Lattice Fluorine and Adsorbed Fluorine Combine with Piezoelectric Polarization to Boost the Separation of Bulk and Surface Carriers of Bi2WO6 for Achieving Efficient Piezo-PEC Performance

The lower polarization intensity and charge separation efficiency are the main factors hindering the wide application of piezoelectric photoelectrocatalytic (piezo-PEC) water splitting. Here, we first introduced lattice fluorine into the bulk Bi 2 WO 6 by fluorination treatment to improve the piezoelectric polarization intensity of Bi 2 WO 6 . In addition, the adsorbed fluorine produced by the fluorination treatment can promote the effective separation of the surface photogenerated charges, thus achieving the effective transfer and separation of the bulk and surface photogenerated charges, further realizing the efficient piezo-PEC water splitting performance. The photocurrent of Bi 2 WO 6 with lattice fluorine and adsorbed fluorine reaches 0.298 mA/cm 2 under ultrasonication by proper fluorination, which is almost 3.3 times that of pure Bi 2 WO 6 under the same conditions. Detailed experimental data shows that the presence of lattice fluorine and adsorbed fluorine can not only effectively improve the bulk piezoelectric polarization of the photoelectric electrode but also effectively optimize the surface photoinduced charge separation. This study provides a promising approach to improve the performance of piezo-PEC by tuning the polarization intensity and surface state of the piezoelectric material.