Enhanced photocatalytic activity of ferroelectric-based Ag2O/Bi4Ti3O12 hybrids by piezoelectric effect

Combining the ferroelectric/piezoelectric catalysts with photocatalysts was demonstrated as an effective way to facilitate the separation of photoinduced electrons and holes to superior synergistically catalytic activities. In this work, Bi4Ti3O12 (BiTO) nanoflowers were synthesized with Ag2O nanoparticles uniformly decorated on the surfaces, forming xAg2O/BiTO (x = 0–30%) hybrids. The light absorption, photocatalytic activity, and cyclic stability of BiTO nanoflowers were tremendously enhanced after Ag2O decoration. Density functional theory (DFT) calculations have confirmed the large ferroelectric spontaneous polarization along [100] axis in BiTO, which acts as built-in electric field to boost electrons and holes transfer into opposite direction. However, the static built-in electric field can easily be screened by free carriers. To resolve this item, ultrasonic excitation was introduced. The periodic mechanical vibration added on ferroelectrics could maintain the built-in field effective continuously, further improving the photocatalytic activity. Moreover, the ultrasonic frequency and electric poling were found to have influence on the photocatalytic activity. The poled 20%Ag2O/BiTO shows the optimum photocatalytic performance, and the underlying mechanisms were discussed in detail.