Piezocatalytic Performance Of Organic Pollutants Degradation And Hydrogen Production For Sr_0.5Ba_0.5Nb₂O₆ Nanoparticles

Piezocatalysis is a promising way to directly convert weak mechanical energy into chemical energy.Barium strontium niobate（SBN）is a typical piezoelectric material with tetragonal tungsten bronze structure,and this study on its piezoelectric effect in water treatment is beneficial to make up for the weakness of its knowledge and practical implementation at home and abroad,promote the discovery of a novel piezoelectric catalyst,and provide a new method to deal with water pollution.The research on piezocatalytic hydrogen production of SBN can also facilitate the solution of energy problems and provide an alternative strategy to convert mechanical energy into clean energy.Fabrication of heterojunction and modulation of oxygen vacancies are two practical methods to improve the piezocatalytic activity of piezoelectric materials.Oxygen vacancies can promote the adsorption and activation of O₂ by defects on the surface of sample.The built-in electric field generated in the heterojunction can provide driving force for the reverse migration of electron-hole pairs,thus enhancing the piezoelectric catalytic activity.In this work,SBN nanorods with average particle size of～300 nm were synthesized by molten salt synthesis（MSS）method.Afterwards,a simple one-step hydrogen thermal reduction method was used to fabricate oxygen vacancies and self-generated heterojunction in SBN nanorods.The as-fabricated Sr_0.5Ba_0.5Nb₂O₆/Sr₂Nb₂O₇nanocomposites with controllable oxygen vacancies exhibited excellent piezocatalytic activity under ultrasonic vibration.with an about 7 times enhancement of the rate constant(k=0.0395 min^-1)for rhodamine B degradation and an about 10 times enhancement of the water splitting efficiency for hydrogen generation(109.4μmol g^-1 h^-1)for the sample annealed at 500℃under H₂ atmosphere（SBN-500℃）compared to pristine Sr_0.5Ba_0.5Nb₂O₆ nanorods.In addition,the physical mechanism of oxygen vacancy controlling the piezoelectric catalytic performance was revealed by first principles calculation,which provided a new idea for further optimizing the piezoelectric catalytic performance of barium strontium niobate nanoparticles in the future.The experimental results and theoretical calculation of this work demonstrate the essential role of a well-modulated oxygen vacancy concentration on the piezocatalytic activity.This work provides an enlightening guidance for designing self-generated heterojunction piezocatalysts,and offers a new strategy for facilitating the scientific research and practical application of SBN materials.