Mechanistic insights into chemical bonded BaTiO3/MoS2 dual piezoelectric heterojunction for Robust Piezo-Photocatalytic performance

To solve the limited active sites, high carrier recombination rate, and the photo-corrosion issues of layered MoS₂, a novel chemically bonded BaTiO₃/MoS₂ (BM-x, x  = 2, 5, 10, and 20) dual piezoelectric heterojunction was synthesized. Density functional theory (DFT) calculations combined with experimental characterizations revealed that chemical bonds are formed between the 3d orbitals of Ti in BaTiO₃ and the 3p orbitals of S in MoS₂. These strong interactions enable BaTiO₃ to be firmly anchored on the surface of 2D MoS₂ sheets and thus enhance the structural stability of the catalyst. Furthermore, the intimate interfacial contact facilitates electron transfer from BaTiO₃ to MoS₂, while the formed type-II heterostructure induces a built-in electric field that significantly improves the generation and separation of photogenerated charge carriers. Under the synergistic effect of ultrasonic vibration and light irradiation, the valence band maximum (VBM) and conduction band minimum (CBM) of the two phases become tilted, resulting in a significant increase in the planar potential difference between them and therefore enhancing the built-in electric field. Thus, the BM-10 sample achieves a high degradation rate and an excellent Cr(VI) removal efficiency. These findings provide new insights into the structural regulation and the optimization of catalytic activity for MoS₂-based piezoelectric photocatalysts.