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

Abstract

• Facile synthesis of Fe 3 O 4 -Bi 2 O 3 nanostructures for energy generation applications. • Fe 3 O 4 -Bi 2 O 3 nanostructures showed highest photocurrent density. • The lowest charge transfer resistance is achieved for Fe 3 O 4 -Bi 2 O 3 nanostructures. • Potentiodynamic of Fe 3 O 4 -Bi 2 O 3 nanostructures showed enhanced properties. Nanostructures of Fe 3 O 4 , Bi 2 O 3 , and Fe 3 O 4 -Bi 2 O 3 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 Fe 3 O 4 , Bi 2 O 3 , and Fe 3 O 4 -Bi 2 O 3 nanostructures, respectively. In the X-ray photoelectron spectroscopy analysis, Fe 2+ , Fe 3+ , Bi 3+ , and Bi 5+ chemical states were observed for the Fe 3 O 4 -Bi 2 O 3 nanostructures. The lowest charge transfer resistance of 46.04 Ω and ion-conducting path resistance of 26.11 Ω were observed in electrochemical impedance spectroscopy in 0.1 M KOH for Fe 3 O 4 -Bi 2 O 3 nanostructures compared with other samples. In the potentiodynamic analysis of the Fe 3 O 4 -Bi 2 O 3 nanostructures, the enhanced Tafel slopes, exchange current density, and limiting diffusion current density under illumination associated with the Fe 3 O 4 and Bi 2 O 3 nanostructures. The maximum photocurrent density of 3.61 × 10 -4 Acm −2 was one order of magnitude higher than that of the pure Fe 3 O 4 and Bi 2 O 3 samples. Hence, the prepared Fe 3 O 4 -Bi 2 O 3 nanostructures can be utilized in energy generation applications.