Deposition of Iron Oxyhydroxide over Graphene/ZIF-12 Composite for Electrocatalytic Water Oxidation

Abstract

Developing the efficient electro-catalyst based on earth abundant elements is demanding for water oxidation reaction. In this study, composite materials consist iron oxyhydroxide (FeOOH), graphene and a cobalt based metal-organic framework (MOF-12) have been fabricated as electro-catalyst for the water oxidation reaction. The catalysts were synthesized by solvothermal process and characterized by various analytical techniques, such as powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The fully characterized materials were then subjected to water oxidation reaction. Under the optimal conditions, the synthesized electro-catalyst (FeOOH0.5:ZIF-120.5/graphene) showed the onset potential 1.4 V Vs reversible hydrogen electrode in 0.5 M KOH solution at pH = 12. The electrocatalyst has shown a low over-potential value of 291 mV for the current density 10mA/cm2. The tafel slop was also measured as 78 mV/dec. The designed electrocatalyst demonstrated outstanding electro-catalytic properties for accelerating oxygen evolution reaction under alkaline conditions.