| The issues of Environmental pollution control and improvement have been in the eye of the storm.Different from other control methods for pollution,semiconductor photocatalyst can degradate pollutants that can not be treated by conventional methods,such as inert organic matter,Cr(VI)and other heavy metals in water.And it has a mild reaction condition that it can directly use sunlight as a source and it has some other unique advantages.China’s molybdenum resources production ranks second in the world,the new molybdate semiconductor catalyst have a wide range of applications in the optical fiber,humidity sensors,luminescent materials,magnetic materials,catalytic materials,antibacterial materials,etc.In recent years,Due to the specific structure and physical and chemical properties,molybdate is often selected as the basis for new composite photocatalytic materials.But research which through the adding of co-catalyst,with the organic poly-modified method which can promote the space charge separate and transfer is less.In this paper,the combination of soft chemical method and solvent method was used to synthesize molybdate complexes with different morphologies.The photocatalytic activity of silver molybdate/lead molybdate were studied by the degradation of pollutants and the activity of reducing Cr(VI).The main contents of this paper are as following:1)Silver molybdate was selected as the research object.Ag/Ag2MoO4 composites with visible photocatalytic activity based on SPR effect were prepared by adding sodium dodecyl sulphate and adjusting the conditions of hydrothermal reaction(water and heat time,system pH,surfactant addition)by using soft chemical method.XRD,DRS,XPS and SEM techniques were used to characterize the materials.And the effects of reaction conditions on the crystal phase and microstructure of the product and its ability to catalyze the degradation of RhB in visible light were investigated by XRD,DRS,XPS and SEM techniques.The photocatalytic mechanism of Ag/Ag2MoO4 composites under visible light was explored by capture agent experiment and photocurrent.The pH and theamount of surfactant both have a great effect on the morphology of the composites.The Ag/Ag2MoO4 composites with octahedral have a strong absorption in the visible region and a high degradation activity of Rhodamine B.The results showed that the active species which have a decisive effect were photogenerated hole,and the ·OH also played a certain role.2)Using a variety of methods to control the synthesis of a variety of different morphology control lead molybdate substrate.The PbMoO4 crystals were synthesized by controling the mount of sodium oleate which is the surfactant and Dilute nitric acid in synthesis of octahedral micrometer scale PbMoO4 material.The conjugated polymers,benzothiadiazole acted as a modified material,improved the performance of different grades of lead molybdate significantly.And the modification of the micrometer scale is inferior to that of nanometer scale lead molybdate,which is due to the tightness between the surface and the composite,and the coating states determined the adsorption of Cr(VI)and electron transportion.The physical and chemical properties of the obtained materials were characterized by SEM,TEM and BET.XPS,XRD,Raman,FTIR,HRTEM,which proved the combination successful.The material activity and mechanism were proven by DRS,PL,photocurrent.At the wavelength of 420 nm,the amount of catalyst was 1g/L,BBT-PMO(Nano)composites reacted for 20 min,99.9% Cr(VI)was reduced,and its kinetic constants are nearly 30 times higher than BBT and nearly 50 times higher than PMO(Nano).Under the same conditions,the kinetic constants of16.7% BBT-PMO(Nano)were nearly 10 times higher compared to 13.3% BBT-PMO.It is judged that electrons are the main active species of the reduction reaction by the introduction of nitrogen,and the superoxide group also plays a certain role.It is concluded by DRS and PL that under visible light,the polymer generates carriers,which can promote electron transport by combining with lead molybdate,which improved the catalytic activity of the material.3)P35-TT-PMO and P34-ET-PMO composites were synthesized by in-situ generation method,and XRD,XPS PL were used to Characterize two kinds of polymers,linear and mesh.At λ> 450 nm,the photocatalytic reduction of Cr(VI)activity was investigated.The optimum compound ratios of the polymers in the two composites were both 16.7%,and the binding of PMO to the polymer was confirmed by TEM,Raman et al.Compared with the two pure polymers,the photocatalytic reduction of Cr(VI)properties of composites has been greatly improved.The enhancement of light absorption,the increase of the surface and the effective separation of the carriers are the key factors to improve the photocatalytic activity of the composites.The results show that the separation efficiency of 16.7% P33-TT-PMO is higher than that of 16.7% P34-ET-PMO. |
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