Charge Coupling Enhanced Photocatalytic Activity of BaTiO₃/MoO₃ Heterostructures

In this work, we proposed an efficient heterostructure photocatalyst by integrating the ferroelectric BaTiO₃ (BTO) layer with the semiconductor MoO₃ layer, availing the ferroelectric polarization of BaTiO₃ and high generation of photoinduced charge carriers in the MoO₃ layer. The effect of MoO₃ layer thickness (t_MoO) on the photocatalytic efficiency of the BTO/MoO₃ heterostructures is found to be optimum at t_MoO = 67 nm as t_MoO varies from 40 to 800 nm. The BTO/MoO₃ heterostructure with t_MoO = 67 nm exhibits a high efficiency of 86% for the degradation of rhodamine B (RhB) under the exposure of UV-visible light for 60 min. The photocatalysis rate kinetics analysis reveals that the rate constant in the heterostructure is 1.7 times of pure BTO and 3.2 times of pure MoO₃ films. The enhanced photocatalytic activity in the heterostructures is attributed to the electric field-driven carrier separation due to the ferroelectric polarization and the heterojunction band bending. The charge coupling effect between BaTiO₃ and MoO₃ is evident from the current-voltage characteristics. The maximum lattice strain in the heterostructure with t_MoO = 67 nm as evident from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis further confirms the charge transfer between the layers. The degradation as well as decolorization efficiency of the BTO/MoO₃ heterostructure is higher than that of pure BTO and MoO₃ films. Radical trapping experiments reveal that electrons are the major contributors to the photocatalytic activity of the BTO/MoO₃ heterostructure. The reusability test shows only a reduction of 5% in the efficiency of the heterostructure after five photocatalysis cycles. The heterostructure can also efficiently decompose the other dyes such as rose bengal and methyl violet. Thus, our findings prove that an efficient and reusable photocatalyst can be designed through the integration of the ferroelectrics with the semiconductor layers.