Electrically tuned photoelectrochemical properties of ferroelectric nanostructure NaNbO3 films

Abstract

Photoelectrochemical (PEC) properties of NaNbO3 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 NaNbO3 films. The NaNbO3 photoelectrode is fabricated using hydrothermally synthesized NaNbO3 nanoparticles. Compared to the as-prepared photoanode, photocurrent is enhanced from 0.31 to 0.51 mA/cm2 (at 1 V vs. Ag/AgCl) for the negatively polarized NaNbO3 film, whereas the photocurrent is found to decrease from 0.31 to 0.09 mA/cm2 for the positively polarized NaNbO3 film. The change in the photoelectrochemical activity after the polarization of NaNbO3 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.