Study On Preparation Of Layered Perovskites Bi-Based Titanate And Their Photo/Piezocatalytic Properties

The construction of a polarization field can promote the charge separation and increase the catalytic activity,so this field has become one of the research hotspots in recent years.Among them,the perovskite bismuth-based layered titanate owns huge potentials of photocatalysis and piezocatalysis as it possess both ferroelectric,piezoelectric and semiconductor optoelectronic properties.Based on a comprehensive review of the mechanism,material system,modification,characterization and application prospects of piezoelectric catalysis and piezoelectric photocatalysis in the past ten years,this article analyzed the existing problems at this stage and carried out the study of structure,physical and chemical properties of typical perovskite-type layered bismuth materials Bi4Ti3O12,Sr Bi4Ti4O15 and Bi4W0.5Ti0.5O8 Cl.Material and experimental design were applied to upon materials to promote the catalytic efficiency.Catalytic acitivity of ferroelectric polarization enhanced photogenerated charges separation,migration of piezopotential-driven free carrier and piezopotential enhanced photogenerated charges separation are all stuied.Firstly,the ternary layered Bi-based titanate Bi4Ti3O12 with a perovskite structure was prepared by hydrothermal method,and its photocatalytic and piezocatalytic properties were explored.The morphology of Bi4Ti3O12 was modulated by introducing mineralizer strategy,and its photocatalytic degradation activity on various types of pollutants was studied.The photoelectrochemistry,production of active oxygen species and the degradation mechanism were discussed.Meanwhile,the piezocatalytic degradation activity of Bi4Ti3O12 on a variety of pollutants and the related process parameters were explored,reaction path of piezocatalysis was analyzed through ROS quantitative experiments in piezocatalysis induced by ultrasound.Secondly,the quaternary perovskite-type layered Bi-based titanate Sr Bi4Ti4O15 was prepared by hydrothermal method,and its performance in photocatalytic reduction of CO2 was explored.Through ferroelectric performance testing,piezoelectric response force microscopy and charge recombination characterization,and supplemented by density functional theory calculations,the article proved that the excellent CO2 photoreduction activity of Sr Bi4Ti4O15 mainly attribute to its spontaneous polarization along the [100] direction,which bulk charges can be effectively separated.The use of annealing treatment to modulate the internal polarization has achieved the improvement of photocatalytic performance.Thirdly,we synthesized the pentabasic perovskite-type Sillen–Aurivillius structured Bibased titanate: Bi4W0.5Ti0.5O8 Cl,and studied its photoresponse and pieozoresponse performance.Piezo-photocatalysis of Bi4W0.5Ti0.5O8 Cl was set based on above experimental results of charge migration behavior.Compared with single-source catalysis,the production of active species under piezo-photocatalytic is greatly improved.Electrochemical characterization and piezoresponse force microscopy shows that photogenerated charges are efficiently separated under the action of ultrasonic-induced piezo-potential.Thereby suppressed the charge recombination and leads to dozens of times increasing in catalytic rate.