Fe3O4-Bi2O3 nanostructures for efficient energy generation application-water oxidation under visible light irradiation

Nanostructures of Fe3O4, Bi2O3, and Fe3O4-Bi2O3 were synthesized by a facile coprecipitation process for energy generation applications. Various analyses are carried out to confirm the formation of the nanostructures. The prepared samples showed cube structures with optical bandgaps of 2.21, 2.50, and 2.32 eV for the Fe3O4, Bi2O3, and Fe3O4-Bi2O3 nanostructures, respectively. In the X-ray photoelectron spectroscopy analysis, Fe2+, Fe3+, Bi3+, and Bi5+ chemical states were observed for the Fe3O4-Bi2O3 nanostructures. The lowest charge transfer resistance of 46.04 omega and ion-conducting path resistance of 26.11 omega were observed in electrochemical impedance spectroscopy in 0.1 M KOH for Fe3O4-Bi2O3 nanostructures compared with other samples. In the potentiodynamic analysis of the Fe3O4-Bi2O3 nanostructures, the enhanced Tafel slopes, exchange current density, and limiting diffusion current density under illumination associated with the Fe3O4 and Bi2O3 nanostructures. The maximum photocurrent density of 3.61 x 10-4 Acm-2 was one order of magnitude higher than that of the pure Fe3O4 and Bi2O3 samples. Hence, the prepared Fe3O4-Bi2O3 nanostructures can be utilized in energy generation applications.