Comparative Oxygen Evolution Reaction performance of cobalt oxide electrocatalyst in combination with various metal ions MCo2O4 (M= Mn2+, Cu2+, Co2+, Zn2+, Fe2+, Mg2+)

Abstract

Oxygen evolution reaction (OER) supported by electrocatalyst is very important reaction in electrochemical system e.g. air-battery based energy storage devices, water splitting, and photo electrochemical cells. Therefore developing inexpensive, non-hazardous, noble metal free, transition metal oxide based electrocatalyst is necessary for energy application and environmental sustainability. MCo2(III)O4 based oxides in combination of various metal ions (Mn2+, Cu2+, Co2+, Zn2+, Fe2+, Mg2+) are studied as OER electrocatalyst in both acidic and basic medium. When deposited on a glassy carbon current collector the comparative LSV polarization plots revealed that in acidic medium FeCo2O4 is the best OER performing electrocatalyst, showing onset potential +1.62 V vs RHE with current 1.66 mA/cm2, while in basic medium it is MnCo2O4 that preforms the best, showing an onset potential +1.53 V vs RHE with OER current density 2.06 mA/cm2. When nickel foam was used as the current collector, Co3O4 shows the best OER performance, with an onset potential 1.508 V vs RHE and OER current 159 mA/cm2 in acidic medium. However in the basic medium the substrate nickel foam outperforms all the oxides combinations with different metal ions due to partially oxidized NiO at nickel foam, showing onset OER potential +1.58 V vs RHE and OER current density 13mA/cm2. No correlation was found between the rates of OER and the bond dissociation energies of the respective metal-oxygen bonds nor the metal-hydroxide bond strength.