Chemically Bonded MoS₂/BaTiO₃ dual-piezoelectric heterostructure: An efficient bifunctional catalyst for pollutant degradation and hydrogen evolution

Piezo-photocatalytic materials are capable of simultaneously harvesting solar energy and mechanical energy, thereby exhibiting broad application potentials in energy harvesting and environmental decontamination. In this work, a dual-piezoelectric heterostructure was constructed by chemically bonding BaTiO₃ nanorods with MoS₂ nanospheres via a facile hydrothermal method. Under light irradiation, the formation of Mo-O covalent bonds at the BaTiO₃/MoS₂ interface provides efficient charge-transfer channels for photogenerated electrons (e⁻) and holes (h⁺), effectively suppressing their recombination. Upon the introduction of ultrasonic vibration, the piezoelectric potential induces interfacial band bending, generating a built-in electric field that drives the spatial separation of charge carriers and significantly prolongs their lifetime. Benefiting from the coupled effect of ultrasonic vibration and light irradiation, the MoS₂/BaTiO₃ composite exhibits outstanding degradation performance toward Rhodamine B (20 mg L⁻¹), achieving a removal efficiency of 95.2% within 1 h. The corresponding rate constant (k value) is 8.5 and 16.9 times higher than those of pristine MoS₂ and BaTiO₃, respectively. Moreover, the piezo-photocatalytic hydrogen evolution rate reaches 2874.49 μmol g⁻¹ h⁻¹, which is 2.4 and 2.0 times higher than that of pure MoS₂ and BaTiO₃, respectively. Based on experimental results and theoretical calculations, it was proposed that the type-II heterojunction structure is favorable for electron transfer. The MoS₂/BaTiO₃ nanocomposite exhibits markedly enhanced piezo-photocatalytic degradation performance and hydrogen evolution activity. This study provides valuable insights into the rational design of unique heterostructures capable of simultaneously driving pollutant degradation and hydrogen generation, showing great potential for applications in environmental decontamination and sustainable energy conversion.