Fabrication of a novel pyramidal 3D MoS2/2D PbTiO3 nanocomposites and the efficient photocatalytic removal of organic pollutants: Effects of the PbTiO3 internal electric field and S-scheme heterojunction formation

Ferroelectric perovskite, such as PbTiO3, has shown great potential in photocatalysis. A novel MoS2/PbTiO3 composite with an S-scheme heterojunction was synthesized by an in-situ hydrothermal process with PbTiO3 nanoplates as the substrate to enhance its photocatalytic performance further. The composite exhibits excellent photocatalytic performance for organic pollutants removal. It achieves a methylene blue (MB, 10 mg/L) removal of 89.6% under simulated sunlight within 120 min, 50.1% and 69.8% higher than pure PbTiO3 and MoS2, respectively. It is worth stating that the composite also has an excellent photocatalytic removal effect on other organic pollutants, such as tetracycline hydrochloride (TC) and methyl green (MG). In the composite, MoS2 presents a pyramidal structure determined by the ferroelectric nature of perovskite PbTiO3. The composite shows an extended optical response and an enhanced charge separation. The quenching tests reveal that OH and O2− are significant reactive substances. A possible photocatalytic reaction mechanism based on S-scheme heterojunction (MoS2/PbTiO3) is proposed. The built-in polarization electric field of PbTiO3, the higher conductivity and the more active edge sites of pyramidal MoS2, and the S-scheme heterojunction formation result in the improved photocatalytic performance of MoS2/PbTiO3 composites.