Coupled ferroelectric polarization in novelty Sillén–Aurivillius BaBi4TiNbO11Cl material for photocatalysis

The development of efficient and stable photocatalysts is of great significance for tailoring energy crisis and environmental pollution. In this study, novelty Sillén-Aurivillius BaBi4TiNbO11Cl ferroelectric materials were successful synthesized. Results of characterizations exhibit high crystallinity of BaBi4TiNbO11Cl nanoplates with the less impurity phases were fabricated from NaCl/CsCl molten-salt method due to the sufficient precursor ionic diffusion. This layered crystal structure of BaBi4TiNbO11Cl nanoplates can promote the separation of photon-generated carriers, and thus its photocatalytic activity is 3.73 and 1.58 times higher than that of other samples, respectively. Since the distortions of [TiO6] and [NbO6] octahedron in [BiTiNbO7] perovskite blocks cause the ferroelectric polarization in BaBi4TiNbO11Cl, the piezo-photocatalytic performance is also assessed by mechanical force from ultrasound. Further investigations on the piezo-photocatalytic mechanisms of BaBi4TiNbO11Cl nanoplates, the internal electric fields induced by ferroelectric polarization can promote the efficient separation of free charges effectively, which enhances the catalytic activities of about 4.74 times by the synergistic effect of visible light and ultrasonic excitations. This work focuses on revealing the differences of photocatalytic, piezocatalytic and piezo-photocatalytic mechanisms for BaBi4TiNbO11Cl nanoplates, which provides a reference to develop other efficient piezo-photocatalysts of Sillén-Aurivillius layered oxyhalide materials.