Enhanced piezo-photocatalytic activity of ZnS/Fe2O3: Benefit from type I junction and weak water flow-induced piezoelectric polarization

Photocatalysis is considered to be a sustainable and less polluting environmental purification technology, however, the limited photogenerated charge separation efficiency and light absorption hinder its large-scale application. Encouragingly, piezocatalysis is proposed as an emerging and appealing strategy to drive the migration and separation of photoinduced carriers. Nevertheless, the source of piezocatalysis is usually derived from high energy-consuming ultrasonic vibration. Herein, we realize superior piezo-photocatalytic chlortetracycline hydrochloride degradation performance stimulated by low-frequency water flow-driven piezoelectric polarization of I-type ZnS/Fe₂O₃ junction. The integration of Fe₂O₃ is beneficial to extend the light absorption from ultraviolet region to visible range and boost the charge separation efficiency of ZnS/Fe₂O₃. Meanwhile, the piezoelectric polarization triggered by weak water flow further promotes the directional separation of photogenerated carriers. With all these merits, the optimized ZnS/Fe₂O₃ shows a piezo-photocatalytic chlortetracycline hydrochloride (CTC) degradation rate of 73.2 % within 20 min, which is 2.8 and 2.1 times that of Fe₂O₃ and ZnS, respectively, and 17.4-fold and 1.1-fold that of single stirring and light, respectively. This work provides a feasible guidance for designing efficient piezo-photocatalysts for in-situ purification of wastewater in natural environmental with effective visible light responsiveness and sensitivity to weak mechanical stress.