Application of weak ferromagnetic BiFeO3 films as the photoelectrode material under visible-light irradiation

Abstract

Bi Fe O 3 films prepared by pulsed laser deposition on Pt∕TiO2∕SiO2∕Si substrates were studied as photoelectrode for water splitting. Under visible-light irradiation, the photocurrent intensity of the polycrystalline BiFeO3 film was found to double that of the amorphous one in a three-electrode cell. The incident photon to current conversion efficiency for the polycrystalline BiFeO3 electrode was approximately 16% at 350nm and 7% at 530nm at 1.5V (versus saturated calomel electrode). The ferromagnetism of the amorphous BiFeO3 film was an order of magnitude weaker than that of the polycrystalline one, supporting the “size effect” explanation for magnetic origin.

Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

“…The I - t test with the varied initial potentials of BFO (Figure 3) implies that a negative initial potential can improve the photo response, while a positive one will weaken the response, which can be explained by the fact that negative OCP appears under photo illumination, and the photo-induced electrons aggregating on the F-doped SnO 2 (FTO) side have to get over the barrier that the positive applied voltage creates to move out to the counter electrode. The dark current density increased to −0.005 mA·cm −2 at an applied potential of −0.4 V, which is much smaller than previous reports [26]. …”

“…According to the I - t measurements (Figure 3, 0 V bias) and P - t (Figure 4a, BFO), we observed a repeatable and stable instantaneous response to the light illumination, coming along with a photocurrent density −0.023 mA·cm −2 and an open circuit potential (OCP) −0.18 V when exposed to light, proving again the high sensitivity of BFO films to light. The −0.023 mA·cm −2 photocurrent density at zero bias voltage was much larger than previous reports [8,26]. The I - t test with the varied initial potentials of BFO (Figure 3) implies that a negative initial potential can improve the photo response, while a positive one will weaken the response, which can be explained by the fact that negative OCP appears under photo illumination, and the photo-induced electrons aggregating on the F-doped SnO 2 (FTO) side have to get over the barrier that the positive applied voltage creates to move out to the counter electrode.…”

Microstructure and ferroic properties of epitaxial [γ-Fe2O3–BiFeO3]−Bi3.25La0.75Ti3O12 composite bilayers

“…[5][6][7] However, its use in real devices is hindered due to various issues not yet fully resolved. Unlike in the bulk phase, where the helicoidal arrangement of the spins results in a zero average macroscopic magnetization, BFO in thin film form also exhibits both magnetic and ferroelectric order parameters at room temperature.…”

REDUCED LEAKAGE CURRENT AND ENHANCED MAGNETIC PROPERTIES OF (Bi,Nd)FeO3 THIN FILMS GROWN ON (Ba,Sr)TiO3 BOTTOM LAYER

“…However, BFO becomes unsuitable for applications owing to its large leakage current due to the oxygen vacancies and Fe 2þ in the samples. 3,4 Using Nd 3þ ions in substitution for larger Bi 3þ ions in the BFO composition, could improve ferromagenetic properties. 5,6 Usually, improvement of leakage and ferroelectric properties of BFO thin films by doping Zr and Ru substitution, codoping La and Ni, codoping La and Nb, codoping Ru and La, or codoping Mn and Ti atoms, but the leakage current density is still higher than 10 À4 A/cm 2 at high electric field of 300 kV/cm.…”