Multilayer Coaxial TiO₂/BaTiO₃/WO₃ Nanorod Arrays with Enhanced Photoelectrochemical Properties under the Ferroelectric Polarization Effect

The introduction of ferroelectrics with spontaneous polarization into photocatalysts can inhibit the recombination of the photoinduced carriers. Ferroelectric photocatalysis provides a promising avenue for pollutant elimination using solar energy. In this work, multilayer coaxial TiO2/BaTiO3/WO3 nanorod arrays were rationally designed and prepared by introducing the BaTiO3 nanolayer between TiO2 nanorods and outermost WO3 films using in situ reaction on TiO2 nanorods combined with sol–gel and dip coating methods. The TiO2/BaTiO3/WO3 nanorods have an average length of 505 nm and an average diameter of 75 nm. The transient photocurrent density of TiO2/BaTiO3/WO3 nanorod arrays is 2.3 times higher than that of TiO2/WO3. After positive poling at 3 V, the transient photocurrent density of TiO2/BaTiO3/WO3 increases to 3.1 times the initial value. In addition, the superior degradation efficiency of MB under TiO2/BaTiO3/WO3 nanorod arrays after positive poling reaches 92.3% within 2 h. The improved photoelectrochemical performance is due to the spontaneous polarization of BaTiO3, which can effectively separate the photogenerated electron–hole pairs and accelerate their transfer, thus achieving good photocatalytic activity. This study provides a promising strategy for designing novel ferroelectric photocatalysts with improved performance.