Study On The Performance And Mechanism Of Piezoelectric Polarization Enhanced Perovskite Oxide Semiconductor Photocatalytic Preparation Of Hydrogen Peroxide

LaFeO₃ perovskite oxide semiconductors have the characteristics of easy synthesis,low production cost,and pollution-free,and are widely used in fields such as organic photocatalytic degradation and device manufacturing.However,due to its low efficiency in separating photo generated carriers,its unsatisfactory photocatalytic properties have seriously affected its subsequent applications.Therefore,the development of technologies that can regulate the carrier transport characteristics in LaFeO₃ is of great significance.The piezoelectric electric polarization field generated by mechanical vibration in piezoelectric materials is a promising technique for controlling the separation and transfer of photogenerated carriers.However,the key to realize the coupling of piezoelectric electric polarization and semiconductor performance lies in the design of multifunctional catalysts with piezoelectric photoelectron effect.The most feasible strategy among them is to prepare composite catalysts,which combine individual piezoelectric materials with semiconductors.In view of this,this study proposes to induce in situ precipitation of piezoelectric phases through excessive doping to achieve self-assembled piezoelectric/semiconductor phase catalysts,achieving efficient photo generated carrier separation efficiency and catalytic efficiency.Firstly,standard stoichiometric LaFeO₃ was synthesized by a one-step solid-state reaction method.The effects of water flow mode,ultrasonic power,ultrasonic frequency,and other conditions on its piezoelectric photocatalytic activity were studied,and the reaction conditions for piezoelectric photocatalysis were optimized.The quenching and aeration experiments indicate that the reaction mechanism for the preparation of H₂O₂ by piezoelectric photocatalysis is is an oxygen reduction pathway.Explored the mechanism of piezoelectric enhanced photocatalysis,that is,the presence of a piezoelectric field can significantly improve the transport of photo generated carriers within the material.Secondly,by introducing excessive Zn dopants on the basis of the synthesized standard stoichiometric LaFeO₃.In the controlled solid-state reaction process,piezoelectric spinel Zn Fe₂O₄ and La₂O₃ phases precipitate in situ together with semiconductor phase（perovskite LaFeO₃）,forming ultrafine LaFeO₃/Zn Fe₂O₄/La₂O₃ composite materials with close contact between each phase.The dynamic piezoelectric electric field is triggered by ultrasound.The optimized composite material has a piezoelectric coefficient(d₃₃)of up to 826pm V^-1 and a H₂O₂ yield of up to 401μmol g^-1 h^-1（in room temperature and pressure environments and pure water）,which is superior to the performance of most reported lead-free piezoelectric photocatalysts.After multiple cycles of testing,the ultra compact composite material is very sturdy,and there is no attenuation of H₂O₂ production capacity.This study provides a universal strategy for the rational design of high-performance piezoelectric photocatalysts.Due to the formation of ultrafine LaFeO₃/Zn Fe₂O₄/La₂O₃ composite materials,each phase has intergranular contact.Thanks to this,the piezoelectric potential field can easily penetrate semiconductor crystals,effectively promoting space charge separation and migration,while suppressing the rapid recombination of electron holes,thus generating more active charges on the surface to participate in the reaction.The composite material achieved high yields of H₂O₂ and ROS through piezoelectric photocatalysis under normal temperature and pressure environments and pure water conditions.Mechanism studies have shown that the production pathway of H₂O₂ is an effective oxygen reduction reaction through a two electron transfer pathway.