Construction And Photocatalytic Performance Research Of Silver Iodide Based Heterojunction

Semiconductor photocatalytic technology has good application prospects in alleviating environmental problems and energy crisis by using clean and pollution-free solar energy as energy source.The core of photocatalytic technology is semiconductor material.Silver halide is a kind of semiconductor material with proper energy band position and favorable photo absorption performance.This dissertation selects the photosensitive material of silver iodide for modification and design a heterostructure composite photocatalyst based on silver iodide with high economic value,simple preparation process and excellent photocatalytic performance.This will provide a new direction for the construction of efficient photocatalytic materials.In this context,heterojunction photocatalysts of n-n-type BiPO4/AgI and Z-type B-g-C3N4/AgI were prepared.In order to study the microscopic morphology,chemical element composition,bonding state,the optical and electrical properties of the synthesized sample,characterizations of X-ray diffraction(XRD),scanning electron microscope(SEM)and ultraviolet visible diffuse reflectance spectroscopy(UV-Vis DRS)etc.,were carried out.Tetracycline hydrochloride(TC)was selected as a simulated antibiotic wastewater and methylene blue(MB)and Rhodamine B(RhB)were used as simulated dye wastewater to evaluate the photocatalytic performance of the material.The degradation mechanism was systematically studied based on the experimental and characterization results.The details were summarized as follows:1.Hexagonal-shaped BiPO4 was prepared by solvothermal method.Then a series of BiPO4/AgI heterojunction photocatalysts were synthesized by in-situ precipitation method.Various characterizations showed that the composite material was successfully synthesized,and the special morphology of BiPO4 could provide more AgI-loaded sites,enhance the interface synergy of the material,and further broad the response range of BiPO4 to visible light.Next,studies on the degradation of TC and MB under visible light conditions demonstrated that the BiP04/AgI composite had higher photocatalytic activity.Among them,AB-24 exhibited the best degradation efficiency.Finally,the possible n-n-type heterojunction photocatalytic mechanism was investigated in detail by analyzing the results of characterization and capturing experimental.2.A series of B-g-C3N4/AgI heterojunction composites were synthesized by in-situ precipitation method using the flaky B-g-C3N4 which was prepared by calcination method as the precursor at room temperature.The characterization results proved that boron was successfully doped into g-C3N4,and the modification of ion-doped narrowed its band gap.At the same time,the sheet-shaped B-g-C3N4 with porous structure provided AgI more attachment sites and the photocatalytic activity was enhanced effectively.Investigations on the degradation of TC and RhB under visible light conditions exhibited that B-g-C3N4/AgI had better photocatalytic activity,and the degradation efficiency of TC and RhB by 5:1BCNAg reached 88%and 99%,respectively.Finally,combing the results of characterization analysis,simulated degradation kinetics and capture experiment,the internal photocatalytic mechanism of improving photocatalytic activity was deeply explored and proposed the Z-type B-g-C3N4/AgI heterojunction.