability of 55% over 12 h long time was achieved for the electro catalysts in alkaline medium under continuous electrochemical reaction with good retention in performance. Hence, the controlled alkaline environmentally synthesized Mn3O4 electro catalysts prepared in this work achieved the good standard of highly efficient electrode material for electrochemical water splitting applications.