Ferroelectric polarization promoted bulk charge separation for highly efficient CO2 photoreduction of SrBi4Ti4O15.

Abstract Fast recombination of photogenerated charge carriers in bulk remains the major obstacle for photocatalysis nowadays. Developing ferroelectrics directly as photoactive semiconducting catalysts may be promising in view of the strong ferroelectric polarization that induces the anisotropic charge separation. Here, we report a ferroelectric layered perovskite SrBi 4 Ti 4 O 15 as a robust photocatalyst for efficient CO 2 reduction. In the absence of co-catalysts and sacrificial agents, the annealed SrBi 4 Ti 4 O 15 nanosheets with the strongest ferroelectricity cast a prominent photocatalytic CO 2 reduction activity for CH 4 evolution with a rate of 19.8 μmol h⁻¹ g⁻¹ in the gas-solid reaction system, achieving an apparent quantum yield (AQY) of 1.33% at 365 nm, outperforming most of the reported photocatalysts. The ferroelectric hysteresis loop, piezoresponse force microscopy (PFM) and ns-level time-resolved fluorescence spectra uncover that the outstanding CO 2 photoreduction activity of SrBi 4 Ti 4 O 15 mainly stems from the strong ferroelectric spontaneous polarization along [100] direction, which allows efficient bulk charge separation along opposite direction. DFT calculations also disclose that both electrons and holes show the smallest effective masses along a axis, verifying the high mobility of charge carriers facilitated by ferroelectric polarization. This study suggests that the traditionally semiconducting ferroelectric materials that have long been studied as ferro/piezoelectric ceramics now may be powerfully applied in the photocatalytic field to deal with the growing energy crisis. Graphical abstract A ferroelectric layered perovskite semiconductor SrBi 4 Ti 4 O 15 was developed as an efficient photocatalyst for CO 2 reduction. The outstanding photocatalytic activity of SrBi 4 Ti 4 O 15 is stemmed from the strong ferroelectric spontaneous polarization and excellent electronic structure, favoring efficient bulk charge separation. fx1 Highlights • Nanostructured SrBi 4 Ti 4 O 15 ferroelectric with large ferroelectricity was synthesized. • It shows outstanding photocatalytic CO 2 reduction performance in gas phase. • The CH 4 generation rate reaches 19.8 umol h⁻¹ g⁻¹ with a AQE of 1.33% at 365 nm. • Relationship between ferroelectricity and photocatalysis activity was clarified. [ABSTRACT FROM AUTHOR]