Enhancement of the photoelectrochemical water splitting by perovskite BiFeO_3 via interfacial engineering

摘要

Ferroelectric semiconductors like BiFeO3 are increasingly being investigated for applications in solar energy conversion and storage due to their intrinsic ability to induce ferroelectric polarization-driven separation of the photogenerated charge carriers resulting in above-bandgap photovoltages. Nevertheless, the BiFeO3 has been commonly prepared using complex and expensive fabrication techniques, e.g., epitaxial growth, radio frequency sputtering and pulsed laser deposition, which are not economically viable for large-scale production. Herein, we report a facile and scalable method for the fabrication of porous perovskite BiFeO3 photoanodes, as well as sequential interfacial engineering methods to enhance their photoelectrochemical performance for water splitting. Upon atomic layer deposition of a TiO2 overlayer and photo-assisted electrodeposition of a cobalt oxide/oxyhydroxide co-catalyst, the photocurrent density of the engineered photoanode for oxygen evolution reaction (1 M NaOH) significantly increased from negligible photocurrent of the pristine BiFeO3 to 0.16 mA cm(-2) at 1.23 V vs. reversible hydrogen electrode (RHE) under simulated 1 sun irradiation (100 mW cm(-2), AM1.5G spectrum). Furthermore, such functionalization of the BiFeO3 photoanodes shifts the photoelectrochemical oxidation onset potential by 0.7 V down to 0.6 V vs. RHE. The significantly enhanced photoelectro-oxidation activity is facilitated by the improved charge transfer and electrochemical kinetics.