Electrically tuned photoelectrochemical properties of ferroelectric nanostructure NaNbO_3 films

摘要

Photoelectrochemical (PEC) properties of NaNbO_3 nanostructure ferroelectric films are investigated, and it is demonstrated that the efficiency of PEC water splitting can be tuned (7%-23%) by electrical polarization of the NaNbO_3 films. The NaNbO_3 photoelectrode is fabricated using hydrothermally synthesized NaNbO_3 nanoparticles. Compared to the as-prepared photoanode, photocurrent is enhanced from 0.31 to 0.51 mA/cm~2 (at 1 V vs. Ag/AgCl) for the negatively polarized NaNbO_3 film, whereas the photocurrent is found to decrease from 0.31 to 0.09 mA/cm~2 for the positively polarized NaNbO_3 film. The change in the photoelectrochemical activity after the polarization of NaNbo_3 films has been attributed to the change in the conduction/valence band bending at the semiconductor/ electrolyte interface, leading to a change in the efficiency of charge transfer at the interface. Mott-Schottky studies confirmed the change in band bending after polarization, and electrochemical impedance spectroscopy studies confirmed the modulation in the charge transfer process after polarization.