2D Nanostructures of CoFe2O4 and NiFe2O4: Efficient Oxygen Evolution Catalyst

Development of cost-effective, efficient electrocatalyst for oxygen evolution reaction (OER) is a challenging issue as OER has sluggish reaction kinetics due to transfer of multi-electrons. In this study, a new strategy has been developed for the synthesis of 2D nanostructures of CoFe2O4 and NiFe2O4 following a wet-chemical route followed by calcination. Following this method nanoplates of CoFe2O4 and nanosheets of NiFe2O4 have been successfully synthesized. These interconnected 2D structures are very efficient for oxygen evolution reaction and it is observed that CoFe2O4 nanoplates and NiFe2O4 nanosheets are catalytically more active compared to nanocubes and nanobipyramids of CoFe2O4 and NiFe2O4. CoFe2O4 nanoplates require only 1.64 V vs. RHE for generating current density of 10 mA/cm2 whereas nanocubes of CoFe2O4 require 1.68 V vs. RHE. Similarly, NiFe2O4 nanosheets require 1.69 V to generate current density 10 mA/cm2 and NiFe2O4 nanobipyramids require 1.77 V vs. RHE to engender 10 mA/cm2 current density. 2D sheet or Plate-like structure with more exposed surface atoms faces more electrolyte to adsorb and react which results in higher electrocatalytic activity.