Switchable Charge‐Transfer in the Photoelectrochemical Energy‐Conversion Process of Ferroelectric BiFeO₃ Photoelectrodes

Abstract

Instead of conventional semiconductor photoelectrodes, herein, we focus on BiFeO3 ferroelectric photoelectrodes to break the limits imposed by common semiconductors. As a result of their prominent ferroelectric properties, the photoelectrodes are able to tune the transfer of photo‐excited charges generated either in BiFeO3 or the surface modifiers by manipulating the poling conditions of the ferroelectric domains. At 0 V vs Ag/AgCl, the photocurrent could be switched from 0 μA cm−2 to 10 μA cm−2 and the open‐circuit potential changes from 33 mV to 440 mV, when the poling bias of pretreatment is manipulated from −8 V to +8 V. Additionally, the pronounced photocurrent from charge injection of the excited surface modifiers could be quenched by switching the poling bias from +8 V to −8 V.

Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

“…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.…”

“…For example, polycrystalline BFO photo electrode was applied for water photo-oxidation [6]; an enhanced ferroelectric PV response of multilayered BiFeO 3 /BaTiO 3 was observed [7]. The photoelectrochemical (PEC) response of BFO with ferroelectric materials has also been reported [8,9]. Findings imply the promising potential applications of BFO films in terms of photocatalysts, photovoltaic cells, multifunction sensors, etc.…”

A Photoferroelectric Perovskite‐Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects

“…[3a, 4] This fascinating effect suggests that ferroelectric materials are viable photovoltaic candidates capable of harvesting energy from light. [9] Although ferroelectric PVEs have stimulated intensive research in the last decade,i t remains challenging to design photoferroelectric candidates because of al ack of knowledge regarding the conclusive mechanism and origin of ferroelectric PVEs. [9] Although ferroelectric PVEs have stimulated intensive research in the last decade,i t remains challenging to design photoferroelectric candidates because of al ack of knowledge regarding the conclusive mechanism and origin of ferroelectric PVEs.…”

Relaxor behavior and photocatalytic properties of BaBi2Nb2O9

“…Therefore, it is urgent to explore novel photocatalysts to solve the energy crisis and environmental pollution issues. Ferroelectric oxides with a perovskite structure, such as BaTiO 3 and BiFeO 3 , have emerged as promising candidates for photocatalysts . Their built‐in internal electric fields can enhance the transport of photoinduced charge carriers and thus accelerate their separation .…”