Multilayer Coaxial\nTiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> Nanorod Arrays with\nEnhanced Photoelectrochemical\nProperties under the Ferroelectric Polarization Effect

The introduction of ferroelectrics\nwith spontaneous polarization\ninto photocatalysts can inhibit the recombination of the photoinduced\ncarriers. Ferroelectric photocatalysis provides a promising avenue\nfor pollutant elimination using solar energy. In this work, multilayer\ncoaxial TiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> nanorod arrays\nwere rationally designed and prepared by introducing the BaTiO<sub>3</sub> nanolayer between TiO<sub>2</sub> nanorods and outermost\nWO<sub>3</sub> films using in situ reaction on TiO<sub>2</sub> nanorods\ncombined with sol–gel and dip coating methods. The TiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> nanorods have an average\nlength of 505 nm and an average diameter of 75 nm. The transient photocurrent\ndensity of TiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> nanorod\narrays is 2.3 times higher than that of TiO<sub>2</sub>/WO<sub>3</sub>. After positive poling at 3 V, the transient photocurrent density\nof TiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> increases to 3.1\ntimes the initial value. In addition, the superior degradation efficiency\nof MB under TiO<sub>2</sub>/BaTiO<sub>3</sub>/WO<sub>3</sub> nanorod\narrays after positive poling reaches 92.3% within 2 h. The improved\nphotoelectrochemical performance is due to the spontaneous polarization\nof BaTiO<sub>3</sub>, which can effectively separate the photogenerated\nelectron–hole pairs and accelerate their transfer, thus achieving\ngood photocatalytic activity. This study provides a promising strategy\nfor designing novel ferroelectric photocatalysts with improved performance.