Green synthesis of Fe 3 O 4 nanoparticles using aqueous extracts of Pandanus odoratissimus leaves for efficient bifunctional electro-catalytic activity

Iron oxide (Fe 3 O 4 ) nanoparticles (NPs) were prepared at room temperature by one-step synthesis via green chemistry using aqueous extracts of Pandanus odoratissimus leaves. Fe 3 O 4 NPs show uniform particle size distribution with an average diameter of ~ 5.0 nm. BET surface area and average pore diameter of the nanoparticles were found to be ~ 150 m 2 /g and ~ 3.0 nm, respectively. FTIR, Raman, EDAX and XPS studies were also carried out to confirm the phase purity of the prepared materials. Electrochemical water splitting reactions have been carried out using Fe 3 O 4 NPs as electrocatalysts in 0.1 M KOH electrolyte solution. Polarization studies confirm dual nature of Fe 3 O 4 electro-catalysts in water electrolysis for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Potentiodynamic polarization curves reveal low Tafel values of 295 and 126 mV/dec (± 2) for OER and ORR, respectively. The overpotential for water oxidation reaction was found to be ~ 390 mV (± 5) at the current density of 1 mA/cm 2 in 0.1 M KOH. Chronoamperometry and chronopotentiometry experiments were conducted for stability tests of the electrodes.