Elctrocatalytic oxygen evolution reaction on Mg, Al and Fe doped spinel oxides

Abstract

Metal doped cobalt-base spinel type catalysts were prepared by co-precipitation route are considered suitable candidates for OER, ORR, metal air batteries, fuel cells, detoxification of water etc. For the purpose, metal doped oxides with formula MCo₂O₄, M= Mg, Al and Fe were prepared thermal decomposition of their metal carbonate precipitates and characterized by IR, XRD, CV, EIS and Tafel polarization techniques. The IR spectra of oxides showed absorption bands 650 cm^-1 and 560 cm^-1 for respective stretching and bending modes of vibration of Co-O bond at octahedral sites and formation of nano-size ( 18 nm) single phase cubical crystal with spinel geometry was confirmed by XRD powder patterns. The cyclic voltammetric (CV) curves of oxide electrodes in 1 M KOH solution showed a redox peak at E^o= 434 -516 mV for Co²⁺/Co³⁺ reactions. The electrocatalytic activity of oxide electrodes for oxygen evolution reaction in 1M KOH at 25⁰C was also studied by Tafel polarization technique and polarization curve of each oxides showed two Tafel slopes ( 63 and 115 mV/decade) and order of OER is unity.