Loading PVDF polymer on BiFeO3 films as photoelectrodes for efficient piezoelectric-photoelectrochemical water splitting

Controlling carrier separation by regulating polarization intensity is of great significance for built-in electric field assisted photoelectrochemical (PEC) water splitting. Here, we synthesize BiFeO3/PVDF composite photoelectrodes by loading a certain amount of PVDF on BiFeO3 films. The strong piezoelectric effect of PVDF can improve their piezoelectric built-in electric field to drive carrier separation, and the composite photoelectrode after alkali etching also has an improvement in hydrophily, thus together improving the piezoelectric PEC water splitting. The maximum photocurrent density of BiFeO3/PVDF composite photoelectrodes can be up to 2.03 mA/cm2 at 1.23 V vs RHE, which is significantly enhanced over the photocurrent of bare BiFeO3. In addition, the photocurrent density of BiFeO3/PVDF photoelectrode after alkali etching reaches 2.51 mA/cm2 at 1.23 V vs RHE. The influence of polarization intensity and hydrophilicity on PEC water splitting performance is studied systematically through BiFeO3/PVDF composite systems. This work provides a strategy for designing high activity photoanodes for PEC water splitting in organic/inorganic composites.