Superior photopiezocatalytic performance by enhancing spontaneous polarization through post-synthesis structure distortion in ultrathin Bi2WO6 nanosheet polar photocatalyst

The internal polarizations of polar photocatalysts could be enhanced through unit cell structure modulations to improve their photocatalytic performances. In this work, a simple, robust and low-cost NaOH etching process is developed to treat ultrathin Bi2WO6 nanosheets after their creation, resulting in a higher degree of polyhedron distortion (similar to 141 %) and an enhanced piezoelectricity (similar to 260 % the maximum effective piezoelectric coefficient d(33)). Compared with pristine ultrathin Bi2WO6 nanosheets, these etched samples demonstrate an improved charge carrier separation and transfer behavior due to their enhanced internal polarization with the assistance of richer oxygen vacancies, which largely enhance their piezocatalysis (similar to 4.6 times), photocatalysis (similar to 14.3 times) and especially coupled photopiezocatalysis (similar to 33.9 times) performances as demonstrated in their sulfamethoxazole (SMX) degradation performances. center dot O-2(-), O-1(2) and h(+) are proven to be main reactive oxygen species (ROSs) during their photopiezocatalytic process and they could also work well in the real water matrix.