Investigations Of Photocatalytic Degradation Properties Of The Three-component System In₂S₃/Ag/TiO₂ Nanotube Arrays

A new kind of three-component nanomaterials In₂S₃/Ag/TiO₂ NTs was first synthesized by physical and chemical method in this study. The three-component photocatalyst was applied to the photodegradation of organic compounds, which has great significance for purifying water environment and saving energy.Small rectangle ribbons?4×1cm²? of titanium foils were anodized 2h at a voltage of 15 V to prepare orderly TiO₂ nanotube arrays. The modification of Ag and In₂S₃ nanoparticles on the surface of TiO₂ NTs were separately made by Cyclic Voltammetry and Successive Ionic Layer Adsorption and Reaction?SILAR?. The photocatalytic reaction system was constituted by a 500 W xenon lamp as the light resource and 2,4-dichlorophenoxyacetic acid?2,4-D? and 2,4-dinitrophenol as the model compounds in the process of photodegradation. The optimum combination condition was determined by the photocatalytic removal efficiency of 2,4-D by different type of the three-component catalysts with different loading amount of Ag and In₂S₃:7c In₂S₃-5c Ag/TiO₂ NTs and 7c Ag-7c In₂S₃/TiO₂ NTs can achieve 100% removal of2,4-D in 140 min and 100 min separately.In this study, the morphology, elements and crystal structure were characterized by scanning electron microscope?SEM? and X-ray diffractometer?XRD? etc. The results show that Ag and In₂S₃ nanoparticles effectively and uniformly deposited on the surface of TiO₂ NTs without clogging. TiO₂ became anatase after the high temperature treatment. The results of photocurrent response?PR?, photoluminescence spectra?PL? and UV-vis diffuse reflection spectra?DRS? indicate the light absorption capacity was enhanced and the photo-generated electrons and holes' combination rate was lowered after the modification of Ag and In₂S₃ nanoparticles on the surface of TiO₂ NTs.The photocatalytic degradation experimental results of 2,4-D and DNP show that In₂S₃/Ag/TiO₂ NTs have a superior photocatalytic degradation ability, better than single?TiO₂NTs? and two components?Ag/TiO₂ or In₂S₃/TiO₂? catalytic system. Set up a series of 2,4-D solution in different initial concentration to explore the dynamic model during the photocatalytic degradation process. In a certain concentration range,the photodegradation process of this three-component photocatalyst is according with the first order kinetics. When the initial concentration of 2,4-D is 5mg/L, the photodegradation rate is fastest. And when the initial concentration of 2,4-D is20mg/L, the photodegradation rate is slowest. We have investigated the influence of external factors such as initial solution p H and air flow on the efficiency of photocatalytic degradation of organic compounds. When the p H is 4.23 and aeration rate is 30 m L/min, the photodegradation effect of 15mg/L 2,4-D is good: It can be removed by 7c Ag-7c In₂S₃/TiO₂ NTs in 60 min. When the p H is 4.86 and paeration rate is 30 m L/min, the photodegradation effect of 12.5mg/L DNP is good: It can be removed by 7c Ag-7c In₂S₃/TiO₂ NTs in 80 min.