Ferroelectric spontaneous polarization steering charge carriers migration for promoting photocatalysis and molecular oxygen activation

Introducing a polarization electric field in photocatalyst system is regarded as a new concept for photocatalytic activity enhancement. In this work, we first unearth that the spontaneous polarization of ferroelectric BaTiO3 promotes the photocatalytic and molecular oxygen activation performance of the narrow-band-gap semiconductor BiOI. Ferroelectric tetragonal-phase BaTiO3 (T-BaTiO3) were prepared via calcination of nonferroelectric cubic-phase BaTiO3 (C-BaTiO3), and their polarization ability was verified via ultrasonication-assisted piezoelectric catalytic degradation. Then, the C-BaTiO3/BiOI and T-BaTiO3/BiOI heterostructures are fabricated by a soft-chemical method. To disclose the influence of ferroelectric spontaneous polarization on charge movement behavior, the photocatalytic and molecular oxygen activation properties are monitored by degradation of methyl orange (MO) and superoxide radical (O2−) evolution under visible light irradiation (λ > 420 nm), respectively. The results demonstrated that T-BaTiO3/BiOI far outperforms C-BaTiO3/BiOI and pristine BiOI. The ferroelectric spontaneous polarization of T-BaTiO3 can steer the migration of photogenerated charge carriers and induce efficient separation, accounting for the strengthened photodegradation and reactive oxygen species O2− production rate (11.02 × 10−7 mol L−1 h−1). The study may furnish a new reference for developing efficient tactics to advance the photocatalytic and molecular oxygen activation ability for environmental chemistry and biochemistry applications.

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