Perovskite BiFeO₃thin film photocathode performance with visible light activity

Abstract

Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of -0.004 mA cm(-2) at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h(-1) of O2 was produced at an external bias of -0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to -0.07 mA cm(-2) at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h(-1) for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV-vis spectroscopy, Mott-Schottky plots and j-v curve analysis.

Enhanced Photoelectrochemical Performance in Reduced Graphene Oxide/BiFeO3 Heterostructures

“…The RGO3/BFO sample shows a much stronger response as compared with that of BFO, confirming the superiority of the former in photoenergy conversion. For example, the photocurrent density of the RGO3/BFO sample is ≈−160 µA cm −2 at −0.2 V versus Ag/AgCl, which is also higher than that reported for the BFO polycrystalline film with 2% Ag (−70 µA cm −2 at −0.2 V vs Ag/AgCl), and higher than BFO/ε‐Fe 2 O 3 vertical heteroepitaxy films (190 µA cm −2 at 0.6 V vs Ag/AgCl) . Compared with these studies, our RGO/BFO composite photoelectrodes not only show superior PEC performance, but also exhibit the advantage of the low‐cost and simple fabrication process.…”

Computation of Electronic Energy Band Diagrams for Piezotronic Semiconductor and Electrochemical Systems

“…A ferroelectric insulator between the metal and the semiconductor can have a profound effect on the resultant electrical potential profile in the metal/ferroelectric insulator/ piezoelectric semiconductor heterojunction (shown in Figure 4a). [26][27][28][29][30] Figure 4b,c shows the result of using a ferroelectric insulator with −P r and P r , respectively, before the metal and semiconductor exchange charge and equilibrium is established. As seen in the Figure 4d,e, the ferroelectric polarization affects the driving force for charge exchange between the metal and the semiconductor V 1 − V 4 .…”

Interfacial Interactions in Monolayer and Few‐Layer SnS/CH3NH3PbI3 Perovskite van der Waals Heterostructures and Their Effects on Electronic and Optical Properties

“…As a representative hybrid organic–inorganic perovskite, methylammonium lead iodide [CH 3 NH 3 PbI 3 (MAPbI 3 )] has unique optical and electronic properties, such as limited charge recombination, long carrier diffusion length, and broadband light absorption . In particular, experiments have demonstrated that long‐range hot‐carrier transport can persist over tens of picoseconds and about 600 nm in MAPbI 3 , which make it an excellent light absorber in solar cells, with potential applications in photocatalysis . However, water molecules can interact with its crystal lattice through hydrogen bonding, resulting in collapse of the MAPbI 3 crystal structure.…”

“…[16] In particular, experiments have demonstrated that long-range hot-carrier transportc an persist over tens of picoseconds and about 600 nm in MAPbI 3 ,w hich make it an excellent light absorber in solar cells, [17][18][19][20] with potential applicationsi np hotocatalysis. [21][22][23] However, water molecules can interact with its crystal lattice through hydrogen bonding, resulting in collapse of the MAPbI 3 crystal structure. Its instability upon exposure to humid air and in aqueous solutions hinders the application of MAPbI 3 as ap hotocatalyst.…”