Selective Ferroelectric BiOI/Bi ₄ Ti ₃ O ₁₂ Heterostructures for Visible Light-Driven Photocatalysis

Ferroelectric-photocatalyst/photocatalyst heterojunctions have very attractive photocatalytic activities. Besides enhanced charge-carrier separation due to their internal electric fields, charge transfer could be even further enhanced by designing the heterojunction interface. In this work, the polarization-adsorption interaction that exists in ferroelectric materials was employed for successful deposition of BiOI on specific surfaces of Bi ₄ Ti ₃ O ₁₂ plates in the dark at room temperature, where the positively polarized region was found. The crystal structure, morphology, and composition of samples were confirmed by X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Higher photocatalytic activity was achieved by the use of heterojunctions, with the reason behind the enhancement of activity confirmed to be the modified band structure, which contributed to the transfer of photoelectrons from Bi ₄ Ti ₃ O ₁₂ to BiOI, the increased visible light absorption, the increased active site area of positively polarized Bi ₄ Ti ₃ O ₁₂ , and the elimination of the screening layer, which contributes impedance in charge transfer.